| Project/Area Number |
06555266
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 試験 |
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| Research Field |
無機工業化学
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
SHIMADA Masahiko Tohoku University, Institute for Advanced Materials Processing, Professor, 素材工学研究所, 教授 (80029701)
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| Co-Investigator(Kenkyū-buntansha) |
IMANISHI Yuichiro NGK Insulators, LTD,Ceramic Materials Laboratory, Maneger, 研究開発本部機能部品研究所, グループリーダー
ENDO Tadashi Tohoku University, Faculty of Engineering, Professor, 工学部, 教授 (30176797)
TAKIZAWA Hirotsugu Tohoku University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (90226960)
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| Project Period (FY) |
1994 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥13,500,000 (Direct Cost: ¥13,500,000)
Fiscal Year 1996: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1995: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1994: ¥11,000,000 (Direct Cost: ¥11,000,000)
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| Keywords | Pressure sintering / Iron silicides / Oriented grain / Anisotropic thermoelectric power / Anisotropic electric conductivity / ゼ-ベック係数 / 高温熱電特性 |
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| Research Abstract |
beta-Fe_<1-x>Ru_xSi_2 solid solution was synthesized by solid state reaction at 1100ﾟC for 48h and subsequect annealing at 850ﾟC for 168h in an evacuated silica tube. Single phase solid solution was obtained in the composition range 0*x*0.1. The thermal stability range of the beta-phase extended to higher temperature region by partial substitution of Ru atom. The thermoelectric properties of Cr or Co-doped B-Fe_<1x>Ru_xSi_2 strongly depend on the sinthering conditions. The samples with optimum thermoelectric properties are obtaind by high-pressure sintering at 3 GPa and 800ﾟC for 1h. Seebeck coefficient for X-axis perpendicular to applied pressure was superior to that for Z-axis parallel to applied pressure. The anisotropy of electrical conductivity was opposite tendency comparing with the results of Seebeck coefficient. The optimum compositions are found to be Fe_<0.92>Ru_<0.05>Cr_<0.03>Si_2 and Fe_<0.92>Ru_<0.05>Co_<0.03>Si_2 for p-type and n-type materials, respectively. The power factors (sigmaalpha_2) of these materials are higher than that of beta-FeSi_2 based materials. The mechanism for the anisotropy of thermoelectric properties was examined. As a result, it is considered that the model of oriented-grain microstructure is most possible factor to introduce the anisotropy of thermoelectric properties. In this model, a very few amounts of impurities (FeSi, amorphous Si etc.) were located at grain boundaries. Both oriented-grains and impurities in microstructure play an important role to introduce the anisotropy of thermoelectric properties.
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