2022 Fiscal Year Final Research Report
Synthesis and physical property measurements on "uncompensated" thermoelectric semimetal
| Project/Area Number |
21K13878
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 13030:Magnetism, superconductivity and strongly correlated systems-related
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| Research Institution | Nagoya University |
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Principal Investigator |
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| Project Period (FY) |
2021-04-01 – 2023-03-31
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| Keywords | 熱電半金属 / 高移動度 / 低次元系 / 層状遷移金属カルコゲナイド |
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| Outline of Final Research Achievements |
In this study, the origin of the giant thermoelectric power factor of the semimetal Ta2PdSe6 at low temperatures has been investigated in terms of synchrotron X-ray diffraction experiments and element substitution effects. The crystal structure hardly changes between room and low temperatures, indicating that the sign change in thermopower is not due to the change in the band structure. The effect of Nb substitution at the Ta site was investigated using a minimal two-carrier model. It was found that the magnitude of the mobility of holes relative to electrons could explain the substitution effect quantitatively. This suggests a guideline for the design of new thermoelectric materials for low temperatures using high-mobility semimetals.
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| Free Research Field |
固体物性物理
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| Academic Significance and Societal Importance of the Research Achievements |
本研究成果の学術的意義は、Ta2PdSe6という半金属物質が従来の半導体熱電材料と桁違いに大きな熱電性能を示すこと、さらにその性能が移動度に起因した"非補償性"という新しい設計指針にあることを示したことである。従来の熱電物質開発においては、超伝導デバイスの電子冷却や冷熱の利用が期待される低温(T < 200 K)における熱電物質の研究はあまり進んでいなかったが、この研究成果により、これまでほとんど手つかずで残されていた半金属物質群の鉱脈からより有望な物質の発見につながるかもしれない。将来的には超伝導素子の局所冷却・無冷媒動作などに革新的な影響を与えることも期待される。
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