Analysis of a local distortion around dopant inducing a high thermal resistance of thermoelectric materials based on the synchrotron radiation

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K14801
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Physical properties of metals/Metal-base materials
• Research Institution: Nagoya Institute of Technology
• Principal Investigator: Kimura Koji 名古屋工業大学, 工学(系)研究科(研究院), 助教 (20772875)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 熱電材料 / フォノン / 放射光X線 / 蛍光X線ホログラフィー / X線非弾性散乱

Outline of Final Research Achievements

Heavy element doping is a widely adopted strategy to improve a performance of thermoelectric materials, which can directly convert heat into electricity. In particular, the doping effectively enhances the thermal resistance, which is proportional to the figure of merit of thermoelectic materials.
In this study, the underlying mechanism was investigated in detail by using synchrotron radiation for the Fe2VAl Heusler type thermoelectric material doped with a heavy element of Ta. We observed the so-called resonant mode originating from the Ta doping, and found that the thermal vibration of Ta is remarkably different from that of the matrix element. This difference disturbs the propagation of the phonons, the carrier of the heat, and consequently should contribute to the enhancement of the thermal resistance.

Free Research Field

X線物理学

Academic Significance and Societal Importance of the Research Achievements

熱電材料は、廃熱を直接電気に変換できることから、エネルギー問題解決のキーとなる材料の一つである。熱電変換効率向上のために元素ドープがこれまで多くなされてきたが、本研究では新たに、ドープした元素の振動状態に着目した性能向上効果を示唆することが出来た。これは、新しい材料設計戦略の基礎となる成果であり、ドーパントの種類や量を従来とは異なった観点から最適化することにつながると期待される。