| Project/Area Number |
16560585
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Inorganic materials/Physical properties
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| Research Institution | Tohoku University |
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Principal Investigator |
TAKAHASHI Junichi Tohoku University, Institute of Multidisciplinary Research for Advanced Materials, Research Associate, 多元物質科学研究所, 助手 (20261472)
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| Co-Investigator(Kenkyū-buntansha) |
YAMANE Hisanori Tohoku University, Center of Interdisciplinary Research, Professor, 学際科学国際高等研究センター, 教授 (20191364)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2005: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2004: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Keywords | one-dimensional structure / thermoelectric materials / cobalt oxides / single crystals / flux method / electric resistivity / Seebeck coefficient / power factor |
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| Research Abstract |
Columnar single crystals of Ca_3Co_2O_6 and doped (Ca,Bi)_3(Co,M)_2O_6 (M=Fe,Cu) were synthesized in a molten K_2CO_3 flux. The Ca_3CO_2O_6 single crystals showed a needle-like shape and the elongated direction was confirmed to have the c axis of the crystal structure. Electric resistivity (ρ) and Seebeck coefficient (S) of the crystals were measured along the c axis direction of the crystal structure from room temperature to over 1000K in air. The Ca_3Co_2O_6 (c axis) showed p-type semiconducting behavior with ρ values of 2.0 Ωcm at room temperature and 0.013 Ωcm at 1000 K. The S values were +165 μV^<-1>K^<-1> at 300 K, +300 μV^<-1>K^<-1> at 440 K, and +169 μV^<-1>K^<-1> at 1000 K. The power factor (S^2ρ^<-1>) increased with increasing temperature and attained 0.233 mW^<-1>m^<-1>K^<-2> at 1000 K. The (Ca,Bi)_3(Co,M)_2O_6 (M=Fe,Cu) single crystals with a pseudo-one-dimensional structure were synthesized by the flux method using K_2CO_3 and p-type semiconducting behavior for the c axis of the single crystals was seen in the temperature range from room temperature to over 1000 K in air. The doping of Fe and Cu contributed to improve the power factor.
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