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担当区分：筆頭著者   掲載種別：研究論文（学術雑誌）  

DOI： 10.3390/min9120791

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCI LTD  

Lithium cobalt phosphate, LiCoPO4, has attracted much attention as a high voltage cathode material in lithium ion batteries (LIBs). Since this material suffers from very low ion and electron conductivities, the composite structure made with nano-sized LiCoPO4 and carbon can be effectively used as a cathode material. Here, we report a simple mechanical synthesis route for preparing LiCoPO4/C composite granules. The raw materials for LiCoPO4 and carbon were mechanically treated with an attrition-type mill for producing LiCoPO4/C composite granules using a one-step process without employing external heating. With an increase in the amount of carbon used, the primary particle size of LiCoPO4 and the median size of granules were decreased. The first discharge capacity obtained for the LiCoPO4/C prepared with 5 mass% carbon was 105 mA h g(-1), whereas a value of up to 134 mA h g(-1) was obtained for the composite with 10 mass% carbon. We examined the effect of carbon addition on the mechanical synthesis and characteristics of LiCoPO4 powders.

DOI： 10.1016/j.ceramint.2016.10.022

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1252/kakoronbunshu.43.207

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1252/kakoronbunshu.43.213

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.4164/sptj.54.377

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Hexavalent chromium (Cr(VI)) attracted researchers' interest for its toxicity, natural availability and removal difficulty. Nevertheless, its sorption mechanism is not clearly understood yet. In this work, we elucidated the sorption mechanism of the co-precipitation of chromates with ferrihydrite through quantitative analysis. The influence of Cr/Fe molar ratio on sorption was investigated by zeta potential measurements, X-ray diffraction (XRD) and X-ray adsorption fine-structure analysis (XAFS). Coprecipitation at pH 5 showed almost twice the sorption density of adsorption at pH 5. In co-precipitation, a shift of the XRD peak due to inner-sphere sorption of chromate was observed at Cr/Fe molar ratio 0.5. For adsorption, the same peak shift was confirmed at Cr/Fe molar ratio of 1. Zeta potential at pH 5 suggested that the sorption mechanism changed at Cr/Fe molar ratio 0.25 for coprecipitation and at Cr/Fe molar ratio of 1 for adsorption. Fitting of Cr and Fe K-edge extended X-ray adsorption fine-structure suggested that ferrihydrite immobilized Cr(VI) via outer sphere surface complexation for lower Cr/Fe ratios and via inner-sphere surface complexation for higher molar ratios. At higher molar ratios, bidentate binuclear Cr Fe bonds were well established, thus resulting in the expansion of the ferrihydrite structure. (C) 2017 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jhazmat.2017.03.058

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：The Mining and Material Processing Institute of Japan  

The effective use of by-products in large quantities such as desulfurization gypsum and phoshogypsum is required. Ettringite is well-known as one of cement hydrates and it is expected to be used as a functional material having anion removal ability. We focus on the application of by-product gypsum to a raw material of ettringite. In this case, the hydration state of CaSO4 is considered to be important factor to synthesize ettringite effectively. It is of concern to establish the synthesis method of ettringite using various gypsum for adsorbent and to clarify their anion removal abilities to dilute aqueous solution. The purpose of this study is to investigate the synthesis condition of ettringite from gypsum, especially from the viewpoint of formation speed of ettringites and their anion removal abilities. CaSO4?2H2O or CaSO4 was used for calcium and sulfate ion sources to form ettringite. Whereas NaAlO2, crystalline and amorphous Al(OH)3 was used as an aluminum source, respectively. Phoshogypsum was used as raw material of ettringite synthesis. The removal tests of boron in dilute solution (1ppm) were conducted using ettringite synthesized under various conditions. The Ca precipitation percentage in a ettringite synthesis process using CaSO4 was slightly higher than that using CaSO4?2H2O, due to the difference in solubility or reactivity of CaSO4. When NaAlO2 was used, the formation speed of ettringite was found to be the highest among all products synthesized from various aluminum sources. In using phosphogypsum for ettringite synthesis, it was considered that calcium dissolution was a little reduced by the presence of impurity components such as magnesium and iron in phoshogypsum. The ettringites obtained from NaAlO2 and Al(OH)3 showed 17% and 11% of boron removal, respectively. We will report more detailed results and other anion removal abilities using ettringites under various synthesis conditions in our presentation.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：The Mining and Material Processing Institute of Japan  

Zn oxide has a large band gap and is used as a photocatalyst and a fluorescent substance. It is important to control the particle shape according to the application. A change in the band gap of resulting products appears by adding Al ions to Zn oxide. A solid phase method is usually used for synthesis of a complex oxide. However, sintering at high temperature should be required due to the reaction in the solid phase. In addition, it is difficult to control the particle shape because of high temperature. By using Zn-Al composite hydroxide as a precursor, it is possible that a composite oxide will be formed at lower temperature because the metal ions in a precursor are mixed at the ion level. Zn composite oxides were synthesized using Zn-Al composite hydroxides as a precursor in this study. The particle shape and the light absorption characteristics of various Zn composite oxides were investigated. Crystallinity of Zn-Al composite hydroxides as a precursor was improved by applying a hydrothermal treatment. By calcining the precursors after the hydrothermal treatment, the oxides reflecting the particle shape of precursor was formed. It was considered that the crystal structure of precursor was strengthened by the hydrothermal treatment. The light absorption characteristics of the oxides were different with or without the hydrothermal treatment to precursors, suggesting the change in the crystal structure of products. It was found that the particle shape and the light absorption characteristics could be controlled by applying the suitable synthesis condition of precursor and the preferable hydrothermal treatment as a pretreatment.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：The Mining and Material Processing Institute of Japan  

Steelmaking slag is known as by-products discharged from a steel-manufacturing process. It is mainly reused as civil engineering materials, but reusing steelmaking slag due to its chemical composition is limited actually, compared with blast furnace slag. Development of effective usage is required for steelmaking slag. Layered double hydroxide (LDH) is well-known as a functional material having anion exchange ability. Synthesis method of LDH has been investigated using steelmaking slag as a raw material. Fundamental removal properties of slag-LDHs have been also found for toxic anions. However, many engineering problems to be solved are still remained. For example, immobilization of slag-LDHs containing toxic anionic species are important from an engineering aspect. For the purpose of immobilization properties of As(III), Cr(VI) and Se(IV), the slag-LDHs containing toxic anionic species were heated at various temperatures. The dissolution tests were conducted for the heated slag-LDHs containing anionic species. In order to apply the slag-LDHs to a treatment of contaminated soil, As(III) elution behavior from contaminated soil were carried out by a column operation. Dissolution properties of Cr(VI) and Se(IV) from heated slag-LDHs are different from the regent-LDH, and it is a little easy to dissolve them from the heated slag-LDHs. This tendency may be caused by an impurity component in the slag-LDH. About 20% of Si are contained in the slag-LDH. When Si component is removed from the slag-LDH, it is found that the dissolution properties are similar to those of regent-LDH. It is possible to improve the immobilization ability of toxic anions from the slag-LDH by the heat treatment and the removal of Si component. On the other hand, As(III) elution behavior from contaminated soil is clarified by a column operation using the slag-LDH. It is possible from these results to estimate the required amount of slag-LDH for the immobilization.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：The Mining and Material Processing Institute of Japan  

In these days, base metal demand of the world are increasing, however, grade of ore has been decreased. Therefore, the mineral processing of low grade ore and refractory ore are required to be developed more and more. Microwave irradiation has attracted attention as a method to promote liberation of ores and bring selective reaction such as surface oxidation. This research is studied flotation behavior after microwave irradiation to black ore. It has been confirmed that pyrite (FeS2) and galena (PbS) are selectively inhibited by irradiating microwave to the Myanmar black ore in bulk flotation. It is suggested that the two minerals were selectively oxidized by microwaves and inhibited in flotation process. It was confirmed that not pyrite but chalcopyrite and galena have high reactivity to microwaves and generate heat above 600 °C. Mineral specimens of pyrite and galena were irradiated with microwave in prescribed conditions, and the change of the surface morphology was confirmed by Xray diffraction (XRD), Xray Photoelectron Spectroscopy (XPS) and Xray absorption fine structure (XAFS) analysis. From the measurement results, the presence of lead sulfite (PbSO4) was confirmed from the galena irradiated with microwave. Therefore, oxidation reaction occurred by irradiation with microwave, and galena changed to lead sulfite, so it was inhibited by flotation. On the other hand, oxidation was not confirmed in pyrite. It is suggested that it was oxidized by heat from the other high reactive minerals like chalcopyrite or galena.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

In this paper, LiCoO2/Li1.3Al0.3Ti1.7(PO4)(3) (LATP) composite granule as low-cost cathode for all-solid-state lithium-ion batteries was prepared by simple mechanical method using an attrition-type mill. LiCoO2 and LATP were chosen as the active material and the solid-state electrolyte, respectively. The mechanical treatment of LiCoO2 and LATP powders consisting of each nanoparticle provided the homogeneously dispersed composite granule with the granule size of several tens of micrometers. The all-solid-state lithium-ion battery fabricated from this composite granule exhibited the good electrochemical performances compared with that from the LiCoO2 granule without LATP. The capacity retention of approximate to 90% was obtained in the 20 cycles test. The inner dispersed LATP nanoparticles with a high conductivity of lithium ion played a crucial role in operating of the all-solid-state lithium-ion battery. (C) 2015 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

DOI： 10.1016/j.apt.2015.10.013

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN INST METALS  

For the establishment of appropriate recycling process, the delamination of electric components from printed circuit boards (PCBs), which are major components of c-waste, is expected, because some of useful critical metals are concentrated in specific components. However, the knowledge about the mechanism of the delamination process in a drum typed agitation mill is still limited and uncertain. To better comprehend the mechanism, in this study, the particle-based simulation and comminution tests using handmade PCBs were conducted. The behavior of PCBs and the air flow in the mill having flexible chains was simulated by the discrete element method (DEM) coupled with computational fluid dynamics (CFD). To model the shape of PCBs, the particle based rigid body model was introduced into the DEM. Since this model could not directly simulate the breakage phenomena, collision energy was calculated to qualitatively evaluate the comminution performance. In addition, the simulation results were compared with the experimental comminution tests, This study demonstrated the behavior of PCBs and the air flow in the mill, and the effect of the air to comminution process in the mill. It was also shown that the collision energy related to parts collision was better correlated with the experimental results and this correlation can be assumed using first order rate equation, which suggested part detachment was mainly brought by direct collision to parts in the mill.

DOI： 10.2320/matertrans.M-M2016834

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担当区分：筆頭著者   記述言語：日本語   出版者・発行元：高温学会  

DOI： 10.7791/jspmee.5.358

CiNii Books

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DOI： 10.4164/sptj.52.634

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：AMER CERAMIC SOC  

Carbon nanotubes (CNTs) are expected to be used to improve electrical conductivity and to reinforce mechanical properties of many materials. In our previous study, fabrication of CNT-dispersed S13N4 ceramics having high strength succeeded by uniform dispersion of CNTs using bead milling technique. However, their electrical conductivity degraded though the size of CNTs was not changed after bead milling process. The reason for the degradation is that formation of electrically conductive paths due to networking of CNTs was insufficient. In this study, networking of CNTs in ethanol was controlled by adding surfactant. Furthermore, CNT/alumina composites were fabricated by spark plasma sintering and their electrical and mechanical properties were evaluated. From optical microscopic observation, networking of CNTs in the slurry was occurred by adding ammonium polycarboxylate. Electrical conductivity of CNTs dispersed slurry increased with an increase in quantity of the added ammonium polycarboxylate and with an increase in the soaking time due to development of CNT network. Electrical conductivity of the CNT/alumina composites prepared by adding ammonium polycarboxylate were higher than those without ammonium polycarboxylate while having higher strength. The improvement of these properties resulted from homogeneous networking of CNTs formed by adding ammonium polycarboxylate to increase the conduction paths in the sintered body.

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担当区分：筆頭著者   掲載種別：研究論文（学術雑誌）  

Studies on the dispersion of carbon nanotubes (CNTs) in silicon nitride (Si3N4) ceramics to provide the latter with electrical conductivity have been carried out in recent years. The density and the strength of Si3N4 ceramics were degraded, however, because the CNTs prevented Si3N4 from densifying. The CNTs disappeared after firing at high temperatures owing to the reaction between CNTs and Si3N4 or SiO2, or both Si3N4 and SiO2. In order to improve the density and suppress the reaction, sintering aids for lower-temperature densification of Si3N4 are needed. In this study, we added HfO2 as a sintering aid to a Si3N4-Y2O3-Al2O3-AlN-TiO2 system to fabricate CNT-dispersed Si3N4 ceramics at lower temperatures. Furthermore, bead milling was applied to disperse the CNTs homogeneously. Agglomerates of CNTs were pulverized by bead milling without obvious changes in morphology to eliminate larger fracture origins in CNT-dispersed ceramics. As a result of both the addition of HfO2 and bead milling, we successfully fabricated dense CNT-dispersed Si3N4 ceramics with high strength and electrical conductivity. © 2014 The Ceramic Society of Japan and the Korean Ceramic Society.

DOI： 10.1016/j.jascer.2014.02.005

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担当区分：筆頭著者   記述言語：英語   出版者・発行元：The Materials Research Society of Japan  

The preparation of electrically conductive silicon nitride (Si₃N₄) ceramics by dispersing carbon nanotubes (CNTs) has been studied in the recent years. However, the density and strength of Si₃N₄ ceramics was found to deteriorate and the CNTs disappeared after firing at high temperatures because CNTs prevent Si₃N₄ from densification and there is a possibility that the CNTs reacted with the Si₃N₄ or SiO₂. To prevent the CNTs from reacting and disappearing, low temperature densification is required. In this study, HfO₂ was added to a Si₃N₄-Y₂O₃-Al₂O₃-AlN system to fabricate CNT-dispersed Si₃N₄ ceramics at low temperatures. As a result, a sample to which HfO₂ had been added and which was fired at lower temperatures showed higher electrical conductivity and higher bending strength. It was also observed that the mechanical and electrical properties of the ceramics depended on the quantity of added CNTs.

DOI： 10.14723/tmrsj.37.11

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掲載種別：研究論文（学術雑誌）  

The study to give electrical conductivity by dispersing carbon nanotubes (CNT) into silicon nitride (Si 3N 4) ceramics has been carried out in recent years. However, the density and the strength of Si 3N 4 ceramics were degraded and CNTs disappeared after firing at high temperatures because CNTs prevent Si 3N 4 from densification and there is a possibility that CNTs react with Si 3N 4 or SiO 2. In order to suppress the reaction and the disappearance of CNTs, lower temperature densification is needed. In this study, HfO 2 and TiO 2 was added to Si 3N 4-Y 2O 3-Al 2O 3-AlN system to fabricate CNT-dispersed Si 3N 4 ceramics at lower temperatures. HfO 2 promotes the densification of Si 3N 4 and prevents CNT from disappearance. As a result, the sample by adding HfO 2 and TiO 2 fired at lower temperatures showed higher electrical conductivity and higher bending strength. It was also shown that the mechanical and electrical properties depended on the quantity of the added CNTs.

DOI： 10.4191/kcers.2012.49.4.333

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記述言語：日本語   出版者・発行元：資源・素材学会  

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