| Project/Area Number |
17360311
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical properties of metals
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| Research Institution | Nagoya Institute of Technology |
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Principal Investigator |
NISHINO Yoichi Nagoya Institute of Technology, Dpt of MateialsScieice ardEngineaing, Professor (50198488)
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| Co-Investigator(Kenkyū-buntansha) |
SODA Kazuo Nagoya University, Dpt of Qranlum Engineering, Professor (70154705)
IDE Naoki Nagoya University, Dpt of Mateials Sciece and Engineering, Assistant Professor (60262945)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥7,880,000 (Direct Cost: ¥7,400,000、Indirect Cost: ¥480,000)
Fiscal Year 2007: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Fiscal Year 2006: ¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 2005: ¥3,600,000 (Direct Cost: ¥3,600,000)
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| Keywords | Heusler compounds / Pseudogap / Thermoelectric Materials / Seebeck effect / Electrical conductivity / Thermal conductivity / Site oreference / Electron concentration effect / 熱電材料 / ゼーベック係数 |
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| Research Abstract |
The thermoelectric power of Fe_2VA1 can be expected to be well enhanced by doping or off-stoichiometry, because the density of states rises sharply in both sides of the pseudogap. We have investigated the temperature dependence of the Seebeck coefficient and the electrical resistivity in the Fe_2VAI-based alloys, in addition to the measurement of the thermal conductivity at room temperature, to clarify the doping effect on the thermal and transport properties. The compositional variation of the Seebeck coefficient falls on a universal curve, irrespective of the doping elements, when plotted against the valence electron concentration (VEC), instead of the composition of the doping elements. The net effect of doping is most likely to cause an appreciable shift of the Fermi level from the central region in the pseudogap without modifying the band structure in any essential manner. The substitution of heavy atoms certainly acts in favor of the development of thermoelectric materials because of a substantial reduction of the lattice thermal conductivity. Co-doping of heavier atoms is also effective to reduce the lattice thermal conductivity while retaining the low electrical resistivity as well as the large Seebeck coefficient. For the Heusler compound Fe_<2-x>Co_xTiAl with VEC=6, the compositional variation of the Seebeck coefficient is in line with a pseudogap scenario where the off-stoichiometry causes a rigid-band-like shift of the Fermi level from the central region in the pseudogap. The low Seebeck coefficient may be attributed to an atomic disorder between Fe and Co
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