Development of Robot System and X-ray Powder Diffraction for Combinatorial Materials Research
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Development of Robot System and X-ray Powder Diffraction for Combinatorial Materials Research 1
Ikuo Yanase, 2Kenjiro Fujimoto, 2Kazunori Takada, 3Takugo Ohtaki, 2Mamoru Watanabe 1 Saitama University, 255 Shimo-ohkubo, Saitama, Saitama, 338-8570, Japan 2 NIMS, AML, 1-1, Namiki, Tsukuba, Ibaraki, 305-0044, Japan 3 Nissei Sangyou Corporation, 1-24-14, Nishi-shinbashi, Minato, Tokyo, 105-9717, Japan
ABSTRACT We developed a combinatorial robot system as the first step of combinatorial approach to wet and dry synthesis of ceramics. In this study, nanoparticles mixtures having maghemite and a small amount of Y2O3 were prepared successively by using the combinatorial robot system. maghemite and Y2O3 slurries were volumetrically and automatically measured and mixed by repetition of sucking and injecting with a micro-pipette attached to the robot arm. The structural phase transition temperature of maghemite to hematite, which was investigated from the exothermic peak in the DTA curve, increased from ca.813K to ca.1093K by 2atom%Y2O3 addition. It was considered that Y2O3 dissolution into the crystal structure of maghemite had an important role on increasing the temperature of the structural phase transition for stabilizing maghemite phase. (Combinatorial, Slurries, Maghemite, Nanoparticles, Phase transition) INTRODUCTION Maghemite (gamma-type iron oxide) is an important material for preparing magnetic recording materials, pigments, catalysts, and gas-sensitive materials [1-3]. Maghemite gas sensors to hydrocarbons such as H2, C2H5OH, CH4, and C2H4 etc, is limited in low temperature due to structural phase transition of maghemite to hematite (arufa-type iron oxide). Therefore, it has been desirable to increase the structural phase transition temperature in case of iron oxide as gas sensors and catalysts. Recently, several results were reported that the structural phase transition temperature of maghemite to hematite was increased by doping Y2O3 to maghemite by liquid methods such as sol-gel methods [4-6]. However it is difficult to investigate the doping effect of various metal oxides on the structural phase transition of maghemite from the liquid process described above. On the other hand, metal oxide nanoparticles are expected to enhance the doping effect because of their high-reactivity and to increase the number of doping oxides if nanoparticles are mixed easily. Slurries including nanoparticles are thought to be useful in case of mixing nanoparticles. An automatic robot system [7] for mixing nanoparticle slurries developed in our laboratory, which is useful for preparing large number of liquid mixtures, was used. The robot system will be used in viewpoint of combinatorial material research [8-17] for synthesis of ceramic powders acquiring a sequence of process such as measuring raw materials and preparing powder mixtures. In this study, nanoparticle slurries were used as starting materials for preparation of
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nanoparticles mixture consist of maghemite and a little amount of metal oxides. And an investigation of
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