Design and synthesis of thermoelectric oxides with ultralow thermal conductivity by complex cation engineering

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K13996
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 26020:Inorganic materials and properties-related
• Research Institution: Keio University
• Principal Investigator: HAGIWARA Manabu 慶應義塾大学, 理工学部(矢上), 助教 (30706750)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 熱電変換 / セラミックス / 複合イオン / 熱伝導

Outline of Final Research Achievements

This study aimed to develop n-type thermoelectric oxides with a low thermal conductivity by constructing the A-site of perovskite titanate with a complex cation composed of lanthanum and potassium ions. Semiconductive ceramic samples were obtained by the conventional solid-state synthesis process. It was found that obtained samples have a highly reduced thermal conductivity. A pair distribution function analysis by the reverse Monte Carlo method suggested that a nanometer-scale chemical heterogeneity of lanthanum and potassium ions contributes to the reduced thermal conductivity. It was also showed that doping of barium is effective to increase the electrical conductivity.

Free Research Field

無機材料化学

Academic Significance and Societal Importance of the Research Achievements

金属や半導体の熱起電力効果を利用した熱電発電は我が国の消費エネルギーの70%近くを占める排熱の有効利用にむけたキーテクノロジーであるが、熱電変換材料としてはこれまで人体への毒性や高温での不安定性などの問題をもつ重金属系の化合物半導体が使われてきた。本研究によって実証された複合カチオンエンジニアリングによる熱伝導率の低減効果を利用すれば、無害かつ化学的に安定な酸化物を用いた熱電変換材料の開発が可能になると期待される。