Controlling of thermal and electron transport using high pressure torsion and its application to environmental friendly thermoelectric materials

2021 Fiscal Year Final Research Report

• Project/Area Number: 18H01384
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 19020:Thermal engineering-related
• Research Institution: Kyushu University
• Principal Investigator: Kohno Masamichi 九州大学, 工学研究院, 教授 (50311634)
• Co-Investigator(Kenkyū-buntansha): 塩見 淳一郎 東京大学, 大学院工学系研究科(工学部), 教授 (40451786) ; 生駒 嘉史 九州大学, 工学研究院, 助教 (90315119)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 高圧ひずみ / シリコン / 熱伝導率 / 電気伝導率

Outline of Final Research Achievements

In this research, silicon and silicon germanium mixed materials, which are important semiconductor materials, are subjected to high-pressure torsion process (the fine structure inside the material is deformed by applying high pressure to the material) to introduce metastable phase in the material. The purpose is to control its physical properties by introducing metastable phases (a structure different from the normal structure). It was observed that the thermal conductivity and electrical conductivity of the material changed significantly by high-pressure torsion process. In addition, it was found that also the optical property of the material is affected by the structural changes due to high-pressure torsion process. We also performed theoretical calculation to predict the thermal conductivity of the metastable phase and to understand mechanism of heat transport of the materials.

Free Research Field

熱工学

Academic Significance and Societal Importance of the Research Achievements

高圧ひずみ加工は金属材料の組織を微細化し，その材料強度を向上する手法として以前より用いられてきたが，材料の微細化によって，水素吸蔵合金の高性能化や界面の増加による超伝導材の臨界温度の上昇など，材料の機能性向上にも効果的であることが判明している．本研究では重要な半導体材料である，シリコンやシリコンゲルマニウム混合材料に高圧ひずみ加工を施し，準安定相を導入することで，材料の構造と重要な物性である熱伝導率や電気伝導率の相関を把握したものである．準安定相を制御することにより，従来の材料が有していない新規な物性や機能の発現が期待される．