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DOI： 10.1007/s10971-022-05883-0

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DOI： 10.1007/s10971-022-05758-4

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DOI： 10.1063/5.0087551

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DOI： 10.1116/6.0001717

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Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media {LLC}  

DOI： 10.1007/s10971-021-05664-1

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Publishing type：Research paper (scientific journal)   Publisher：{AIP} Publishing  

DOI： 10.1063/5.0051007

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Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media {LLC}  

DOI： 10.1007/s10971-020-05323-x

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Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media {LLC}  

DOI： 10.1007/s10971-019-05212-y

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Publishing type：Research paper (scientific journal)  

DOI： 10.1039/D0RA01047B

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Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s10854-020-04433-0

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Other Link： http://link.springer.com/article/10.1007/s10854-020-04433-0/fulltext.html

Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media {LLC}  

DOI： 10.1007/s10971-019-05112-1

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society ({ACS})  

DOI： 10.1021/acs.langmuir.9b02455

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Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media {LLC}  

DOI： 10.1007/s10971-019-05088-y

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Publishing type：Research paper (scientific journal)   Publisher：Elsevier {BV}  

DOI： 10.1016/j.tsf.2018.10.050

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DOI： 10.2109/JCERSJ2.19044

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DOI： 10.1016/J.TSF.2018.10.050

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer New York LLC  

Abstract: When titanium alkoxides are hydrolyzed for preparing coating solutions for titania thin film deposition, chelating and peptizing agents such as acetylacetone and hydrochloric acid, respectively, are employed in order to suppress the formation of precipitates and obtain homogeneous sols. The present work demonstrates that precipitation can be avoided when 2-methoxyethanol is used as solvent for hydrolyzing titanium isopropoxide even without using chelating or peptizing agents. A sol obtained from a simple solution of molar compositions, Ti(OC3H7 i)4:H2O:CH3OC2H4OH = 1:1:25, was demonstrated to be stable in viscosity at least for &gt
1 month. The stability and long pot life of the sol were evidenced in the identical characters including thickness, crystallite size and refractive index and the similar microstructure of the films prepared from the sols aged for 1 and 30 days at room temperature. The formation of homogeneous sol and its long-period stability were thought to result from chelation of the titanium atoms by 2-methoxyethanol molecules. [Figure not available: see fulltext.]

DOI： 10.1007/s10971-018-4715-x

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Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry ({RSC})  

DOI： 10.1039/C8NR00793D

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Publishing type：Research paper (scientific journal)  

DOI： 10.2109/JCERSJ2.18112

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

We suggest a novel wet coating process for preparing indium tin oxide (ITO) films from simple solutions containing only metal salts and water via evaporation-driven film deposition during low-speed dip coating. Homogeneous ITO precursor films were deposited on silica glass substrates from the aqueous solutions containing In(NO3)(3)center dot 3H(2)O and SnCl4 center dot 3H(2)O by dip coating at substrate withdrawal speeds of 0.20-0.50 cm min(-1) and then crystallized by the heat treatment at 500-800 degrees C for 10-60 min under N-2 gas flow of 0.5 L min(-1). The ITO films heated at 600 degrees C for 30 min had a high optical transparency in the visible range and a good electrical conductivity. Multiple-coating ITO films obtained with five-times dip coating exhibited the lowest sheet (rho(s)) and volume (rho(v)) resistivities respectively of 188 Omega sq(-1) and 4.23 X 10(-3) Omega cm, respectively.

DOI： 10.1021/acs.langmuir.7b00823

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Anatase thin films were prepared on various plastic substrates by our recently developed sol gel transfer technique. Polycarbonate (PC), poly(methyl methacrylate) (PMMA), polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polyether ether ketone (PEEK), and polyvinylidene chloride (PVDC) were employed as plastic substrates. A Si(100) substrate was first coated with a polyimide (PI)/polyvinylpyrroli-done (PVP) mixture layer, and an alkoxide-derived titania gel film was deposited on it by spin-coating. The resulting titania gel film was heated to 600 degrees C, during which the PI/PVP layer decomposed and the gel film was converted into a 60 nm thick anatase film. The anatase film was then transferred from the Si(100) substrate to the plastic substrate. This was achieved by heating the plastic/anatase/Si(100) stack in a near-infrared image furnace to 120-350 degrees C, depending on the type of plastic substrate, under unidirectional pressure. The anatase film cracked during transfer to PE, PP, PEEK, and PVDC substrates but did not crack during transfer to PC, PMMA, and PET substrates. The fraction of the total film area that was successfully transferred was assessed with the aid of image analysis. This fraction tended to be large for plastics with C=O and C-O groups and small for those without these groups. The film/substrate adhesion assessed by cross-cut tape tests also tended to be high for plastics with C=O and C-O groups and low for those without these groups. The adhesion to plastics without C=O or C-O groups could be enhanced and their transfer area fraction increased by oxidizing the native plastic surface by ultraviolet ozone treatment prior to transfer.

DOI： 10.1021/acs.langmuir.6b04142

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

We prepared cupric oxide (CuO) photocathode films by dip coating from Cu(NO3)(2) aqueous solutions containing poly(vinylpyrrolidone) (PVP). The addition of PVP modified the wettability of FTO glass substrates by the aqueous coating solutions, resulting in the formation of CuO coating layers on the substrates. The thermal decomposition of PVP by provided nanoscale pores in the resultant CuO films, and the porosity increased with increasing PVP content. The porous structure thus obtained led to an efficient photocathodic reaction under UV and visible light illumination (wavelength: 300-800 nm). Highly porous CuO films prepared at [PVP] = 0.25 M exhibited the maximum incident photon-to-current efficiency (IPCE) values of 8.7% and 3.9% at 300 and 500 nm, respectively.

DOI： 10.1039/c6ra26590a

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Publishing type：Research paper (scientific journal)  

DOI： 10.1007/S10971-016-4291-X

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier B.V.  

Si(100) substrates were coated with a polyimide (PI)–polyvinylpyrrolidone (PVP) mixture film, and an alkoxide-derived TiO2 gel film was deposited on it by spin-coating. The gel films were fired under various conditions with final annealing at 600–1000 °C. The PI–PVP layer was completely decomposed at such high temperatures while the TiO2 films survived on Si(100) substrates without any damages. When the final annealing temperature was raised, the crystalline phase changed from anatase to rutile, and the crystallite size and the refractive index of the films tended to increase. The TiO2 films thus fired on Si(100) substrates were transferred to polycarbonate (PC) substrates by melting the surface of the plastic substrate either in a near-infrared image furnace or on a hot plate under a load. Cycles of deposition and firing were found to be effective in achieving successful transfer even for the films finally annealed at 1000 °C. X-ray photoelectron spectroscopic analyses on the film/Si(100) interface suggested that the residual carbon or carbides at the interface could be a possible factor, but not a necessary and decisive factor that allows the film transfer.

DOI： 10.1016/j.jascer.2016.06.003

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

We prepared tungsten trioxide (WO3) photo electrode films from organic-additive-free aqueous solutions by a low-speed dip-coating technique. The evaporation-driven deposition of the solutes occurred at the meniscus during low speed dip coating, resulting in the formation of coating layer on the substrate. Homogeneous WO3 precursor films were obtained from (NH4)(10)W12O41 center dot 5H(2)O aqueous solutions and found to be crystallized to monoclinic WO3 films by the heat treatment at 400-700 degrees C. All the films showed a photoanodic response irrespective of the heat treatment temperature, where a good photoelectrochemical stability was observed for those heated over 500 degrees C. The highest photoanodic performance was observed for the WO3 film heated at 700 degrees C, where the IPCE (incident photon-to-current efficiency) was 36.2% and 4.6% at 300 and 400 nm, respectively.

DOI： 10.1021/acs.langmuir.6b00377

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Language：English   Publisher：IOP PUBLISHING LTD  

DOI： 10.7567/APEX.9.039201

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Evaporation-driven surface tension gradient in the liquid layer often causes the convective flow, i.e., Benard-Marangoni convection, resulting in the formation of cell-like patterns on the surface. Here, we prepared sol-gel-derived titania films from Ti(OC3H7i)(4) solutions by dip coating and discussed the effect of the addition of co-solvents with a high surface tension and low volatility on the spontaneous pattern formation induced by Benard-Marangoni convection. Propylene glycol (PG, with a surface tension of 38.6 mN m(-1)) and dipropylene glycol (DPG, with a surface tension of 33.9 mN m(-1)) were added to the coating solutions containing 2-propanol (2-Pr, with a surface tension of 22.9 mN m(-1)) for controlling the evaporation-driven surface tension gradient in the coating layer on a substrate. During dip coating at a substrate withdrawal speed of 50 cm min(-1) in a thermostatic oven at 60 degrees C, linearly arranged cell-like patterns on a micrometer scale were spontaneously formed on the titania gel films, irrespective of the composition of coating solutions. Such surface patterns remained even after the heat treatment at 200 and 600 degrees C, where the densification and crystallization of the titania films progressed. The width and height of the cell-like patterns increased with increasing PG and DPG contents in the coating solutions, where the addition of PG resulted in the formation of cells with a larger height than DPG.

DOI： 10.1021/acs.langmuir.5b02929

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Organically modified polyoxotitanates were prepared by hydrolyzing titanium tetra-n-butoxide in the presence of benzoylacetone (BzAc) in solution at Ti(OC4H9)(4) : BzAc : H2O : CH3COCH3 mole ratios of 1 : (1 or 2) : (1 or 10) : 20. The solutions were concentrated at 80 degrees C and dried at 140 degrees C in N-2 flow, producing transparent and yellow materials of BzAc-modified polyoxotitanate. The materials had refractive indices of similar to 1.7 and exhibited thermoplastic softening at temperatures below 70 degrees C. Low contents of BzAc and high contents of H2O in solution led to higher softening temperatures of the materials, indicating the tunability of the softening temperature. Gel permeation chromatographic analyses showed that the higher softening temperatures originated mainly from polymerized species of higher molecular weights that were generated by hydrolysis and condensation reactions promoted by the low BzAc and high H2O contents in solution. (C) 2015 Wiley Periodicals, Inc.

DOI： 10.1002/APP.42653

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Nanostructured SnO particles were produced by aging Sn6O4(OH)(4) in aqueous solutions containing HCl and gelatin at 60 degrees C, where the morphologies of the SnO products depended on the pH value and the gelatin concentration of the solutions. Flower-like and spherical architectures consisting of radially-branched platy units were obtained by the addition of gelatin, where the branching of SnO crystals was promoted with decreasing pH value and with increasing gelatin contents. The branched structures thus obtained could be formed via diffusion-controlled growth of SnO crystals in viscous solutions.

DOI： 10.1039/c4ce01829j

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Here we propose a novel coating technique with low-speed dip-coating for preparing metal oxide thin films from organic-additive-free aqueous solutions, where the film formation on the substrate is achieved via an evaporation-driven deposition during dip-coating of extremely low substrate withdrawal speeds below 1.0 cm min(-1) in a thermostatic oven at 25-60 degrees C. Transparent, crack-free SnO2 and TiO2 precursor films were obtained from SnCl4 and TiOSO4 aqueous solutions, respectively, by low-speed dip-coating. The precursor films thus obtained were crystallized to SnO2 and TiO2 films by the heat treatment at 700 degrees C for 10 min in air.

DOI： 10.1039/c4ra16810k

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DOI： 10.7567/APEX.8.105801

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

Formation of bismuth nano-particles by polyol process have been studied in terms of the effect of additives on its size and shape. Bismuth trichloride solved in ethylene glycol was reduced at high temperature with the existence of poly(vinylpyrrolidone) (PVP) and ferric chloride. Spherical particles were mostly formed with the solitary addition of PVP. Sphere size was decreased from 400 to 200 nm with increasing amount of the PVP. Addition of larger weight-average molecular weight (M-w) of the PVP decreased the sphere size slightly. On the other hand, hexagonal or rectangular plate-like particles were obtained at a high number ratio over 70% by the co-addition of ferric chloride with the PVP. Plate size and the fraction of plate-like particles tended to increase slightly with the increase of amount of the PVP. The plate size also increased with increase of molecular weight of the PVP and square plate-like particles larger than 1 micrometer were obtained with the addition of the large molecular size of PVP (M-w similar to 1,300,000). Adequate amount and size of PVP tended to decrease totally the growth speed of particles and to suppress coalescence with each other, and ferric ions suppressed the growth speed toward the c-axis by alternative re-oxidization of bismuth metal. (C) 2014 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.122.917

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

Crystalline SnO particles were obtained from Sn6O4(OH)(4) by the hydrothermal treatment in aqueous solutions containing gelatin at 150 degrees C for 24 h, where the morphologies of the SnO products changed from blocks to layered disks, stacked plates and unshaped aggregates with increasing amount of gelatin in the solutions. Such morphological changes of SnO particles were thought to be attributed to the suppression of the growth of SnO crystals by the adsorbed gelatin. (C) 2014 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.jssc.2014.05.023

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier  

We prepared silica-poly(vinylpyrrolidone) (PVP) hybrid films containing a photoluminescent organic dye, rhordamine 6G (R6G), by low-speed dip-coating, where the spontaneous pattern formation was induced in the films. Stripe patterns arranged perpendicular to the substrate withdrawal direction were spontaneously formed by stick-slip motion at the meniscus during dip-coating, and the film structure (i.e., the film thickness, and the height, width and spacing of stripe patterns) was changed with increasing amounts of volatile solvent (C2H5OH) in solutions (C2H5OH/Si(OCH3)4 mole ratio (x)=20-150). As a result of the optimization of the film structure, localized photoluminescence at the stripe patterns was achieved over x=120. © 2014 Elsevier B.V.

DOI： 10.1016/j.colsurfa.2014.03.066

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Titanium tetra-n-butoxide was hydrolyzed in the presence of benzoylacetone (BzAc), and the solution obtained was concentrated and served for spin-coating or dropping on substrates, followed by successive drying at 120, 200 and 250 A degrees C. The dried products were transparent and amorphous, and the infrared absorption and Raman spectroscopic studies showed that BzAc forms chelate rings. Thermomechanical analysis showed that the 120 and 200 A degrees C-dried products showed steep, thermoplastic shrinkage at around 30 and 70-85 A degrees C, respectively, whereas the 250 A degrees C-dried product did not show thermoplasticity. Thus as the drying temperature was increased, the thermoplasticity appeared at a higher temperature and finally disappeared. These changes in thermoplasticity with drying temperature were concluded to result from the progress of condensation between titanoxane polymers and/or clusters, which was evidenced in gel permeation chromatographic analysis.

DOI： 10.1007/s10971-014-3304-x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Sol-gel-derived TiO2 films were prepared by dip-coating from Ti(OC3H7i)(4)-CH3COCH2COCH3-HNO3-H2O-C2H5OH solutions, and the effect of the H2O content in solutions on the crystallization of TiO2 films during the heat treatment at 800 degrees C was discussed. The crystalline phase, crystallite size, grain size, and refractive index of the TiO2 films depended on the H2O/Ti(OC3H7i)(4) mole ratios (x) in the coating solutions. Highly dense and crystalline rutile films were obtained at x=0.5-10, where the crystallites and grains became larger with increasing x. The further increase in x from 10 to 50 reduced the crystallite size and refractive index of the films, where anatase phase appeared at x=30-50.

DOI： 10.1111/jace.12860

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Preparation of silica thin films from perhydropolysilazane (PHPS) at room temperature has attracted much attention because it provides a new way to realize silica thin films in a variety of technologies where any high temperature processes should be avoided. Although silica gel films can also be prepared from alkoxides at room temperature by conventional sol-gel method, they are believed to have low mechanical and chemical durability. However, even such alkoxide-derived silica gel films have possibilities to become more durable via condensation reaction and densification when aged at room temperature. In Order to clarify whether or not PHPS-derived silica thin films have critical superiority on properties, the hardness and chemical durability were compared between PHPS- and alkoxide-derived silica thin films, where PHPS films were exposed to the vapor from aqueous ammonia at room temperature for PHPS-to-silica conversion. Alkoxide-derived silica gel films were found to be densified and hardened when stored in air at room temperature, which resulted in pencil hardness even higher than 9H on Si(100) substrates. However, the ultra-microindentation tests demonstrated that the PHPS-derived films are definitely harder than the alkoxide-derived ones. The PHPS-derived films were also found to have higher chemical durability in water and in aqueous ammonia. Such higher mechanical and chemical durability of the PHPS-derived films was ascribed to their higher density, i.e., more highly condensed states, which was evidenced in infrared absorption spectra. Hard coating performance on plastic substrates was also studied, and the PHPS-derived films were demonstrated to have much higher adhesive strength on polymethylmethacrylate substrates. The in-plane stress measurement demonstrated that the PHPS-derived films have much lower or even negligible tensile stress, which may be one of the causes for such higher adhesive strength.

DOI： 10.1021/am400845y

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Spin-on perhydropolysilazane (PHPS) thin films were converted into mechanically hard silica thin films by an exposure to the vapor from aqueous ammonia. Infrared absorption and X-ray photoelectron spectroscopic analyses were conducted to clarify the details of the PHPS-to-silica conversion and the nature of the silica thin film products. The PHPS-to-silica conversion was found to proceed rapidly between 2 and 3h of exposure via a reaction-limited process, where the refractive index and the pencil hardness greatly decreased and increased, respectively. Finally, the O/Si mole ratio close to 2 was achieved, which has never been realized in literature for PHPS-derived silica thin films. It was also found that the condensation of Si-OH groups proceeds in films immediately after PHPS hydrolysis, which is similar to the base-catalyzed hydrolysis-condensation reaction of silicon alkoxides. Although the silica thin films obtained had refractive indices similar to that of silica glass, high pencil hardness over 9H on Si(100) substrates, and O/Si mole ratios close to 2, it was concluded that they are nonidentical to silica glass, containing trace amounts of Si-OH and Si-H groups.

DOI： 10.1111/jace.12513

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A technique that realizes alternating, two kinds of ceramic ribbons on plastics is proposed. An Si(100) plate with periodic trenches coated with a polyimide (PI)-polyvinylpyrrolidone (PVP) mixture layer was used as the mother substrate. An indium-tin-oxide (ITO) thin film was deposited on the mother substrate by the sol-gel method with a firing process, followed by transferring it to a polycarbonate (PC) substrate by melting the PC surface in contact with the ITO thin film. This resulted in patterned ITO ribbons on the PC substrate where the ridges of PC were formed between the ribbons. A ZnO thin film was prepared on a flat Si(100) substrate coated with a PI-PVP mixture layer, followed by firing, and then was transferred on the PC ridges in the same manner, resulting in alternating ITO and ZnO ribbons on the PC substrate. The technique proposed here allows dense, alternating ceramic ribbons to be fabricated on plastics irrespective of the combinations of ceramics and plastics. © 2013 Springer Science+Business Media New York.

DOI： 10.1007/s10971-013-3081-y

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Publishing type：Research paper (scientific journal)  

DOI： 10.1557/JMR.2013.13

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Zn2SnO4 films were prepared by dip-coating from the solutions consisting of Zn(CH3COO)(2)center dot 2H(2)O, SnCl4 center dot 5H(2)O, H2O, CH3COCH2COCH3 and CH3OC2H4OH, and the photoanodic properties were compared to those of the ZnO and SnO2 films prepared via the same synthetic route. Here, the photoanodic properties were studied in a three-electrode cell with an aqueous buffer solution of pH = 7 as the supporting electrolyte. The Zn2SnO4, ZnO and SnO2 films exhibited photoanodic response under the UV light illumination. The Zn2SnO4 film exhibited the higher IPCE at wavelengths of 250-275 nm than the ZnO and SnO2 films, while the ZnO film showed the highest IPCE at wavelengths of 300-375 nm. The higher photoanodic currents could be attributed to the higher photoabsorbance of the Zn2SnO4 and ZnO films at wavelengths of 200-290 nm and 290-390 nm, respectively. (C) 2012 Elsevier B. V. All rights reserved.

DOI： 10.1016/j.jallcom.2012.11.196

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Nanostructured CeCO3OH particles were prepared from aqueous solutions and gels containing CeCl3 and biological polymers (gelatin and agar) by the addition of (NH4)(2)CO3 solutions. The morphologies of the CeCO3OH products depended on the kind and concentration of the biological polymers. Sheaf- and cocoon-like CeCO3OH particles of ca. 2 mu m in size consisting of fine particles of ca. 10 nm in diameter were obtained from the precursor solutions containing gelatin. On the other hand, CeCO3OH precipitates with inhomogeneous size and shape were obtained from the precursor solutions and gels containing agar. Such morphological variation of CeCO3OH particles was thought to be due to the suppression of nucleation and growth of CeCO3OH crystals by the biological polymers. The CeCO3OH particles thus obtained were converted to CeO2 particles by the heat treatment at 600 degrees C, and the morphology as well as nanostructure remained during the heat treatment.

DOI： 10.1039/c3ra43580f

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier B.V.  

Sol-gel derived TiO2 films were prepared from the solutions containing Ti(OC3H7i)4, H2O, HNO3 and C2H5OH by dip-coating, and the effects of the processing parameters (the heat-treatment temperature and time, and the H2O contents in the coating solutions) on the crystallization and densification of TiO2 films during the heat treatment in air were discussed. Anatase films were obtained by the heat treatments over 400°C, and the increase in heat-treatment temperature and time led to a decrease in film thickness and an increase in grain size, crystallite size and refractive index of the films. Moreover, the crystal growth and grain growth were promoted with increasing H2O content in the coating solutions during the heat treatments over 500°C, while the crystallization and densification were suppressed by the slow condensation of TiOH species below 400°C at larger H2O contents. © 2013 The Ceramic Society of Japan and the Korean Ceramic Society.

DOI： 10.1016/j.jascer.2013.06.001

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A versatile technique for fabricating ceramic thin films on plastics has been proposed. The technique comprises (i) the deposition of a gel film by spin- or dip-coating on a silicon substrate coated beforehand with a release layer, (ii) the firing of the gel film into a ceramic film, and (iii) its transfer onto plastics by melting or softening the plastics surface. Reflective anatase and electrically conductive indium-tin-oxide (ITO) thin films were prepared on acrylic resin and polycarbonate substrates. Patterned ITO thin films could also be fabricated on plastics by using a mother silicon substrate with periodic grooves.

DOI： 10.1021/am3019993

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Complex, sophisticated surface patterns on micrometer and nanometer scales are obtained when solvent evaporates from solutions containing nonvolatile solutes dropped on a solid substrate. Such evaporation-driven pattern formation has been utilized as a fabrication process of highly ordered patterns in thin films. Here, we suggested the spontaneous pattern formation induced by Benard-Marangoni convection triggered by solvent evaporation as a novel patterning process of sol-gel-derived organic-inorganic hybrid films. Microcraters of 1.0-1.5 mu m in height and of 100-200 mu m in width were spontaneously formed on the surface of silica-poly(vinylpyrrolidone) hybrid films prepared via temperature-controlled dip-coating process, where the surface patterns were linearly arranged parallel to the substrate withdrawal direction. Such highly ordered micropatterns were achieved by Benard-Marangoni convection activated at high temperatures and the unidirectional flow of the coating solution on the substrate during dip-coating.

DOI： 10.1021/la3020332

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We prepared ZrO2 particles from the solutions containing Zr(OC3H7n)(4). H2O, n-C3H7OH and acetylacetone (acac) via solvothermal treatment at 150 degrees C. The particle size and shape depended on the molar composition of the precursor solutions. Micron-sized spheres consisting of cubic and tetragonal ZrO2 with low crystallinity were obtained via hydrolysis of Zr(OC3H7n)(4) modified with acac, and the size of the spheres decreased from 2-10 mu m to 0.5 mu m with increasing amount of H2O and n-C3H7OH at constant n-C3H7OH/H2O mole ratios. The non-aggregated, homogeneous microspheres can be observed even by optical microscopy. The crystallinity of the ZrO2 spheres were improved by the heat treatment at 600 degrees C, and the spherical shape remained during the heat treatment. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.colsurfa.2012.03.065

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

Strain imaging of piezoelectric material enables us to observe piezo/ferroelectric properties with high resolution. We observed single-step-deposited 0.4-mu m-thick Pb(Zr0.53Ti0.47)O-3 (PZT). The PZT film had the small granular grains in size with around 40 nm, while the rosettes were around several micrometers in diameter. Observed domain structures were only determined by the rosette structures formed by nucleation of PZT. The grains were not columnar but granular, and so there are many grains in thickness direction but they were (001)-oriented. Therefore, polarization was aligned normal to the surface, and the structure to determine domain boundaries is neither grain boundaries nor crystalline axes but rosette boundaries. Relatively thick films provided stable polarization. The domain structures are flexible and well controllable by external electric fields. The positive surface charges were generated in the PZT surface by negative tip voltages. The presented images suggest that the positive surface charges coupled with spontaneous polarizations were rich at the circumferences of the rosettes. The positive surface charges generated negative charges on the tip, and the negative charges were deposited on the sample surface from the scanned tip. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3693042]

DOI： 10.1063/1.3693042

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Optically transparent, ca. 200-800 nm thick TiO2-hydroxypropylcellulose (HPC) hybrid thin films were prepared from Ti(OC3H7i)(4)-HPC-HCl-H2O-(C3H7OH)-O-i solutions by the sol-gel method, where the as-deposited films were dried at 120 degrees C. The effects of the amount of HPC, H2O and HCl in the starting solutions on the refractive index and uncracking critical thickness of the films were studied, where the effects on the critical thickness was discussed on the basis of in situ stress measurements during heating. The increase in HPC content increased the critical thickness and lowered the refractive index. The increase in HCl content resulted in a decrease in critical thickness and an increase in refractive index. Larger H2O contents gave rise to a maximum in critical thickness while the refractive index was unaffected. Such variation in critical thickness with varying solution compositions was demonstrated to result from the differences in in-plane stress generated during heating. By optimizing the processing parameters an 810 nm thick TiO2-HPC hybrid film of a refractive index of 1.84 was obtained.

DOI： 10.1007/s10971-011-2649-7

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

We prepared a new class of organic inorganic hybrid materials with high refractive indices and thermoplasticity. Titanium and zirconium alkoxides were hydrolyzed in the presence of beta-diketones of high melting and boiling points, followed by concentration and heating over 100 degrees C. Transparent, glass-like solid materials were obtained, exhibiting softening or melting behavior on heating in spite of the absence of organic polymers. The refractive indices of the thermoplastic hybrid materials were as high as 1.7.

DOI： 10.1246/cl.2012.319

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An aqueous dip-coating route without using volatile alcohols for preparing dense and porous silica thin films is presented. The films were prepared by dip-coating on Si(100) and silica glass substrates using aqueous suspension of 8-11 nm colloidal silica where no alcohols were added. The addition of polyvinylpyrrolidone (PVP) in the suspension greatly improved the wettability, allowing homogeneous films to be formed on the substrates while the substrates showed poor wettability without PVP. When the as-deposited films were fired at 500-1,000 A degrees C, optically transparent porous films with smooth surface were obtained. The porous films had homogeneous distribution and packing of silica nanoparticles, refractive indices of 1.24-1.33, and pencil hardness lower than 6B. The porous films underwent significant densification by viscous sintering when fired at temperatures over 1,000 A degrees C. The viscous sintering was accompanied by the progress of condensation reaction and by the structural relaxation of siloxane network, which was revealed in the infrared absorption spectra. The resulting dense films had optical transparency, smooth surface, pencil hardness over 9H and refractive indices close to that of silica glass.

DOI： 10.1007/s10971-011-2638-x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We prepared TiO2-ZrO2 binary oxide particles with various Ti/(Zr+Ti) mole ratios (x) from the solutions containing Ti(OC3H7i)(4), Zr(OC3H7n)(4) and acetylacetone (acac). The spherical particles of 1-5 mu m in diameter were obtained via solvothermal treatment at 150 degrees C. The spheres were anatase at x=1 and amorphous at x=0-0.8. The spheres were thought to be formed through the moderate hydrolysis and nucleation provided by the chelation of the alkoxides by acac. Crystalline TiO2-ZrO2 particles were obtained by the heat treatment of the as-precipitated spheres, and the crystalline phase changed with the Ti/(Zr+Ti) mole ratios. Pure ZrO2 and TiO2, ZrO2 doped with Ti4+, TiO2 doped with Zr4+ and ZrTiO4 phases were produced, and the spherical shape remained after the heat treatment at 500-750 degrees C. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jcrysgro.2011.11.035

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

The in-plane residual stress in thin films greatly affects their properties and functionality as well as the substrate bending, and hence is an important factor to be controlled. In order to obtain general knowledge on the development of residual stress in sol-gel-derived oxide thin films, the in-plane residual stress was measured for yttria stabilized zirconia gel films on Si(100) wafers as a function of firing temperature by measuring the substrate curvature. The films showed a rather complex variation in residual stress, and the mechanism of the residual stress evolution was discussed, referencing the intrinsic stress and the x-ray diffraction data. At low annealing temperatures of 100-200 degrees C, the residual tensile stress decreased and became compressive partially due to the structural relaxation occurring during cooling. When the firing temperature was increased over 200 degrees C, the residual stress turned tensile, and increased with increasing annealing temperature, which was attributed to the increase in intrinsic stress due to film densification as well as to the reduced structural relaxation due to the progress of densification. The residual tensile stress slightly decreased at firing temperatures of 500-600 degrees C, which was attributed to the reduction in intrinsic stress due to thermally activated atomic diffusion as well as to emergence of thermal stress. At firing temperature over 600 degrees C, the residual tensile stress increased again, which was attributed to the increase in thermal stress generated during cooling due to the increased Young's modulus of the film. Although appearing to be complicated, the whole variation of residual stress with firing temperature could be understood in terms of film densification, structural relaxation, atomic diffusion, progress of crystallization and thermal strain. The illustration presented in the work may provide a clear insight on how the residual stress could be developed in a variety of functional sol-gel-derived, crystalline oxide thin films. (C) 2012 American Institute of Physics. [doi: 10.1063/1.3673330]

DOI： 10.1063/1.3673330

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Cell-like patterns were spontaneously formed on the silica gels prepared by dropping acid-catalyzed tetramethyl orthosilicate (Si(OCH3)(4)) solutions containing poly(vinylpyrrolidone) (PVP) on a stationary substrate. The height of the cell-like patterns increased with increasing the contents of PVP in the precursor solutions and the substrate temperature. On the other hand, the width of the patterns decreased with increasing the substrate temperature, while did not change with the addition of PVP. Such pattern formation was caused by the Benard - Marangoni convections occurring in the precursor solutions during the solvent evaporation. The cell-like patterns on the silica gels disappeared during the aging of the gels in the solvent vapor.

DOI： 10.1021/jp2094774

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

A new general route for large area, submicron thick ceramic thin films (crystalline metal oxide thin films) on plastic substrates is presented, where the crystallization of films is guaranteed by a firing process. Gel films are deposited on silicon substrates with a release layer and fired to be ceramic films, followed by transferring onto plastic substrates using adhesives. The ceramic films thus fabricated on plastics exhibit a certain degree of flexibility, implying the possibility of the technique to be applied to high-throughput roll-to-roll processes. Using this technique, we successfully realized transparent anatase thin films that provide high optical reflectance and transparent indium tin oxide thin films that exhibit electrical conductivity on polycarbonate and acrylic resin substrates, respectively. Crystallographically oriented zinc oxide films and patterned zinc oxide films are also demonstrated to be realized on acrylic resin substrates. (C) 2012 American Institute of Physics. [doi: 10.1063/1.3676281]

DOI： 10.1063/1.3676281

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

We prepared silica-poly(vinylpyrrolidone) (PVP) hybrid films via a temperature-controlled dip-coating process and investigated the influence of the coating temperature (i.e., the temperature of substrates, solutions and atmosphere) on the spontaneous pattern formation based on the "coffee-ring effect". Micron-scale stripe patterns were spontaneously formed on the surface of the films at high coating temperatures over 40 degrees C during dip-coating. The stripe patterns were arranged perpendicular to the withdrawal direction, and the height and width of the patterns increased with increasing coating temperature. Such spontaneous pattern formation is attributed to the evaporation-driven capillary flow of coating solutions at the meniscus, and the stripe patterns with larger heights and widths are thought to be achieved by the capillary flow activated at higher coating temperatures.

DOI： 10.1039/c2sm26328a

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

We prepared crystalline SnO2 particles from aqueous solutions of SnCl4 containing poly(acrylic acid) (PAA) by hydrothermal treatment at 150 degrees C. The morphology of the SnO2 particles depended on the concentration of PAA and the pH value of the precursor solutions. The flower-like SnO2 particles of ca. 100 nm in diameter consisting of needle-like units ca. 50 nm in size were obtained from the solution of [SnCl4 center dot 5H(2)O] = 0.1 M and [PAA] = 0.02 M containing the acidic solvents of pH 0.35 via the hydrothermal treatment. The needle-like units were found to consist of nanorods of ca. 50 nm in length and ca. 5 nm in width. The flower-like SnO2 particles were thought to be formed through the moderate nucleation and growth rates that were provided by the relatively high solubility of the Sn4+ species under the acidic conditions and the their coordination by PAA.

DOI： 10.1039/c2ra01037b

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Linear patterns were spontaneously formed on the silica and titania dip-coating films prepared from tetramethyl orthosilicate (Si(OCH3)(4)) and titanium tetraisopropoxide (Ti(OC3H7i)(4)) solutions, respectively. In both films, the pattern formation occurred at extremely low substrate withdrawal speeds below 1.0 cm min(-1), where the film thickness increased with decreasing substrate withdrawal speed for dip-coating. The linear patterns on micrometre scale were arranged perpendicular to the substrate withdrawal direction. The values of R-Z (10 point height of irregularities) and S (mean spacing of local peaks) of the patterns increased with decreasing substrate withdrawal speed.

DOI： 10.1039/c1ra00770j

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

Silica gel films were prepared on Si(100) substrates from Si(OC2H5)(4)- and Si(OCH3)(4)-derived sols by dip-coating, and the gel films were heat-treated at 100-700 degrees C. The durability of the films against water was evaluated by measuring the thickness before and after soaking them in 80 degrees C water for 24 h. The durability increased with increasing heat-treatment temperature principally due to the progress of film densification. Higher amounts of water for hydrolyzing Si(OC2H5)(4) were greatly effective in achieving higher durability at lower heat-treatment temperatures. Longer sol aging was also effective in improving the durability of the Si(OC2H5)(4)-derived films. Si(OCH3)(4)-derived films exhibited much higher durability than Si(OC2H5)(4)-derived ones. All of these factors, i.e. the larger amounts of water for hydrolysis, the longer sol aging time and the employment of Si(OCH3)(4), may provide more dense film structure and more chance to undergo condensation during gel film heat-treatment, leading to the higher durability at lower heat-treatment temperatures. (C)2011 The Ceramic Society of Japan. All rights reserved.

DOI： 10.2109/jcersj2.119.434

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Fe2O3-SnO2 coating films of various Sn/(Fe + Sn) mole ratios, r(sn), were prepared by dip-coating on Nesa silica glass substrates from the solutions consisting of Fe(NO3)(3) center dot 9H(2)O, SnCl4 center dot 5H(2)O, H2O, CH3COCH2COCH3, and CH3OC2H4OH. The photoanodic properties were studied in a three-electrode cell with an aqueous buffer solution of pH = 7 as the supporting electrolyte. The Fe2O3-SnO2 films of r(sn) = 0-0.25 comprised hematite phase and exhibited photoresponse under the UV and visible light. The photoanodic response of the alpha-Fe2O3 film was enhanced by doping with Sn4+; the film of r(sn) = 0.1 exhibited the maximum IPCE (incident photon-to-current efficiency) of 26.9% and 8.6% at the wavelengths of 350 and 425 nm, respectively, which were higher than those of the Fe2O3-TiO2 film of Ti/(Fe + Ti) = 0.1 prepared by similar process. IPCE decreased with increasing r(sn) from 0.1 to 0.25. The films of r(sn) >= 0.5 comprised rutile phase without hematite phase, showing very low IPCE.

DOI： 10.1021/jp112279k

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We prepared crystalline SnO2 particles from aqueous solutions of SnCl4 with and without citric acid via hydrothermal treatment. The crystallinity, the crystallite size and shape, and the morphology of the secondary particles depend on the concentration of citric acid, the pH value of the solvents and the hydrothermal treatment temperature. Spherical SnO2 particles of 1-3 mu m in diameter consisting of nanocrystallites below 10 nm in size were obtained via hydrothermal treatment at 150 degrees C from a solution with the citric acid/SnCl4 mole ratio of 0.5 in acidic solvents of pH 3.0-5.5. The SnO2 spheres were thought to be formed through the moderate nucleation rate provided by the relatively high solubility of Sn4+ species and coordination by citric acid. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jcrysgro.2011.02.002

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Polymethylmethacrylate (PMMA)-perhydropolysilazane (PHPS) hybrid thin films doped with spiropyran were prepared by spin-coating, which were then converted into 0.26-1.7 mu m thick, spiropyran-doped PMMA-silica hybrid films by exposure treatment over aqueous ammonia. The spiropyran/(spiropyran + PHPS + PMMA) mass ratio was fixed at a high value of 0.2 so that the films exhibit visual photochromic changes in color, while the PMMA/(PMMA + PHPS) mass ratio, r, was varied. The spiropyran molecules in the as prepared films were in merocyanine (MC) and Spiro (SP) forms, with and without an optical absorption at 500 nm, at low (r <= 0.2) and high (r >= 0.4) PMMA contents, respectively. When PMMA content r was increased from 0 to 0.2, the degree of the MC-to-SP conversion on vis light illumination was enhanced, while at higher r's the spiropyran molecules underwent photodegradation. When the silica film (r=0) was soaked in xylene under vis light, the spiropyran molecules were almost totally leached out, while not on soaking in the dark. On the other hand, no leaching occurred for the film of r=0.2 either in the presence or absence of vis light. These suggest that the introduction of PMMA is effective in improving the chemical durability of the films, while the silica film (r=0) is an interesting material with a photoresponsive controlled-release ability. The pencil hardness of the films decreased with increasing PMMA content, but remained over 9H at r <= 0.4. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tsf.2010.09.034

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

The effect of third-additive oxides on absorption edge energy was studied in binary bismuth phosphate glass The edge energy was shifted toward lower energies by the substitution of third-additive oxides for P(2)O(5) The substitutions of glass-network-forming (NWF) oxides and glass-network-modifying (NWM) oxides resulted in distinct linear relationships between the edge energy and Duffy's ideal basicity The energy shift against the calculated basicity was larger for the substitution of NWF oxides than for that of NWM oxides Moreover, the substitution of intermediate oxides gave a similar tendency to the substitution of NWF oxides rather than to that of NWM oxides for both relationships It was deduced that electron donation is more sensitive to the substitution of NWF oxides than to that of NWM oxides On the other hand, a 238 cm(-1) Raman band, which is attributed to the Bi-O vibration mode, shifted toward higher wave numbers by the substitution of all of the oxides The 238 cm(-1) band showed a linear relationship with the ideal basicity similar to the relationship between the edge energy and the basicity Sensitivity against electron donation was consistent with both the Bi-O bond strength and the absorption edge energy (C) 2010 The Japan Society of Applied Physics

DOI： 10.1143/JJAP.49.082601

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Linear striations and cell-like patterns were spontaneously formed on the dip-coating Mania films prepared titanium tetraisopropoxide (Ti(OC3H7i)(4)) solutions. Such unique patterns on micrometer scale were arranged parallel to the substrate withdrawal direction. The values of R-z (10 point height of irregularities) and S (mean spacing of local peaks) of the patterns increased with increasing film thickness depending on the substrate withdrawal speed for dip-coating, the viscosity of the coating solutions, and the distance front the top edge of films. The shape of patterns changed from linear striations to cell-like patterns with increasing viscosity of the coating solutions. Although the heat treatment at 600 degrees C reduced the height (R-z) of stripes and cells without the change in spacing (S), the visibility of patterns was enhanced by the increase in refractive index due to the crystallization of films.

DOI： 10.1021/la1009708

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Formation of anatase spheres was achieved via hydrolysis of Ti(OC3H7i)(4) modified with acetylacetone (acac) under solvothermal conditions at 150 degrees C. The reduction in the degree of hydrolysis by the modification of Ti(OC3H7i)(4) with acac led to the formation of a spherical shape. The 1-5 mu m in diameter spherical particles consisted of anatase nanocrystals below 10 nm in size.

DOI： 10.1246/cl.2010.445

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Perhydropolysilazane (PHPS)-polymethylmethacrylate (PMMA)-spiropyran (SP) films were prepared by spin-coating using a solution of a mass ratio, PHPS:PMMA:SP:xylene = 0.8:0.2:0.25:3.6. The SP-doped PHPS-PMMA films were then exposed to the vapor from aqueous ammonia at room temperature, resulting in the formation of 1.7 mu m thick, deep-red colored SP-doped PMMA-silica hybrid films. Due to the high concentration of SP, which could be achieved by the hydrophobic nature of PHPS and xylene, the photochromic color changes were visualized in spite of the small film thickness. The films had pencil hardness higher than 9H, and no SP leaching was observed even when the films were soaked in xylene for 24 h. Thus, thin films that exhibit visual photochromism with high mechanical and chemical durability could be prepared, which can never been achieved by conventional sol-gel methods.

DOI： 10.1007/s10971-009-2147-3

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Titania gel films were prepared from a coating solution with a starting mole ratio of Ti(OC(3)H(7)(i))(4):H(2)O:HNO(3):C(2)H(5)OH=1:1:0.2:30 on Si(100) wafers by spin coating, with and without sol-gel-derived, fired silica, and titania underlayers. In situ measurement was conducted on the in-plane stress in the titania gel films during heating up to 500 degrees C at 5 degrees C/min. Basically, for all the gel films, the in-plane, tensile stress increases once with increasing temperature, and then decreases around the temperature of crystallization. The increase in stress was thought to result from the capillary pressure due to solvent evaporation and from the densification of the coatings. The reduction in stress around the temperature of crystallization was ascribed to the accelerated atomic diffusion in the coatings and to the difference in thermal expansion coefficient between the coatings and the Si wafer. However, when the stress-temperature curves were examined more in detail, differences were found in the variation in stress, depending on the underlayers. Then, the question of how the underlayers could induce the crystallization and relax the strain in the coatings was discussed.

DOI： 10.1111/j.1551-2916.2009.03159.x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MATERIALS RESEARCH SOC  

The effects of the catalysts on the evolution of in-plane stress during heating were studied for silica gel coatings prepared from alkoxide solutions. Tetramethylorthosilicate was hydrolyzed in the presence of nitric acid, acetic acid, and ammonia as catalysts. Gel films were deposited on Si(100) wafers by spin coating, and heated at a constant rate of 5 degrees C/min up to 500 degrees C. During heating, in situ measurement of the in-plane stress was conducted by measuring the radius of curvature of the substrate. In-plane, tensile stress increased up to 560 and 370 MPa in the films prepared with HNO(3) and CH(3)COOH, respectively. However, the stress was much smaller at 30-40 Mpa, which remained almost constant during heating, for the films prepared with NH(3). The much smaller stress resulted from the much lower degrees of the progress of densification during heating, which was revealed in the changes in thickness and infrared absorption spectra during heating. The low degrees of the progress of densification were caused by the colloidal nature of the gel films prepared with NH(3).

DOI： 10.1557/JMR.2009.0307

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Silica coatings doped with spiropyran (SP) were prepared using xylene solutions of perhydropolysilazane (PHPS) as the silica source, where the SP-doped PHPS coatings were prepared by spin-coating and the PHPS-to-silica conversion was achieved by exposing the coatings to the vapor from aqueous ammonia at room temperature. The films could be heavily doped with SP at SP/(SP + PHPS) mass ratio as high as 0.2. The as-deposited SP-doped PHPS films were transparent and light-yellow, which turned to red as the PHPS-to-silica conversion proceeded, where the absorbance at 500 run increased. When the films were stored in air in the dark for 73 h after the exposure treatment, the absorbance at 500 nm further increased, where the film turned from red to dark red. The SP-doped silica coatings thus obtained showed reversible photochromic reaction, where the absorbance at 500 nm decreased and increased when the films were irradiated with visible and ultraviolet light, respectively. The pencil hardness of the films was higher than 9H at a load of 1 kg, while significant amount of SP was leached out when the films were soaked in xylene.

DOI： 10.1021/jp809831c

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

The effects of the solvent on in-plane stress evolution were studied on sol-gel-derived silica gel coatings during heating. Si(OC(2)H(5))(4)-H(2)O-HNO(3)-ROH (ROH = CH(3)OH, C(2)H(5)OH, n-C(3)H(7)OH, and n-C(4)H(9)OH) solutions were prepared where the mole ratio Si(OC(2)H(5))(4):H(2)O:HNO(3)=1:8:0.01 and the volume ration Si(OC(2)H(5))(4): ROH=1:1.1. Silica gel films were deposited by spin coating on Si (100) wafers 4 in. in diameter, and heated at 5 degrees C/min up to 500 degrees C, where in situ stress measurement was conducted by measuring the substrate curvature. The stress was tensile and increased with increasing temperature. The stress was found 10 be identical below 200 degrees C between the films prepared with different alcohols while the stress above 200 degrees C Was larger in the order n-C(4)H(9)OH<n-C(3)H(7)OH approximate to C(2)H(5)OH<CH(3)OH, namely in the order of the boiling points of the larger in the order, solvents. (C) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tsf.2008.08.117

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DOI： 10.1021/JP9038094

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Xylene solutions of perhydropolysilazane (PHPS) were used as the coating solutions for preparing silica coatings at room temperature. The PHPS-to-silica conversion was achieved by exposing the spin-on coatings to the vapor from aqueous ammonia. In order to examine the significance of the mechanical properties of the PHPS-derived silica coatings, the pencil hardness was measured, which was compared with that of tetraethoxysilane (TEOS)-derived silica coatings. The pencil hardness was over 9H at a load of 1 kg, which was much higher than that of the TEOS-derived silica gel films, and was comparable to that of the TEOS-derived films heat treated at 300 degrees C. Second, poly(methyl methacrylate) (PMMA)-silica hybrid coatings were prepared from xylene solutions of PMMA and PHPS via exposure to the vapor from aqueous ammonia. Crack-free, optically transparent PMMA-silica hybrid coatings could be prepared, where PHPS-to-silica conversion was confirmed by infrared absorption spectroscopy. The refractive index was around 1.42-1.50, and the contact angle with water increased from 35 to 70 degrees with increasing PMMA content. The pencil hardness greatly increased during the PHPS-to-silica conversion, and was much higher than that of the non-heat treated TEOS-derived hybrid coatings. The durability in tetrahydrofuran (THF) was also evaluated by measuring the reduction in thickness occurring during soaking in THF. The durability decreased with increasing PMMA content, but was much higher than that of the non-heat treated TEOS-derived hybrid coatings. Both the hardness and the durability were comparable to those of the TEOS-derived coatings heated at 300 degrees C. The hybrid coatings could also be deposited on poly(ethylene terephthalate) substrates, where no cracks were observed at high PMMA contents even when the substrate was bent.

DOI： 10.1007/s10971-008-1793-1

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Single-step sol-gel deposition was attempted for realizing submicron thick, (001) oriented Pb(Zr(0.53)Ti(0.47))O(3) (PZT) thin films, using an alkoxide solution containing polyvinylpyrrolidone (PVP). A solution of molar composition, Pb(NO(3))(2):Zr(OC(3)H(7) (n))(4):Ti(OC(3)H(7) (i))(4):PVP:H(2)O:CH(3)COCH(2)COCH(3):CH(3)OC(2)H(4)OH:C(3)H(7) (n)OH = 1.1:0.53:0.47:0.5:5:0.5:22:0.98, was prepared as a coating solution. Gel films were prepared on Pt(111)/TiO(2)/SiO(2)/Si(100) substrates by spin-coating, and calcined at 350 degrees C and annealed at 650 degrees C either in an electric furnace or in a near-infrared (IR) furnace. When calcined in the near-IR furnace, the films became (001) oriented on annealing. When calcined in the electric furnace, on the other hand, the films became randomly oriented on annealing. These observations indicate that the heating the gel films from the substrate side in the calcination step at 350 degrees C induces crystallographic orientation in the annealing step at 650 degrees C. The effects of the heating methods on the thermal decomposition of the gel films, and the microstructure and dielectric properties of the fired films were studied. Finally 0.4 mu m thick, (001) oriented PZT films could be successfully prepared by non-repetitive, single-step deposition. The oriented film thus obtained had the remnant polarization 2P(r) of 39 mu C/cm(2) and the dielectric constant epsilon' of 960 +/- 169.

DOI： 10.1007/s10971-008-1801-5

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DOI： 10.1007/S10971-008-1699-Y

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL PUBLISHING  

The effects of heat-treatment conditions on crystallographic orientation was studied on single layer, 0.14-0.19-mu m-thick Pb(Zr0.53Ti0.47)O-3 (PZT) films deposited on Pt(111)/TiO2/SiO2/Si(100) substrates by spin-coating using a Pb(NO3)(2)-Zr(OC3H7n)(4)-Ti(OC3H7i)(4)-polyvinylpyrrolidone (PVP)-CH3COCH2COCH3-CH3OC2H4OH-n-CH3OH solution. The gel films were fired either by placing the coated substrates on an alumina boat and inserting them into an electric furnace of 500 degrees-900 degrees C, or by placing them on a hot mullite plate of 500 degrees-900 degrees C so that the rear side of the substrate was in contact with the hot plate. When the samples were heated by placing on a hot mullite plate, (001)/(100) orientation of PZT occurred even at firing temperatures as low as 600 degrees C, and the films were more completely oriented than those heated by inserting in a furnace along with an alumina boat. This suggests that either the higher heating rates or the heating from the substrate side would promote the oriented crystallization. However, when the gel films were heated up in a near-infrared (IR) image furnace, preferential (001)/(100) orientation was observed even at low heating rates. The Si(100) substrates generate heat in the image furnace, allowing the gel films to be heated from the substrate side, which was suggested by the fact that the films do not absorb the near-IR light while the substrate does. Therefore it can be concluded that heating the gel films from the substrate side is effective for the orientation of the films, by which orientation is realized even in PZT films derived from PVP-containing alkoxide solutions.

DOI： 10.1111/j.1551-2916.2007.02068.x

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Pb(Mg1/3Nb2/3)O-3-PbTiO3 (PMN-PT) thin films were prepared by spin coating using aqueous solutions of metal salts containing polyvinylpyrrolidone, where niobium oxide layers and lead-magnesium-titanium oxide layers were laminated on Pt(111)/TiOx/SiO2/Si(100) substrates and fired at 750 degrees or 800 degrees C. 250 +/- 20 nm thick 0.7PMN-0.3PT thin films of a single-phase perovskite could be prepared, and the film fired at 750 degrees C had dielectric constants and dielectric loss of 1900 +/- 350 and 0.13 +/- 0.03, respectively, exhibiting polarization-electric field hysteresis with a remanent polarization of 5.1 mu C/cm(2) and a coercive field of 21 kV/cm.

DOI： 10.1111/j.1551-2916.2007.01910.x

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Hydroxypropylcellulose (HPC)-titania hybrid thin films were prepared by sol-gel method where titanium tetraisopropoxide Ti(OC3H7i)(4) was hydrolyzed under acidic conditions in the presence of HPC, followed by dip-coating and drying at 120 degrees C for 24 h. The viscosity average molecular weight of HPC was 55,000-70,000 or 110,000 150,000, and the TiO2/(HPC + TiO2) mass ratio ranged from 0 to 1, which was calculated on the assumption that all Ti( OC3H7i)(4) is converted into TiO2. The films were 0.35-1.0 mu m thick, transparent in visible region and opaque in ultraviolet (UV) region, where the optical absorption coefficient in UV region increased with increasing titania content. The refractive index increased with increasing titania content, ranging from 1.6 to 1.8 for the hybrid thin films. The pencil hardness increased from 6B to 5H, the durability in hot water significantly increased and the contact angle of water on films increased from 35 degrees to 89 degrees with increasing titania content. Crack-free films could be deposited on organic polymer substrates irrespective of titania or HPC contents, where cracking did not occur at higher HPC contents even when the substrate was bent.

DOI： 10.1007/s10971-007-1607-x

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Ba(Ti1-x Sn-x)O-3 (x = 0.10 or 0.15) thin films were deposited on Si(100) and Pt(111)/TiOx/SiO2/Si(100) substrates via sol-gel spin-coating. Crack-free thin films could be obtained by single-step deposition, where the thickness was about 0.46 and 0.29 mu m at 1000 and 2000 rpm, respectively. Circular delaminated parts 100 mu m in diameter, however, tended to appear in thicker films deposited at 1000 rpm. On both kinds of substrates, the films were crystallized between 500 and 600 degrees C, where the perovskite phase emerged as the primary phase, and the formation of single-phase perovskite was basically achieved between 700-800 degrees C. The films deposited on Pt(111)/TiOx/SiO2/Si(100) substrates, however, tended to have small SnO2 and BaCO3 diffraction peaks, which decreased with increasing spinning rate. The dielectric properties were evaluated on the films deposited on Pt(111)/TiOx/SiO2/Si(100) substrates at 2000 rpm. The films prepared by single-step depositions had dielectric constants of 350 and 230, and dielectric loss of 0.30 and 0.10 at x = 0.1 and 0.15, respectively. The films prepared by two time deposition had dielectric constants of 450 and 250, and dielectric loss of 0.21 and 0.19 at x = 0.10 and 0.15, respectively.

DOI： 10.1007/s10971-007-0772-2

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DOI： 10.2109/JCERSJ2.115.556

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DOI： 10.1007/S10971-007-9999-1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL PUBLISHING  

Silica gel films were deposited by spin coating on single-crystal Si wafers using an acid-catalyzed Si(OC2H5)(4) solution as a coating solution. The gel films were heated at various rates, where in situ stress measurement was conducted. In-plane tensile stress developed during the course of heating, and was found to be larger at lower heating rates at temperatures up to 350 degrees C. The larger stress was thought to cause cracking at lower temperatures, which was previously observed at lower heating rates in in situ observation. The larger stress at lower heating rates was basically ascribed to the larger degrees of densification, which was revealed in the larger extent of reduction in thickness as well as in Si-OH/Si-O-Si and O-H/Si-O-Si infrared absorption band area ratios at lower heating rates. The difference in stress at different heating rates appeared to originate mainly in the difference observed at low temperatures below 130 degrees C, suggesting that the heating rate particularly affects the densification that occurs via solvent evaporation. The increment in stress was reduced over 400 degrees C when the heating rate was low, which was thought to result from the higher degree of densification already achieved below 400 degrees C as well as the structural relaxation occurring at such high temperatures.

DOI： 10.1111/j.1551-2916.2006.01107.x

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Language：English   Publisher：The Ceramic Society of Japan  

Perhydropolysilazane (PHPS) films ca. 0.2μm in thickness were deposited by spin-coating on Si (100) and silica glass substrates. The PHPS films obtained were suspended over aqueous ammonia of various concentrations for various periods of time at room temperature. The Si-H and N-H infrared absorption peaks decreased, while the Si-O-Si peaks increased, and the nitrogen content decreased from 33.6 to 0.5atomic%, suggesting that PHPS-to-silica conversion occurs on the exposure treatment. The refractive index decreased from 1.56 to 1.48, and the contact angle decreased from 94 to 67°on the exposure treatment. The changes in infrared absorption spectra and in refractive index were more significant when the as-deposited PHPS film was suspended over aqueous ammonia of higher concentrations, indicating that the use of aqueous ammonia of higher concentrations for exposure treatment is more effective in PHPS-to-silica conversion. As the PHPS-to-silica conversion proceeded, the durability of the films in hot water increased, evidenced in both series of films subjected to the exposure for various periods of time and those suspended over aqueous ammonia of various concentrations. When the exposed film was fired at 900℃, the nitrogen content further decreased from 0.5 to 0.01atomic%, the refractive index decreased from 1.48 to 1.45, and the contact angle decreased from 67 to 29°, all of which approached those of pure and dense silica glass. These changes observed on firing suggest that the silica thin films obtained by the exposure treatment at room temperature are not identical to pure and dense silica glass.

DOI： 10.2109/jcersj.114.517

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

Perhydropolysilazane (PHPS) films ca. 0.2 mu m in thickness were deposited by spin-coating on Si (100) and silica glass substrates. The PHPS films obtained were suspended over aqueous ammonia of various concentrations for various periods of time at room temperature. The Si-H and N-H infrared absorption peaks decreased, while the Si-O-Si peaks increased, and the nitrogen content decreased from 33.6 to 0.5 atomic%, suggesting that PHPS-to-silica conversion occurs on the exposure treatment. The refractive index decreased from 1.56 to 1.48, and the contact angle decreased from 94 to 67 degrees on the exposure treatment. The changes in infrared absorption spectra and in refractive index were more significant when the as-deposited PHPS film was suspended over aqueous ammonia of higher concentrations, indicating that the use of aqueous ammonia of higher concentrations for exposure treatment is more effective in PHPS-to-silica conversion. As the PHPS-to-silica conversion proceeded, the durability of the films in hot water increased, evidenced in both series of films subjected to the exposure for various periods of time and those suspended over aqueous ammonia of various concentrations. When the exposed film was fired at 900 degrees C, the nitrogen content further decreased from 0.5 to 0.01 atomic%, the refractive index decreased from 1.48 to 1.45, and the contact angle decreased from 67 to 29 degrees, all of which approached those of pure and dense silica glass. These changes observed on firing suggest that the silica thin films obtained by the exposure treatment at room temperature are not identical to pure and dense silica glass.

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二つの溶液、モル比C<SUB>4</SUB>H<SUB>4</SUB>NNbO<SUB>9</SUB>・7.64H<SUB>2</SUB>O : PVP : H<SUB>2</SUB>O = 1.4 : 1.5 : 324なる溶液Aおよびモル比Pb(NO<SUB>3</SUB>)<SUB>2</SUB> : Mg(NO<SUB>3</SUB>)<SUB>2</SUB>・6H<SUB>2</SUB>O : [CH<SUB>3</SUB>CH(O)CO<SUB>2</SUB>NH<SUB>4</SUB>]<SUB>2</SUB>Ti(OH)<SUB>2</SUB> : PVP : H2O = 3.3 : 0.7 : 0.9 : 1.5 : 314なる溶液Bを調製した。ただし、鉛は化学量論量の10 %過剰とした。まず溶液Aを用いてPt(111)/TiO<SUB>2</SUB>/SiO<SUB>2</SUB>/Si(100)基板上にスピンコーティングし、種々の温度で仮焼してニオブ酸化物膜とした。次に溶液Bをニオブ酸化物膜上にスピンコーティングし、種々の温度で仮焼・焼成してPMN-PT薄膜を得た。1回のコーティング操作により作製した膜の厚さは約0.34 μｍであり、焼成温度800℃でペロブスカイト単一相となった。また、誘電率、誘電損失およびP-Eヒステリシスの評価を行った。

DOI： 10.14853/pcersj.2006F.0.399.0

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Grant-in-Aid for Scientific Research

DOI： 10.1007/S10971-006-9213-X

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Acetylcellulose (AC)/silica composites were prepared by sol-gel method in an attempt to realize materials with Young's moduli and bending strengths similar to those of cortical bones. Si(OCH3)(4) (TMOS)-AC-H2O-HNO3-tetrahydrofuran-CH3OC2H4OH solutions were allowed to be gelled, where AC/TMOS mole ratios were defined for AC monomers, and the gels were dried at 30-70 degrees C to obtain composites. The composites prepared from solutions of mole ratios of AC/TMOS = 0.5 and 1.0 were composed of micrometer-sized particles rich in silica surrounded by the matrix rich in AC. The composites from solutions of AC/TMOS = 2.0, on the other hand, the interface between the particles and the matrix was much less distinct. All the composite samples showed good machinability, which could be cut into 5 mm x 2 mm x 4.4 mm rectangular specimens by an electric saw without cracking or fracture. The specimens were subjected to three-point bending test, where the degree of plastic deformation and the fracture strain increased, and Young's modulus and bending strength decreased with increasing AC/TMOS ratio in the starting solutions. When the gels were dried at higher temperatures, Young's modulus and strength increased. Young's modulus and bending strength could be varied in the range of 1.8-3.9 GPa and 48-100 MPa, respectively, by varying the AC/TMOS ratio in solutions and the drying temperature. (c) 2005 Springer Science + Business Media, Inc.

DOI： 10.1007/s10853-005-4413-2

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Fe2O3-Nb2O5 coating films of various Nb/(Fe + Nb) mole ratios were prepared on nesa silica glass substrates from Fe(NO3)(3)center dot 9H(2)O - NbCl5 - CH3(CH2)(2)CH2OH - CH3COOH solutions by the sol-gel method. The photoanodic properties were studied in a three-electrode cell with an aqueous buffer solution of pH = 7 as the supporting electrolyte. The crystalline phases identified were alpha-Fe2O3 (Nb/(Fe + Nb) = 0), alpha-Fe2O3 + FeNbO4 (Nb/(Fe + Nb) = 0.25), FeNbO4 (Nb/(Fe + Nb) = 0.5), FeNbO4 + Nb2O5 (Nb/(Fe + Nb) = 0.75), and Nb2O5 (Nb/(Fe + Nb) = 1). When the Nb/(Fe + Nb) mole ratio increased from 0 to 0.25, the crystalline phases changed from alpha-Fe2O3 to alpha-Fe2O3 + FeNbO4, the photoanodic current under white light illumination increased, and the photoanodic current under monochromatized light illumination increased in both visible and ultraviolet regions. When the Nb/(Fe + Nb) ratio increased over 0.25, the crystalline phases changed to FeNbO4, FeNbO4 + Nb2O5, or Nb2O5, and the photoanodic current decreased. The sample consisting of alpha-Fe2O3 and FeNbO4 (Nb/(Fe + Nb) = 0.25) exhibited photoresponse extending to 600 nm and an IPCE of 18% at a wavelength of 325 nm.

DOI： 10.1021/jp058051b

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Fe2O3 thin films containing dispersed Au natioparticles were prepared on nesa silica glass substrates, using Fe(NO)(3)center dot 9H(2)O-HAuCl(4)center dot 4H(2)O-CH3COCH2COCH3-CH3OC2H4OH solutions containing polyvinylpyrrolidone (PVP). The photoanodic properties were studied in a three-electrode cell with the film sample as the working electrode and an aqueous buffer solution of pH=7 as the supporting electrolyte. The An particles increased photoanodic quantum efficiency at wavelengths < 500-600 nm. Quantum efficiency was further increased by modifying the microstructure of the film electrodes through the addition of PVP. The maximum incident photon to current efficiency (IPCE) of about 20% was achieved in an Au-dispersed film prepared from a solution containing PVP. PVP in coating solutions provided the fired films with an increase in size of the grains and voids between them and in donor density, either of which could contribute to the increased IPCE. (c) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tsf.2004.09.063

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Acetylcellulose (AC)/silica and polyvinylpyrrolidone (PVP)/silica composites were prepared by the sol-gel method from Si(OCH3)(4)-AC-HNO3-H2O-tetrahydrofuran-CH3OC2H4OH and Si(OCH3)(4)-PVP-(CH3COOH or NH3)-H2O-CH3OH-CH3OC2H4OH solutions. AC/silica composites were composed of micrometer-sized particles rich in silica and a matrix rich in AC, while PVP/silica composites were single-phase on the SEM length scale. The AC/silica composites exhibited elastic-plastic behavior, and had excellent machinability without chipping on cutting with an electric saw while the PVP/silica composites showed less plasticity and machinability. Young's modulus and bending strength were increased by post-drying, 1.8-2.8 GPa and 49-88 MPa, respectively, for the AC/silica composites, and 1.0-3.9 GPa and 17-79 MPa, respectively, for the PVP/silica composites.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KLUWER ACADEMIC PUBL  

Perhydropolysilazane (PHPS) films were deposited on single-crystal Si substrates by spin-coating using a xylene solution of PHPS, and then suspended over 1 mol L-1 ammonia water at room temperature. The PHPS-to-silica conversion occurring on the exposure to the ammonia water vapor was studied by infrared absorption spectroscopy. Si-H and N-H infrared absorption peaks decreased and Si-O-Si bands increased, showing PHPS-to-silica conversion; the conversion was almost completed in 6 h. The exposed films were soaked in 80degreesC water for 24 h, and the reduction in thickness on soaking was evaluated. The PHPS-derived films suspended over the ammonia water for 6 h exhibited only 2% reduction in thickness on soaking in 80degreesC water. Alkoxide-derived silica gel films dried in the ambient atmosphere or suspended over the ammonia water, on the other hand, exhibited significant reduction in thickness on soaking in 80degreesC water.

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Silica gel films were prepared by spin-coating from Si(OC2H5)(4)-HNO3-H2O-ROH solutions and heated at 200degreesC where ROH= CH3OH, C2H5OH, CH3OC2H4OH and CH3CH(OH)CH2OH. Striations were observed with an optical microscope, and quantitatively evaluated by surface roughness measurement. A decrease in height and an increase in spacing of the striations were observed when alcohols of high boiling points were used. However, even when the boiling point of the alcohols was high, an evolution of the striations did occur on spin-coating films, which disappeared while keeping the film in the ambient atmosphere. Convections, which might be the source of the striations, were observed in sol layers placed on a stationary substrate irrespective of the boiling point of the alcohols.

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Spin-coating was conducted on single-crystal silicon substrates using a xylene solution of perhydropolysilazane (PHPS) to obtain 0.14-mum-thick PHPS films. The PHPS films obtained were suspended over various acidic and basic solutions at room temperature so that they were exposed to the vapors from the solutions. PHPS-to-silica film conversion was studied by infrared absorption spectroscopy, and the stability of the exposed films in hot water was examined by soaking the films in 80 degreesC water. The as-deposited PHPS films were found to be dissolved in water. When the PHPS films were suspended over water, the films were partially converted into silica, but the resultant film had low stability in hot water. Higher degrees of PHPS-to-silica conversion and higher stabilities in hot water were found on exposing the PHPS films to basic or acidic vapors. Exposure to highly basic vapors from aqueous solutions of ammonia and ethylamine was significantly effective in PHPS-to-silica film conversion, which provided silica thin films with high stability in hot water.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

PZT, BaTiO3 and BaBi4Ti4O15 films were prepared on Pt/Ti/SiO2/Si substrates by spin-coating using alkoxide solutions containing polyvinylpyrrolidone (PVP). Deposition and firing of the gel films were performed just once, not repeated. Crack-free, single-phase PZT, BaTiO3 and BaBi4Ti4O15 films as thick as 2.2, 0.77 and 0.40 mum could be prepared, respectively, via non-repetitive spin-coating. The 2.2 mum thick PZT film exhibited P E hysteresis with remanent polarization and coersive field of 21 muC cm(-2) and 90 kV cm(-1), respectively. The dielectric constant of the PZT, BaTiO3 and BaBi4Ti4O15 films were 370, 3 10 and MO, respectively, at 1 kHz. (C)2003 Elsevier Ltd. All rights reserved.

DOI： 10.1016/S0955-2219(03)00402-3

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

alpha-Fe2O3 films containing dispersed Au and Ag particles 5-20 nm in size were prepared on nesa silica glass substrates by the sol-gel method, using solutions of a mole ratio Fe(NO3)(3).9H(2)O: (HAuCl4.4H2O or AgNO3): CH3COCH2COCH3:CH3OCH2CH2OH = 1:0.06:2:20 as the coating solution. The anodic photocurrent-potential characteristics and the action spectra were investigated in a three-electrode cell employing the film electrode as the working electrode. When the film electrode was illuminated with intense white light, the embedded metal particles did not affect the photoanodic properties of the electrode significantly. When the film electrode was illuminated with weak white light or weak monochromatic light, the metal particles, especially Au particles, enhanced the anodic photocurrent; the Au particles embedded in the electrode enhanced the quantum efficiency, IPCE, by about 8 times at a wavelength of 400 nm. Deposition of An particles just on the surface of the Fe2O3 film also increased the photoanodic current, suggesting that the enhanced photocurrent is provided by the An particles on the electrode surface, which are supposed to catalytically promote the transfer of the hole in the conduction band of Fe2O3 to the electrolyte.

DOI： 10.1021/jp0303568

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ZnO thin films were deposited on nesa silica glass substrates via sol-gel method using Zn(CH3COO)(2).2H(2)O-Co(CH3COO)(2) .4H(2)O-polyvinylpyrrolidone (PVP)-diethanolamine-2-methoxyethanol solutions. The effects of the Co2+ ions and PVP in coating solutions on the photoanodic properties of the resultant films were studied by measuring photocurrent potential curves and action spectra in a three-electrode cell with a supporting electrolyte of pH = 9.18. The photoanodic current under xenon lamp light decreased with increasing amount of Co2+ ions due to the decreased quantum efficiency in the UV regions. The photoresponse was extended to wavelengths of ca. 450 nm when the Co/Zn mole ratios were 0.05 and 0.15, while the response to the visible light diminished at Co/Zn > 0.3. The UV photoresponse of Co2+-free ZnO films increased when PVP was added in the coating solutions, where the maximum quantum yield of 0.62 was obtained at a wavelength of 364 nm. On the other hand, the UV photoresponse rather decreased when PVP was added in Co2+-containing solutions. (C) 2003 Kluwer Academic Publishers.

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Language：English   Publisher：The Ceramic Society of Japan  

There are still several problems to be scientifically solved for the "conventional"sol-gel ceramic coating technique to be utilized in industrial scale. Based on the recognition, the author's group studied the stress evolution and crack formation in gel-derived films and the evolution of radiative striations in spin-coating films. Possible modification of the sol-gel technique has also been made for realizing thicker films via noncycled deposition. First, the residual stress was measured on alkoxide-derived silica and titania films deposited on silica glass substrate. The residual stress increased with increasing heat-treatment temperature due to densification. It was demonstrated that the stress in films is not a simple function of the difference in thermal expansion coefficient between the film and the substrate, but is greatly affected by the processing parameters including the amount of water for hydrolyzing alkoxides and the kinds of the chelating agents. Second, in situ observation was conducted on silica and titania gel films deposited on single crystal silicon substrates. Macroscopic cracking occurred in the heating-up stage, suggesting that the cracks are formed by tensile stress generated in films due to densification. Also, such cracking was found to occur at lower temperatures when the films are thick or heated at lower rates. Third, expecting that organic polymers with amide groups like polyvinylpyrrolidone (PVP) can promote structural relaxation and can suppress stress evolution on heating, PVP-assisted sol-gel thin film deposition was proposed. Incorporating PVP in coating solutions, crack-free ceramic thin films including BaTiO_3, PZT and BaBi_4Ti_4O_<15> films over submicron or micron in thickness could be prepared via non-cycled deposition. Finally, radiative striations were quantitatively evaluated by surface roughness measurement, and the effects of the processing parameters on striation evolution were studied. The height and spacing of striations were found to be increased with decreasing spinning rate and with increasing sol viscosity. Striations were also found to be formed even without the rotation of the substrate, suggesting that the substrate rotation is not a necessary condition for evolution of striations. On the assumption that the mechanism of the evolution of striations is the same irrespective of the presence or absence of the substrate rotation, in situ observation of the evolution of striations was conducted on a sol layer placed on a stationary substrate. It was observed that striations are formed on solvent evaporation after the sol was spread, not on proceeding of the sol front towards the outer.

DOI： 10.2109/jcersj.111.624

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

There are still several problems to be scientifically solved for the "conventional" sol-gel ceramic coating technique to be utilized in industrial scale. Based on the recognition, the author's group studied the stress evolution and crack formation in gel-derived films and the evolution of radiative striations in spin-coating films. Possible modification of the sol-gel technique has also been made for realizing thicker, films via noncycled deposition. First, the residual stress was measured on alkoxide-derived silica and titania films deposited on silica glass substrate. The residual stress increased with increasing heat-treatment temperature due to densification. It was demonstrated that the stress in films is not a simple function of the difference in thermal expansion coefficient between the film and the substrate, but is greatly affected by the processing parameters including the amount of water for hydrolyzing alkoxides and the kinds of the chelating agents. Second, in situ observation was conducted on silica and titania gel films deposited on single crystal silicon substrates. Macroscopic cracking occurred in the heating-up stage, suggesting that the cracks are formed by tensile stress generated in films due to densification. Also, such cracking was found to occur at lower temperatures when the films are thick or heated at lower rates. Third, expecting that organic polymers with amide groups like polyvinylpyrrolidone (PVP) can promote structural relaxation and can suppress stress evolution on heating, PVP-assisted sol-gel thin film deposition was proposed. Incorporating PVP in coating solutions, crack-free ceramic thin films including BaTiO3, PZT and BaBi4Ti4O15 films over submicron or micron in thickness could be prepared via non-cycled deposition. Finally, radiative striations were quantitatively evaluated by surface roughness measurement, and the effects of the processing parameters on striation evolution were studied. The height and spacing of striations were found to be increased with decreasing spinning rate and with increasing sol viscosity. Striations were also found to be formed even without the rotation of the substrate, suggesting that the substrate rotation is not a necessary condition for evolution of striations. On the assumption that the mechanism of the evolution of striations is the same irrespective of the presence or absence of the substrate rotation, in situ observation of the evolution of striations was conducted on a sol layer placed on a stationary substrate. It was observed that striations are formed on solvent evaporation after the sol was spread, not on proceeding of the sol front towards the outer.

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TiO2 ceramic coating films were deposited on silica glass substrates by the sol-gel method using aqueous solutions of Ti(SO4)(2) containing polyvinylpyrrolidone (PVP) as the coating solutions. Unless PVP was added to the solution, the wettability of the substrate was poor, leading to failure in gel film formation. When PVP was added to the solution, on the other hand, homogeneous gel films could be deposited on the substrate, which could be converted to crack-free, transparent TiO2 ceramic thin films about 0.1 mum in thickness. The TiO2 films thus obtained had refractive index, porosity, and surface roughness R-a (the arithmetic average deviation of the assessed profile) of 2.68, 2.1%, and 0.94 nm, respectively. For comparison, a TiO2 film was also prepared from an alcoholic solution of Ti(OC3H7i)(4), showing refractive index, porosity, and Ra of 2.65, 3.0%, and 0.98 nm, respectively. These values indicate that the TiO2 films prepared from the Ti(SO4)(2) aqueous solutions containing PVP are as smooth and dense as those prepared from conventional alkoxide solutions. The solutions were found to be stable in viscosity for more than five months at room temperature in sealed containers. Thermal analysis, infrared absorption spectra measurement, and x-ray diffraction analysis indicated that the gel films are converted to ceramic films on firing via (i) vaporization of H2O; (ii) decomposition of H2SO4 and/or vaporization of H2SO4 . H2O; (iii) decomposition of SO42- coordinating Ti atoms and oxidation and decomposition of PVP, the latter of which leads to formation of residual carbons; (iv) oxidation of the carbonaceous residues;and (v) crystallization of the titania phase. During the gel-to-ceramic film conversion, the thickness decreased by 90%.

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Residual stress was evaluated by measuring the substrate curvature for alkoxide-derived silica and titania films deposited on silica glass substrates. The residual stress was tensile, increasing with increasing heat-treatment temperature. The stress in fired films was affected greatly by water/alkoxide ratio and chelating agents in starting solutions. Secondly, in situ observation was made on cracking of gel films subjected to heat-treatment. Silica and titania gel films deposited on silicon wafers were cracked in the heating-up stage at temperatures of 100degrees-400degreesC, depending on the film thickness and heating rate. Larger thickness and lower heating rates were found to lower the cracking onset temperature. Finally, organic polymers with amide groups were demonstrated to increase the uncracking critical thickness. The polymers include polyvinylpyrrolidone and polyvinylacetamide, allowing single layer ceramic coating films over 1 mum in thickness to be formed without cracking.

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PZT thin films were prepared on silica-glass substrates from Pb(CH3COO)(2).3H(2)O-Zr(n-OC3H7)(4)-Ti(i-OC3H7)(4)-H2O- CH3COOH-CH3OC2H4OH-n-C3H7OH solutions containing polyvinylpyrrolidone (PVP) via nonrepetitive dip-coating or spin-coating. The thickness of the gel films was varied by changing the substrate withdrawal and rotation speeds, and the crack formation was examined after firing the gel films at 700degreesC. The critical thickness, i.e., the maximum thickness achievable without crack formation, was maximized at a PZT/alkoxide mole ratio of similar to1, where crack-free PZT films as thick as 2 mum could be obtained via single-step deposition. Thermal analysis was conducted on gel films deposited on a glass substrate at similar to25degreesC and then peeled off the substrate. Infrared absorption spectroscopy and X-ray diffractometry measurements were conducted on films deposited on silicon wafers. These analyses revealed that PVP and CH3COO- were thermally decomposed at 250degrees-320degreesC, leaving carbonaceous species, followed by the crystallization of Pb-3(CO3)(2)(OH)(2) at similar to350degreesC. The oxidation of the carbonaceous; species occurred at similar to360degrees-460degreesC; perovskite PZT then was formed at similar to550degreesC. The film thickness decreased greatly at 200degrees-350degreesC, where thermal decomposition of PVP and CH3COO- occurred. The films fired at 700degreesC were rather porous and not very transparent. Preheating the gel films at 100degrees or 200degreesC resulted in particulate microstructure with gaps between the particles, and, at 350degreesC, caused crack formation, both of which further decreased the optical transmittance.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

An aqueous solution-based dip-coating technique was presented for ceramic thin film deposition. Organic polymers with amide groups such as polyvinylpyrrolidone, polyvinyl-acetamide and polyacrylamide, incorporated in aqueous solutions of metal salts, were demonstrated to offer much better wetting of the substrates and gel film formability. Transparent, crack-free TiO2 and ZrO2 thin films of 0.07-0.1 mum in thickness could be obtained from aqueous solutions of Ti(SO4)(2) and ZrCl2O, respectively, containing these organic polymers.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

Lead zirconate titanate (PZT) films were deposited on nesa silica glass substrates by spin coating using a Pb(NO3)(2)-Zr(OC3H7n)(4)-Ti(OC3H7i)(4) solution containing polyvinylpyrrolidone and acetylacetone. The coating solution had stable viscosity for over 1300 h at room temperature. Single-layer PZT films as thick as 0.75 mum could be obtained via single-step spin coating with successive gel film heat treatments at 80, 300, and 700 degreesC. The fired films were optically transparent and crack free, exhibiting P-E hysteresis loops with remanent polarization of 24.6 +/-1.6 muC cm(-2) and coercive field of 95.6 +/-9.8 kV cm(-1). (C) 2001 American Institute of Physics.

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BaTiO3-coating films were prepared from a solution containing poly(vinylpyrrolidone) (PVP) of molar composition Ba(CH3COO)(2):Ti(OC2H5)(4):PVP:CH3COOH:H2O: C2H5OH = 1:1:0.5:27:4:5, via nonrepetitive, single-step dip-coating. The gel films were found to be converted into BaTiO3 films via evaporation of the solvent and CH3COOH below 210 degreesC, decomposition of PVP at 210-360 degreesC, decomposition of CH3COO- below 440 degreesC, and crystallization at 500-610 degreesC. The decomposition of PVP was accompanied by the progress of the condensation reaction, which resulted in significant reduction in film thickness. When the gel films were heated isothermally at 700 degreesC, crack-free BaTiO3 films as thick as 0.9 mum were obtained. When the gel films were heated isothermally at 360 degreesC and then at 700 degreesC, the film became denser. Higher dielectric constants around 290 were found for the film that underwent the isothermal heat treatment at 360 degreesC. A slower rate of PVP decomposition was thought to be the key for the film densification.

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Polycrystalline Fe2TiO(5) films were prepared on nesa silica glass substrates by the sol-gel method, and their photoanodic properties were measured in a three-electrode wet cell with an aqueous buffer solution of pH = 7. Gel films were crystallized into Fe2TiO(5) when fired at greater than or equal to 500 degreesC. The photoanodic current significantly increased when the films were fired at 700 degreesC, and then decreased with increasing firing temperature. Thicker films obtained by repeating the gel film deposition and firing showed smaller photocurrent, and the 50 nm thick film prepared via non-repetitive deposition exhibited the maximum photocurrent. Although the photoresponse was extended to wavelengths near 500 nm, the maximum quantum yield was as low as 0.12 at a wavelength of 340 nm.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

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Language：English   Publisher：Kansai University  

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CiNii Books

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Language：English   Publisher：Kansai University  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KLUWER ACADEMIC PUBL  

Spin coating silica films were prepared from acid-catalyzed tetraethoxysilane (TEOS) solutions, and the magnitude of radiative striations formed on the surface of the resulting films was quantitatively evaluated by measuring surface roughness using a contact probe profilometer. Wave-like transverse profiles were obtained on the films prepared. Surface roughness parameters, Ra (arithmetical mean deviation), Rz (ten point height of irregularities) and S (mean spacing of local peaks), were determined. When the gel films were heated at higher temperatures (less than or equal to 500 degreesC), the film thickness decreased up to 22%, while none of Ra, Rz or S varied with heat-treatment temperature, indicating that the surface of the films is already densified at room temperature. Higher substrate rotation speeds caused decrease in Ra, Rz and S, revealing that the striations decreased both in amplitude and wavelength. Application of viscous sols aged for longer periods of time resulted in increased amplitude (Rz) of striations without change in wavelength (S).

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KLUWER ACADEMIC PUBL  

BaTiO3 and PZT films were prepared from alkoxide-acetate solutions containing polyvinylpyrrolidone (PVP) by non-repetitive dip-coating. It was demonstrated that PVP incorporated in gel films suppresses crack formation during heating and increases the critical thickness, the maximum thickness achievable without crack formation via single-step deposition. Using PVP crack-free BaTiO3 and PZT films 1.2 and 0.5 mum in thickness could be prepared, respectively, via single-step dip-coating. The films were fairly transparent and dense in microstructure. The tensile stress in heat-treated BaTiO3 films was also demonstrated to decrease significantly by incorporating PVP in gel films.

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In the present study n-type and p-type transparent conductive TiO2 films were prepared by using sol-gel method. The n-type TiO2 films were obtained by using Ti(OC3H7i)(4) solutions co-doped with Ru and Ta. The films were uniform and transparent in all the conditions, and their crystalline phases were anatase when HCl or HNO3 was used as a catalyst. The resistivity decreased with increasing Ta content and increased with increasing Ru content. Most of the films showed resistivity minima at a heat-treatment temperature of 700 degreesC. The lowest resistivity of 10(1) similar to 10(2) Omega cm was attained. The p-type TiO2 films were obtained by using Ti(OC3H7i)(4) solutions co-doped with Co and Nb (Sb). The films were also uniform and transparent when AcAc was used, while samples heat-treated at 800 degreesC became opaque when HCl was added. Rutile single phase appeared when the films were heat-treated at 700 degreesC. Logarithmic resistivity of films co-doped with Co and Nb was directly proportional to the reciprocal absolute temperature. On the other hand, the slopes for films co-doped with Co and Sb were different below and above 200 degrees -220 degreesC. The activation energy at the low-temperature region is as low as 0.17 eV, and the resistivity at room temperature is 10(4) similar to 10(5) Omega cm.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CERAMIC SOC  

BaTiO3 coating films were prepared from Ba(CH3COO)(2)-Ti(OC3H71)(4)-H2O-CH3COOH-C3H7OH solutions containing poly(vinylpyrrolidone) (PVP) via single-step, nonrepetitive dip coating. The critical thickness-i.e., the maximum film thickness achieved without crack formation via nonrepetitive dip coating-was successfully increased by incorporation of PVP in the precursor solution. Relatively dense, crack-free BaTiO3 films &gt;1 mu m in thickness were achieved via single-step deposition using a solution containing PVP of average molecular weight of 630 000. Incorporation of an excess amount of PVP, however, led to a decrease in the critical thickness. High-molecular-weight PVP was more effective in increasing the critical thickness, whereas N-vinyl-2-pyrrolidone monomers did not affect the critical thickness. Stepwise heating of the gel films resulted in increased optical transmittance of the films, accompanied by film densification.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Porous thin films composed of spherical TiO2 particles of 0.6-0.7 and 0.3-0.4 mu m in diameter were prepared from Ti(OC2H5)(4) solutions containing HPC (hydroxypropylcellulose) and HNO3, respectively, and the photoelectrochemical properties as a photoanode were investigated in a wet cell. The electrode samples showed higher anodic photocurrent and higher UV photoresponse than relatively dense TiO2 thin film electrodes prepared by dip-coating, and exhibited weak but distinct visible light photoresponse. These experimental results show that the submicron colloidal electrodes have high specific surface area effective for the photo-induced redox reactions. It also suggests the formation of the band bending that contributes to the photocurrent generation. The colloidal electrodes prepared from the HPC-containing solution were found to exhibit higher anodic photocurrent than those from the HNO3-containing solution, probably because of the larger amount of Ti3+ species and mesopores formed in the former electrodes. The effects of post-heat-treatment on the photoanodic properties were also investigated. (C) 2000 Elsevier Science S.A. All rights reserved.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：MATERIALS RESEARCH SOCIETY  

BaTiO3 and PZT films were prepared by single-step dip-coating tom alkoxide-acetate solutions containing polyvinylpyrrolidone (PVP). Crack-free BaTiO3 and PZT films over 1 mu m in thickness were obtained via single-step deposition. Stepwise hearing of the gel films was found to improve densification of BaTiO3 films, reducing the thickness and increasing the optical transmittance, which was not, however, the case with PZT films, where the stepwise heating rather induced crack formation, leading to degraded transmittance. Residual stress was evaluated on spin-coating BaTiO3 films by measuring the substrate curvature, where a significant reduction in tensile stress was found to be caused by PVP.

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DOI： 10.1016/S0142-9612(99)00201-X

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

BaTiO3 coating films were prepared from Ba(CH3COO)(2)Ti(OC3H7i)(4)-H2O-CH3COOH-(C7OH)-O-i solutions containing poly(vinylpyrrolidone) with average molecular weight of 630000. Formation of crack-free BaTiO3 films 1.2 mu m in thickness was successfully achieved via single-step, nonrepetitive dip-coating. The film had relatively dense mocrostructure in SEM scale and transmitted visible light.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KLUWER ACADEMIC PUBL  

PLZT((Pb,La)(Zr,Ti)O-3) ceramic fibers were prepared by the sol-gel method from a solution of lead acetate trihydrate, lanthanum isopropoxide, zirconium n-propoxide and titanium isopropoxide containing 2-methoxyethanol as the solvent. The as-drawn gel fibers were pretreated in an autoclave and preheated in flowing H2O vapor prior to the heat-treatment for crystallization. The effects of autoclaving and preheating in flowing H2O vapor on the structure and composition of the resultant fibers were investigated. Optically transparent single phase perovskite PLZT fibers of 5-15 mu m in thickness and 5 cm in length were successfully prepared when the autoclave-treatment and the preheating in flowing H2O vapor were conducted prior to crystallization. These treatments are thought to promote hydrolysis of the organic groups and polycondensation reaction in the gel fibers, leading to the successful formation of dense, crack-free transparent PLZT fibers.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

A design of a gradient bandgap Ti1-xVxO2 thin film electrode for wet-type solar cells is provided. The gradient bandgap film electrodes were prepared by heating stacked layers of varying V/Ti ratios using the sol-gel method. A composition gradient was observed for some of the samples by X-ray photoelectron spectroscopy although it was not very large. For the Ti1-xVxO2 film electrodes, conspicuous visible light photoresponse and photoelectrochemical stability were observed. The photocurrent increased with increasing bias potential. However, the photocurrent onset potentials of the Ti1-xVxO2 film electrodes were more positive than those of TiO2 film electrodes, probably owing to the high surface state density introduced by the diffusion of vanadium ions. (C) 1999 Elsevier Science S.A. All rights reserved.

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Titanium-vanadium oxide films have been prepared by the sol-gel method using a starting solution containing titanium isopropoxide and vanadium(IV) oxyacetyl acetonate. Solid solubility of VO2 in TiO2 matrix and the effects of vanadium incorporation on the crystallization behavior of TiO2 were investigated by an X-ray diffraction analysis. It was found that the absorption edge of Ti1-xVxO2 films shifted to longer wavelengths when x increased. The sol-gel derived Ti0.95V0.05O2 film electrode was found to exhibit a conspicuous photoresponse in the visible region. Moreover, this film electrode was proved to be photoelectrochemically quite stable. (C) 1999 Elsevier Science S.A. All rights reserved.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Taylor and Francis Inc.  

TiO2 gel films were deposited on self-assembled monolayers (SAMs) of octadecy Itrichlorosilane (OTS) and SiO2 glass substrates using Ti(OC3H7 i)4-derived titania sols. It was found that OTS SAM induces precipitation of anatase phase at a rather low temperature of 200°C when a molar ratio of H2O/Ti(OC3H7 i)4 was as low as 0.5 for sol preparation. © 1999 OPA (Overseas Publishers Association) N.V. Published by license under the Gordon and Breach Science Publishers imprint.

DOI： 10.1080/10587259908023416

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DOI： 10.1080/10587259908023417

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Anatase and rutile film electrodes with comparable porosities were prepared by the sol-gel dip-coating method, and the photoelectrochemical properties were studied based on photocurrent measurement and impedance analysis in a three-electrode wet cell. The photocurrent was found to increase with the donor density, both in anatase and rutile electrodes. For the same donor density, however, rutile electrodes exhibited higher photocurrents than anatase electrodes, which was ascribed to the more beneficial bandgap structure of the former. (C) 1998 Kluwer Academic Publishers.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CERAMIC SOC  

Transparent aluminum-doped zinc oxide (ZnO) films were prepared via the sol-gel method on silica-glass substrates from 2-methoxyethanol solutions of zinc acetate and aluminum chloride that contained monoethanolamine. Dip coating was conducted at room temperature, with substrate withdrawal rates of 1.2-7.0 cm/min, After each deposition, the films were heat-treated in air at 200 degrees-450 degrees C for 10 min (pre-heat-treatment). After six to fourteen layers had been deposited, the films were then subjected to annealing in air at 500 degrees-800 degrees C for 1 h (the first post-heat-treatment), followed by annealing in nitrogen at 500 degrees-700 degrees C for 15 min to 4 h (the second post-heat-treatment). All the films obtained were transparent and showed only an extremely sharp ZnO (002) peak in the X-ray diffractometry (XRD) patterns. The effects of the aluminum content, the substrate withdrawal speed, and the heat-treatment conditions on the electrical resistivity of the films were studied. All these factors strongly affected the resistivity. The lowest resistivity value (6.5 x 10(-3) Ohm.cm) was achieved in a film that contained 0.5 at.% aluminum, prepared with a low substrate withdrawal speed (1.2 cm/min), and a pre-heat-treatment of individual layer at 400 degrees C in air and a post-heat-treatment of the entire film at 600 degrees C in air, followed by a post-heat-treatment at 600 degrees C in nitrogen. These preparation parameters also affected the degree of crystal orientation, which was revealed by the intensity of the ZnO (002) XRD peak. Higher crystal orientation was effective in reducing the film resistivity, whereas the higher grain-packing density and possible aluminum segregation were thought to have positive and negative effects, respectively, in reducing the resistivity.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Lead lanthanum zirconate titanate (PLZT, (Pb,La)(Zr,Ti)O(3)) ceramic fibers were prepared by the sol-gel method from a solution of lead acetate trihydrate, lanthanum isopropoxide, zirconium n-propoxide, and titanium isopropoxide that contained 2-methoxyethanol as the solvent. The sols obtained from the solution were concentrated at 156 degrees-174 degrees C for 2 h, Concentration at higher temperatures resulted in more-viscous sols of higher specific gravities. The concentration resulted in the formation of spinnable sols, which had viscosities &gt;10(5) mPa.s and exhibited Newtonian flow properties. These spinnable sols were formed to be so stable that no change in viscosity and spinnability was observed for more than three months when stored in a sealed container at room temperature. Gel-to-ceramic fiber conversion was investigated by means of X-ray diffractometry, infrared spectroscopy, and thermal analysis. Single-phase perovskite PLZT ceramic fibers 5-200 mu m in diameter and &gt;20 cm in length were obtained. Scanning electron microscopy (SEM) observation and Brunauer-Emmett-Teller (BET) measurement showed that heat treatment of the fibers at a lower rate resulted in the formation of fibers of denser microstructure, Although the SEM image of the cross section of the fibers revealed a relatively dense microstructure and a laser beam could be transmitted through a fiber 6 mm in length, BET measurement of the fibers indicated that the fibers had more than a few percent of open porosities, and scattering of light was observed in the laser-beam guiding test.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Transparent conductive TiO2 films doped with Ru and Ta were prepared on SiO2 glass substrates by the sol-gel method using Ti(OC3H7i)(4) solutions with HCl, HNO3 or diethanolamine (DEA) as a catalyst. The films were anatase when HCl or HNO3 was added to the solution. The solution preparation condition, solution composition, dopant content and hear-treatment temperature all affected the electrical resistivity of the resultant films. There was a clear tendency for the film resistivity to become lower when the dopant solution was refluxed and HCl was used as the additive. The resistivity decreased with increasing Ta content, but decreased with increasing Ru content. Most of the films showed resistivity minima at a heat-treatment temperature of 700 degrees C. The lowest resistivity of 10 similar to 100 Ohm cm was attained when only Ta was used as a dopant. (C) 1998 Elsevier Science S.A.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

TiO2 gel films were deposited on three kinds of substrates: (1) a self-assembled monolayer (SAM) of octadecyltrichlorosilane (OTS), (2) a trimethylsilylated (TMS) glass surface and (3) a bare SiO2 glass surface using Ti(OC3H7i)(4)-derived titania sole. It was found that OTS SAM induces precipitation of anatase phase at a rather low temperature of 200 degrees C and accelerates anatase-to-rutile phase transformation when a mole ratio of H2O:Ti(OC3H7i)(4) as low as 0.5 was employed for sol preparation. These effects possibly result from the interaction between the ordered methyl groups of the OTS SAM and the hydrophobic groups of the titania polymers at the gel film/OTS SAM interface. (C) 1998 Elsevier Science S.A.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Coating films containing Au, Ag, Pt and Pd metal colloids have been prepared by sol-gel processing. It is shown that for oxide films the temperature where the metal particles are precipitated by heating in air depends on metal species: 200 degrees C for Au, 600 degrees C for Ag, 800 degrees C for Pt and 1000 degrees C for Pd. The use of reducing atmosphere lowers the temperature for formation of noble metal colloids. This procedure can be used for direct formation of metal colloids from metal ions in the film as well as reduction of oxide particles to metal particles in the film. For an organic-inorganic matrix, noble metal colloids are precipitated by thermal reduction or photo-reduction. Thermal reduction occurs as a result of reduction by decomposing organic matter. Photo-reduction occurs as a result of UV irradiation.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA LAUSANNE  

ZnO films with preferred orientation along the (002) plane were fabricated by the sol-gel method using Zn(CH3COO)(2) . 2H(2)O as starting material. A homogeneous and stable solution was prepared by dissolving the zinc acetate in a solution of 2-methoxyethanol and monoethanolamine. ZnO films highly oriented along the (002) plane were obtained by preheating the dip-coating films at temperatures from 200 degrees-500 degrees C for 10 min after each coating and postheating at temperatures from 500 degrees-800 degrees C for 1 h. The heat-treatment conditions, the withdrawal speed of the substrate, and the film thickness were found to strongly affect the crystallographic orientation, relative density and morphology of the resultant ZnO films. (C) 1997 Elsevier Science S.A.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Rose bengal-deposited TiO2 film electrodes bearing dispersed Ag or Au nanoparticles were prepared by the sol-gel method. The dye-induced visible region photoresponse of the electrodes decreased with increasing Ag content up to a mole ratio of Ag/TiO2 = 0.0207, while the UV photoresponse increased. On the other hand, the dye-induced visible region photoresponse decreased to a less extent by incorporation of a larger amount of Au particles of Au/TiO2 = 0.06, along with decreased UV photoresponse. The effects of the metal particles on the dye sensitization of the electrodes were discussed in terms of band edge fluctuation induced by the surface metal particles, Schottky barriers at TiO2/metal interfaces, and surface plasma resonance.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHAPMAN HALL LTD  

Perovskite La0.5Li0.5TiO3 (LLT) thin films, 0.2-1 mu m thick, were deposited on non-alkali aluminoborosilicate glass substrates (NA substrates) and glass substrates with ITO (indium tin oxide) coatings (ITO substrates) by the sol-gel method. Alkoxide-based solutions containing titanium alkoxide, lithium alkoxide and lanthanum alkoxide and acetate-based solutions containing titanium alkoxide, lithium acetate anti lanthanum acetate, were used as coating solutions. Impurity phases tended to be precipitated on heat treatment in the films derived from the acetate-based solutions. Addition of acetylacetone or partial substitution of lead for lithium in the acetate-based solutions, however, was effective in suppressing the precipitation of impurity phases. Preferred orientation of the LLT (111/2) plane was observed in the films prepared from the acetate-based solutions when NA substrates were used, whereas the employment of the alkoxide-based solutions or ITO substrates and the partial substitution of lead for lithium, I educed the preferred orientation. The electrical conductivity of the films was much lower than the values reported for the sintered materials.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Silica gel coating films doped with Ru(bpy)(3)(2+) complexes were prepared by the sol-gel method from a hydrolyzed tetraethoxysilane solution containing [Ru(bpy)(3)(2+)]Cl-2 . 6H(2)O. UV-visible optical absorption spectra, fluorescence emission spectra, fluorescence efficiency and lifetime, and infrared absorption spectra were measured for the films dried at various temperatures. The fluorescence band attributed to the transition from the metal-to-ligand charge transfer elicited state to the ground state of Ru(bpy)(3)(2+) was found to show blue shift on sol-to-gel film conversion, red shift with increasing drying temperature up to 200 degrees C, and then blue shift again over 200 degrees C. The fluorescence lifetime increased and the fluorescence efficiency decreased with increasing drying temperature. In the as-deposited film, the complexes are thought to be surrounded by the solvent molecules which interact with the silanol groups of the gel network so strongly that the Franck-Condon excited state of the complex may be relaxed to a less extent, giving rise to the blue shift of the fluorescence peak on the sol-to-gel film conversion. During drying up to 200 degrees C the solvent in the gel pores evaporates, leaving the gel pores filled with air; the complexes are just weakly interacting with the gel network, obtaining more freedom of rotation and surrounded by air molecules, which results in the red shift of the fluorescence peak. Over 200 degrees C, the gel pores start to collapse and the complexes are immobilized in the gel network, strongly interacting with and fully surrounded by the silanol groups and/or siloxane chains, which is reflected in the blue shift of the fluorescence peak.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE - INT SOC OPTICAL ENGINEERING  

Surface plasma resonance (SPR) of metal nanoparticles embedded in dielectric media was briefly reviewed on the basis of electromagnetic theory, where how SPR can enhance the oscillating field of light was illustrated. It was stressed that any photoexcitation processes can be enhanced by SPR as long as they occur at SPR wavelength, and this serves a basis for innovative SPR-assisted optical functions. In order to utilize SPR for enhancing a photoexcitation process of interest, SPR characteristics such as wavelengths should be controlled. Sol-gel method was shown to have great advantages in controlling SPR characteristics through controlling the metal particle size, shape and orientation and selecting the surrounding media A recent attempt to develop materials of SPR-assisted photoelectrochemical functions was also described.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

The effects of the solvent used for preparing a coating solution on the photoelectrochemical properties of the sol-gel derived TiO2 film electrodes have been investigated. Three series of TiO2 film electrodes were prepared from three different coating solutions, in which ethanol, ethanol-isopropyl alcohol and ethanol-2-ethoxyethanol were used as a solvent, and Ti (OC3H7i)(4) as a source of TiO2. The photocurrent of each series of TiO2 film electrodes increased with increasing film thickness up to about 1 mu m and became almost invariant beyond that, indicating that a film thickness of about 1 mu m is required for achieving the highest efficiency. The photoelectrochemical performance of TiO2 film electrodes was strongly dependent on the heat-treatment conditions as well as on the composition of the starting solutions. The results obtained were mainly explained in terms of the electrical resistance of the TiO2 film electrodes.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The process of dimerization and disaggregation of rhodamine 6G in tetraethoxysilane-derived silica gel films was studied using UV-visible and fluorescence spectroscopy. Pyranine (8-hydroxy trisulfonated pyrene) was also used as a fluorescence probe to study the chemical evolution in the films during drying. Rh6G dimers were found in the as-deposited films although only monomers were observed in the sols. Larger amounts of dimers were found in the films prepared from the solutions of higher dye concentration and water content. During drying up to 150 degrees C, the dimers changed gradually into monomers. The dimer-to-monomer transformation was explained by the evaporation of the solvent from the films.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The effects of the lithium substitution for copper on the properties of the superconducting YBa2Cu4O8 were studied. Single-phase YBa2Cu4-xLixO8 was successfully prepared by the sol-gel method under ambient pressure over a composition range of 0 less than or equal to x less than or equal to 0.08, while impurity phases appeared at x=0.10 and 0.20. The lattice constants of YBa2Cu4-xLixO8 were almost invariant with increasing lithium content x. The superconducting transition temperature decreased monotonically with increasing x in the range, 0 less than or equal to x less than or equal to 0.08. The suppression of superconductivity was discussed in terms of the impurity effect in the CuO2 planes.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA LAUSANNE  

TiO2 film electrodes with a TiO2 overlayer containing dispersed Au or Ag metal particles were prepared by the sol-gel method, and the effect of the metal particles on the photoelectrochemical properties of the TiO2 electrodes were investigated. An increase in the anodic photocurrent in the visible region was observed for both the Au and Ag particle dispersed electrodes, which was thought to result from the surface plasma resonance of the metal particles. The introduction of Au metal particles, however, reduced the anodic photocurrent in the ultraviolet region, resulting in a decrease of the anodic photocurrent under the illumination of xenon lamp light. On the other hand, for the Ag particle dispersed electrodes, the anodic photocurrent in the ultraviolet region increased and then decreased with an increasing amount of Ag particles. These effects of the dispersed metal particles on the photoelectrochemical properties of the TiO2 electrodes were explained on the basis of the band models.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

ZnO films were prepared on silica glass substrates by the sol-gel method from Zn(CH3COO)(2) . 2H(2)O-2-methoxyethanol solutions containing monoethanolamine (MEA) or diethanolamine (DEA). Smooth and transparent ZnO films were obtained by heating at temperatures from 200 to 500 degrees C for 10 min after each coating and finally at the same temperatures far 1h. The films prepared from coating solutions containing MEA were strongly oriented along the (002) plane. The effects of heating temperature and ethanolamines on the him morphology, grain size distribution and crystallographic orientation are discussed based on X-ray diffraction and scanning electron microscopy.

DOI： 10.2109/jcersj.104.296

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Language：Japanese   Publisher：The Ceramic Society of Japan  

Effects of gold nanoparticle incorporation on the photoanodic properties were studied for fluorescein-, rose bengal-and nile blue A-deposited TiO_2 film electrodes prepared by the sol-gel method. The incorporation of gold particles decreased the dye-induced photoresponse in the visible region, which was ascribed to the retarded electron transport in the conduction band due to the Schottky barriers at titania/gold interfaces. The extent of decrease in photoresponse, however, was the smallest for the electrode sample with rose bengal, whose optical absorption well overlapped the surface plasma resonance of the gold particles. The dipole-dipole coupling between rose bengal molecules and gold particles was thought to enhance the photochemical processes, resulting in smaller reduction in the photoresponse.

DOI： 10.2109/jcersj.104.164

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

Effects of gold nanoparticle incorporation on the photoanodic properties were studied for fluorescein-, rose bengal- and nile blue A-deposited TiO2 film electrodes prepared by the sol-gel method, The incorporation of gold particles decreased the dye-induced photoresponse in the visible region, which was ascribed to the retarded electron transport in the conduction band due to the Schottky barriers at titania/gold interfaces. The extent of decrease in photoresponse, however, was the smallest for the electrode sample with rose bengal, whose optical absorption well overlapped the surface plasma resonance of the gold particles. The dipole-dipole coupling between rose bengal molecules and gold particles was thought to enhance the photochemical. processes, resulting in smaller reduction in the photoresponse.

DOI： 10.2109/jcersj.104.164

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

The structure of Y-Ba-Si-O-N glasses is investigated by neutron diffraction, and their physical and chemical properties are measured. It is found from the analysis of the radial distribution functions that nitrogen atoms exist as a mixture of two-coordinated and three-coordinated states in the glass, and the ratio of the three- to the two-coordinated nitrogens decreases as the nitrogen content increases. The relationship between structure and properties is also discussed.

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Language：English   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

Pseudoboehmite coating films containing dispersed gold nanoparticles were prepared by sol-gel method. A pseudoboehmite sol was prepared by refluxing a mixture of aluminum tri-sec-butoxide and hydrochloric acid, and then tetrachloroauric acid tetrahydrate was dissolved in the resultant sol. Gel films were deposited on slide glass substrates by spin-coating, dried at 120 degrees C, and exposed to hydrazine vapor at room temperature in order to precipitate gold particles in the films. Transmission electron microscopic observation of the coating films revealed precipitation of aligned, elongated gold nanoparticles of aspect ratios of 2-4. The optical absorption due to surface plasma resonance of gold particles, however, did not show any dependence on the direction of polarization, implying that the elongated gold particles are aligned only in a microscopic region.

DOI： 10.2109/jcersj.103.1305

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS  

The effects of the substitution of alkaline earths or Y for La on the structure and electrical properties of LaSrFeO4 with K2NiF4 structure have been investigated. EDTA titration confirmed that Fe3+ was oxidized to Fe4+ in an amount corresponding to that of divalent alkaline earth ions substituted for La3+. The change in the lattice constants was interpreted in terms of the ionic radius of the substituted ions and the Jahn-Teller distortion of the Fe(IV)O-6 octahedra having d(4) electronic configuration. All the substituted LaSrFeO4 samples were semiconducting over the temperature range from 100 to 300 K. The measurement of the Seebeck coefficient revealed that the conduction carriers of LaSrFeO4 were holes and the carrier concentration increased with increasing amount of Fe4+. La(1-x)A(x)SrFeO(4) exhibited a monotonic decrease in resistivity and activation energy for conduction with increasing Fe4+ abundance. The activation energy for conduction did not change by changing the lattice constant where the Fe4+ abundance did not change with various substituents. (C) 1995 Academic Press, Inc.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KLUWER ACADEMIC PUBL  

TiO2 coating films of 0.3-0.4 mum in thickness that contain fine Pd particles have been prepared by sol-gel method using Ti(OC3H7i)4 and PdCl2 as starting materials in an attempt to obtain optical materials that show surface plasma resonance in the visible range. A temperature higher than 900-degrees-C was required for formation of Pd metal particles when the heat-treatment was conducted in air. Heat-treatment of pre-heated amorphous films in air at 800-degrees-C resulted in precipitation of PdO particles, the size of which could be varied by changing the time of heat-treatment, and subsequent heat-treatment in H-2/Ar gas converted the PdO particles into Pd metal particles. Heat-treatment of pre-heated amorphous films in H-2/Ar gas also resulted in precipitation of Pd metal particles. The size of the Pd metal particles precipitated in the films was 6 to 90 nm, depending on the conditions of heat-treatment. The resultant TiO2 films containing Pd metal particles were brownish grey in color and showed optical absorption in the visible range over 400 nm, which is attributed to surface plasma resonance of Pd metal particles.

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Language：English   Publisher：The Ceramic Society of Japan  

Perovskite type NdNiO_<3-y> and Nd_<0.9>Y_<0.1>Ni0_<3-y> were prepared by heating the gel derived powders at 700℃ in flowing oxygen or in air for relatively short heating time of 20h, and the lattice constants, oxygen content, valence state of Ni ions and temperature dependence of the electrical resistance were measured. A new oxygen deficient orthorhombic phase NdNi0_<3-y> was found, which has larger lattice constants and lower metal semiconductor (M-S) transition temperature than the previously known NdNiO_3 phase. By substitut ing Y for Nd in the present NdNiO_<3-y>, the lattice con stants all decreased and the M-S transition tempera ture increased from 130 to 240 K. The changes in the lattice constants and the M-S transition were dis cussed in terms of the ionic radius and the electronic bandwidth,respectively.

DOI： 10.2109/jcersj.102.1005

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

Perovskite-type NdNiO3-y and Nd0.9Y0.1NiO3-y were prepared by heating the gel-derived powders at 700-degrees-C in flowing oxygen or in air for relatively short heating time of 20h, and the lattice constants, oxygen content, valence state of Ni ions and temperature dependence of the electrical resistance were measured. A new oxygen-deficient orthorhombic phase NdNiO3-y was found, which has larger lattice constants and lower metal-semiconductor (M-S) transition temperature than the previously known NdNiO3 phase. By substituting Y for Nd in the present NdNiO3-y, the lattice constants all decreased and the M-S transition temperature increased from 130 to 240 K. The changes in the lattice constants and the M-S transition were discussed in terms of the ionic radius and the electronic bandwidth, respectively.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Silica sol-gel films were prepared by dipping, starting from an acid catalyzed solution of methyltriethoxysilane (MTES) and tetraethoxysilane (TEOS). Silver metal nanoparticles were produced in the silica layer by introducing in the sol-gel precursor solution AgNO3 or AgClO4 center dot H2O. The silver ions were thermally reduced in air at 800 degrees C, giving an intense yellow coating film. The silver metal particles were observed by transmission electron microscopy and X-ray diffraction. The diameter of the silver particles was found to be about 10 nm. Absorption measurements in the UV-Vis were used to evaluate the volume fraction of silver colloids embedded in the silica layer.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Silica coating films of 0.5-0.7 mu m in thickness doped with gold metal particles were prepared by heating gel coating films obtained from solutions of acid-catalyzed methyltriethoxysilane (MTES) and tetraethoxysilane (TEOS) mixture containing chlorauric acid tetrahydrate. Transparent coating films with deep blue, red, and purple colors were obtained. Changes in size and shape of the gold particles with the MTES content were observed. Lower MTES contents gave bigger and non-spherical particles, while higher MTES contents produced smaller and more spherical particles with a more uniform size distribution. The effect of heat-treatment temeprature on the shape, size, and size distribution of the metallic gold particles was also studied.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Control of the optical properties of gel-derived oxide films containing fine metal particles is described. The duration of the aging of Si(OC2H5)(4)-derived sols and the amount of water for hydrolyzing Si(OC2H5)(4) were found to greatly affect the size and the shape of Au particles formed in the silica matrix, and accordingly the optical absorption of the Au/SiO2 composite films. Employing dielectric media with high refractive indices like TiO2 was shown to shift the absorption peak of Au particles to longer wavelengths. Pd/TiO2 and Pt/TiO2 composite films showed absorption in the visible region.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

It was shown that a single phase YBa2Cu4O8 (124-phase) could be formed from gels at 1 arm oxygen pressure, and the mechanism of its formation was elucidated. It was found that there are two key routes for the sol-gel formation of the 124-phase, one involving the tetragonal YBa2Cu3Oy with a low concentration of oxygen defects (tetra-I phase) and the other involving the Ba2Cu3O5.9 as important intermediates of the 124-phase. The rapid formation of these intermediate compounds from the gel was attributed to the small particle size of the oxides and carbonates precipitating at the initial stage of heating. It was thought that the small particles characteristic of sol-gel processing lead to the rapid formation of the intermediate compounds and subsequent precipitation of the 124-phase.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Formation of silica gels composed of micrometer-sized particles from highly acidic solutions of tetramethoxysilane (TMOS) is described. In this method a limited amount of H2O and a large amount of HCl are used in hydrolyzing TMOS. Detailed conditions and the mechanism of the formation of micrometer-sized particles in the solutions are discussed. Applications of the gels are also described.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE - INT SOC OPTICAL ENGINEERING  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHAPMAN HALL LTD  

In order to synthesize transparent, crack-free silica-gel bodies used as supports for organic substances with optical functions such as fluorescent, lasing, photochromic, photochemical hole burning and non-linear optical functions via the sol-gel route, the effects of the composition of the starting solution on the transparency of the gel, the occurrence of cracks and the bulk density of the gel have been investigated for Si (OCH3)4-H2O-CH3OH-HCl and Si (OCH3)4-H2O-CH3OH-HNO3 solutions. It was found that the addition of specific amounts of water and acid gave transparent, crack-free silica gel bodies, which could be used as supports for optically functional organic substances. It was also found that organic substances such as quinizarin and rhodamine B incorporated into these gels were uniformly dispersed at the molecular level.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHAPMAN HALL LTD  

The effects of sulphur substitution for oxygen on the structure and properties of non-superconducting La2-xSrxCuO4, where x = 0.26 and 0.30, have been studied. In La2-xSrx-CuO4-ySy, the sulphur-doped samples exhibit superconducting transition at 37-39 K and a larger Meissner effect than undoped samples. It was found that the superconductivity of La2-xSrxCuO4-yS, is apparently determined by the value of x-y and the strontium concentration region in which La2-xSrxCuO4 shows superconductivity shifts to higher strontium concentrations with sulphur doping.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Silica glass coatings containing dispersed colloidal gold particles have been prepared by dipping a slide, glass substrate into acid-catalyzed tetraethoxysilane (TEOS) solutions containing HAuCl4.4H2O, withdrawing it, and heating it at 500-degrees-C. Effects of the amount of water and/or hydrochloric acid used for hydrolysis of TEOS on the size and state of the gold particles formed have been investigated. Higher HCl contents were effective in suppressing the escape of gold from the film on heating. Gel films derived from the highly acid catalyzed TEOS solutions hydrolyzed with a larger amount of water were transformed into glass coatings containing dispersed gold particles larger in size; gold particles smaller than 200, 280, and 340 angstrom were formed in the silica coatings derived from the solutions of H2O/TEOS mole ratios of 2, 4, and 10, respectively. Soaking of the gel coatings in monoethanolamine (MEA) vapor prior to heat treatment was found to be effective in suppressing the escape of gold from the film and in formation of silica coatings containing smaller gold particles. Silica glass coatings containing dispersed colloidal gold particles smaller than 80 angstrom in diameter could be prepared from highly acidic solutions through the amine vapor treatment.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER CERAMIC SOC  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

The effects of the kind of solvent on the properties of TiO2 coating films prepared by the sol-gel method using titanium isopropoxide (Ti(OC3H7i)4) as the starting material have been investigated. Ethanol, ethanol mixed with isopropyl alcohol, and ethanol with 2-ethoxyethanol were used as the solvents. The kind of solvent was found to affect the crystallization behaviour, microstructure, and photoelectrochemical properties of the resultant TiO2 coating films.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MATERIALS RESEARCH SOCIETY  

Superconducting YBa2Cu4O8 ceramics were synthesized by the sol-gel method using corresponding metal acetates as starting materials, water as solvent, and tartaric acid under 1 atm oxygen pressure. YBa2Cu4O8 powder was obtained as a single phase by heating the gel at 780-degrees-C for 30 h in flowing oxygen. T(c) was 80 K from magnetic susceptibility measurements. Pelletizing and sintering this powder revealed T(c) (onset) of 87 K and T(c) (end) of 78 K from resistance measurements. YBa2Cu4O8 pellets sintered at 780-degrees-C for 30 h in O2 also consist of a single phase with T(c) (onset) of 85 K and T(c) (end) of 75 K.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

Using oxide glasses of compositions xNa2O.(100-x) SiO2(x=20-50 in mol) and 40Na2O.(60-y)SiO2.yAl2O3(y=5, 10 in mol) as base glass, Na-Si-O-N and Na-Al-Si-O-N oxynitride glasses were prepared by melting powder mixture of oxide glass and Si3N4 or AlN, and the effects of the base oxide glass composition on the glass forming ability, the amount of incorporated nitrogen and the chemical durability of oxynitride glasses were studied. It was found in Na-Si-O-N glasses that the lower Na2O content is favorable for the formation of nitrided glass, giving larger glass forming regions. Retained nitrogen content decreased with increasing Na2O content in Na-Si-O-N glasses and with increasing Al2O3 content in Na-Al-Si-O-N glasses. Chemical durabilily of Na-Si-O-N glass increased with increasing of nitrogen content for any Na2O content of the base glass. For Na-Al-Si-O-N system, however, nitrogen incorporation increased or decreased chemical durability, depending on the Al2O3 content and nitrogen content in the glasses or had no appreciable effect.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE - INT SOC OPTICAL ENGINEERING  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHAPMAN HALL LTD  

Glass-ceramic monoliths with a composition of Li2O.Al2O3.4SiO2 have been synthesized by the sol-gel technique using metal alkoxides as starting materials. Heating dried gel monoliths of about 36 mm diameter and height to appropriate temperatures gave glass-ceramic monoliths of about 20 mm diameter and height without the occurrence of cracks, while a melt-derived glass body of the same composition was cracked or softened on heating. The glass-ceramic monoliths obtained by heating gel monoliths at 1000-degrees-C for 40 h were a porous body, whose bulk density and porosity were 1.62 g cm-3 and 34%, respectively. On heating gel monoliths, beta-eucryptite crystals were first precipitated around 750-degrees-C, followed by precipitation of beta-spodumene crystals at 830-degrees-C. At higher temperatures the latter grew at the expense of the former phase. The crystallized specimens exhibited very low thermal expansion coefficient ranging from - 13-12 x 10(-7)-degrees-C-1 at temperatures from room temperature to 700-degrees-C depending on the heat-treatment temperature of gels, indicating that a porous glass-ceramic monolith with ultra-low thermal expansion can be prepared using the present sol-gel method.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHAPMAN HALL LTD  

X-ray radial distribution analysis and Raman spectroscopic measurement were carried out on Na2O.2TiO2 glass prepared by twin-roller quenching method. It is found that four-coordinated Ti4+ ions may be predominant over six-coordinated ones in the present glass. It is also found that the fraction of six-coordinated Ti4+ ions is larger in the present glass than in K2O.2TiO2 and Cs2O.2TiO2 glasses. Poorer glass-forming ability of the Na2O-TiO2 system compared with the K2O-TiO2 and Cs2O-TiO2 systems is ascribed to a larger fraction of TiO6 octahedron for the former system.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHAPMAN HALL LTD  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

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Language：English   Publisher：The Ceramic Society of Japan  

The preparation of superconducting YBa_2Cu_3O_y through sol-gel method was performed using an acetate aqueous solution. Conditions of gelation and conversion of gel to YBa_2Cu_3O_y ceramics were investigated, applying thermal analysis, infrared absorption spectroscopy and X- ray diffraction techniques. Transparent gel was obtained from the acetate solution with cation mole ratio of Y : Ba : Cu=1 : 2 : 3 by adjusting the initial pH of the solution. Formation of Cu metal, Cu_3O and BaCO_3 below 400℃ was found to occur during heat treatment of the gel. Above 600℃ the heated sample turned into a mixture of Y_2O_3, BaCO_3 and CuO, which finally transformed into the single phase of YBa_2Cu_3O_y at 910℃. The resultant material showed good high T_c superconductivity.

DOI： 10.2109/jcersj.96.355

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Language：English   Publisher：The Ceramic Society of Japan  

A possible method for obtaining the superconducting YBa_2Cu_3O_y fiber based on the sol gel process has been presented The gel fibers were directly drawn from homogeneous viscous sol prepared from aqueous acetate solution of the composition, Y : Ba : Cu =1 ; 2 ; 3 in mole. The heat treatment of the gel fibers up to 910℃ in air successfully resulted in the formation of black ceramic fibers of about 10 μm in diameter. The scanning electron micrographs showed a rough and porous nature of the fired fibers.

DOI： 10.2109/jcersj.96.468

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Language：English   Publisher：ELSEVIER SCIENCE BV  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

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Language：Japanese   Publisher：The Society of Materials Science, Japan  

Crystallization behavior was studied in the three series of glasses (a) (35 -x) BaO・xYO_<1.5>・ 65SiO_2, (b) 35BaO・xYO_<1.5>・(65-x)SiO_2 and (c) (25 +x)BaO・10YO_<1.5>・(65-x)SiO_2, with differential thermal analysis (DTA), X-ray diffraction and scanning electron microscopy. Barium silicates with spherulitic structure were main crystals precipitated from these glasses. By comparing DTA curves of powder samples with those of piece samples, it was found that yttrium oxide reduces internal crystallization in the bulk. Stability of glass against heating was evaluated with the interval between the glass transition temperature and the onset temperature for crystallization. Activation energies for crystal growth were determined by the modified Kissinger plot. It was found that YO_<1.5> increases the stability of glass by increasing the activation energy for crystal growth and this was considered to indicate that YO_<1.5> strengthens the glass network. In 35BaO・xYO_<1.5>・(65-x)SiO_2 series, however, the stability of glass decreased sharply when x exceeded 12 mol %, corresponding to the anomalous property change with composition referred to in the previous study.

DOI： 10.2472/jsms.37.1216

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Other Link： https://jlc.jst.go.jp/DN/JALC/00222381185?from=CiNii

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

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Language：English   Publisher：Institute for Chemical Research, Kyoto University  

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Language：English   Publisher：Institute for Chemical Research, Kyoto University  

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Language：Japanese   Publisher：The Japan Institute of Metals  

DOI： 10.2320/materia1962.27.784

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Language：Japanese   Publisher：Japan Society of Powder and Powder Metallurgy  

Superconducting YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7-x</SUB> fibers and coating films have been prepared using solgel method. Homogeneous viscous sol was prepared by concentrating an aqueous solution of metal acetates. Gel fibers of 5μm - 2 mm in diameter and of more than 50 cm in length could be drawn from the sol. Heat-treated fibers had a hollow structure and were fragile, but showed superconductivity of Tc(end) at 73 K. For preparation of YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7-x</SUB> coating films, metal alkoxide solution was prepared using triethanolamine to dissolve copper alkoxide. Repeated application of the solution on a zirconia substrate and heat treatment in O<SUB>2</SUB> resulted in the formation of a superconducting coating film of 1.5 μm in thickness having Tc(end) at 56 K. Factors affecting the properties of the fibers and coating films have been discussed.

DOI： 10.2497/jjspm.35.339

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

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Language：Japanese   Publisher：The Ceramic Society of Japan  

The glass-forming regions in the SiO₂-Li₂O system have been determined by cooling the melts containing 35-81mol% SiO₂ from liquidus temperature to room temperature at cooling rates; <i>Q</i>₁=4×10^-2, <i>Q</i>₂=1.4×10^-1, <i>Q</i>₃=4×10^-1, <i>Q</i>₄=3, <i>Q</i>₅=19, <i>Q</i>₆=4.4×10² and <i>Q</i>₇≅10⁵K/s. In the composition range SiO₂=35-75mol%, the glass-forming region expanded with increasing cooling rate, and the critical cooling rate <i>Q</i>* decreased with increasing silica content, and reached a minimum at SiO₂=75mol%. Phase separation was observed in the composition range SiO₂>70mol% at cooling rates <i>Q</i>₂-<i>Q</i>₅. However, the region in which the phase separation takes place decreased with increasing cooling rate, yet persisting in high silica compositions. A linear dependence was found in the log-log plot of liquidus viscosity η_L against <i>Q</i>*. When the log<i>Q</i>*-logη_L diagrams are compared with the system B₂O₃-Li₂O, the system SiO₂-Li₂O system was found to have a higher liquidus viscosity than B₂O₃-Li₂O system for a given critical cooling rate. The difference in the glass-forming ability between the two systems was analyzed in terms of kinetic parameters based on the crystallization formula, and the poor glass-forming ability in the system SiO₂-Li₂O in comparison with B₂O₃-Li₂O system was elucidated to be due to a smaller fusion entropy in the former. This implies a smaller structural difference upon crystallization of the silicate in comparison with that of the borate.

DOI： 10.2109/jcersj1950.92.20

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分担執筆，第１章１．２．２節

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Language：Japanese   Publisher：Kansai University  

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Language：English   Publisher：Kansai University  

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Language：English   Publisher：Kansai University  

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Language：English   Publisher：Kansai University  

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Language：English   Publisher：Kansai University  

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Language：English   Publisher：Kansai University  

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Language：English   Publisher：Kansai University  

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Language：English   Publisher：Kansai University  

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Language：English   Publisher：Kansai University  

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Language：English   Publisher：Kansai University  

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Language：English   Publisher：Kansai University  

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Language：English   Publisher：Kansai University  

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Language：English   Publisher：Kansai University  

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Language：Japanese   Publisher：養賢堂  

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Language：English   Publisher：Institute for Chemical Research, Kyoto University  

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：AMER CHEMICAL SOC  

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Event date： 2020.3

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Event date： 2020.3