Development of thermoelectric conversion materials filled with noble gas and new insight into rattling effect

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K14091
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Inorganic industrial materials
• Research Institution: Nagoya University
• Principal Investigator: NIWA Ken 名古屋大学, 工学研究科, 准教授 (40509030)
• Research Collaborator: NOZAKi Tatsumi ; NISHIDOUZONO Keita
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 超高圧合成 / 希ガス / 熱電変換材料 / 遷移金属リン化物

Outline of Final Research Achievements

The high-pressure generation technique was applied to develop new thermoelectric conversion materials. First of all, we have developed and optimized the piston cylinder apparatus for the single crystal growth experiments under high pressures. After the several trials for single crystal growth experiments, we succeeded in the growth of Mn-doped CoP3 single crystals. In addition to the single crystal growth experiments of CoP3, we also succeeded in the synthesis of new transition metal phosphides above the pressure of 20 GPa. Newly synthesized NbP2 is found to crystallize in MoS2-type structure while it gradually transform into another phase after release of the pressure under ambient pressure. Although the ambient metastability of new NbP2 is low, it would offer new insight as the functional materials including the properties of thermoelectronic conversion, superconductivety and catalysis, and further studies will be conducted.

Free Research Field

超高圧物質科学

Academic Significance and Societal Importance of the Research Achievements

本研究では，希ガスをラットラーとして用いた熱電変換材料の開発を目指して研究に取り組んできた．高圧単結晶育成手法の最適化には成功したが，本研究期間内に希ガス充填による熱伝導特性の評価の検証までは至らなかった．しかしながら，超高圧実験技術を駆使することで今までほとんど知られていなかった，高配位ニオブリン化物（NbP2）の合成に成功し，その物質科学を開拓するきっかけを得ることができた．リン化物は化学的にも熱的にも安定で熱電変換材料の他に触媒など幅広い用途が期待されている．本研究により，超高圧力場が過去に無い新たな機能性リン化物の創製に有効であることがわかった．