2022 Fiscal Year Final Research Report

Low-dimensional structured heat-flux controlling molecular crystals exhibiting phase transitions

Research Project

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Project/Area Number	20K05535
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Review Section	Basic Section 34010:Inorganic/coordination chemistry-related
Research Institution	Niigata University (2022) Tohoku University (2020-2021)
Principal Investigator	Hoshino Norihisa 新潟大学, 自然科学系, 特任准教授 (30551973)
Project Period (FY)	2020-04-01 – 2023-03-31
Keywords	熱流制御 / 熱電素子 / スピンクロスオーバー錯体 / 固体内分子振動 / 強誘電体 / 有機導体
Outline of Final Research Achievements	In this study, we investigated the creation of heat flow control devices based on complex chemistry and obtained the following results. (1) The thermal conductivities of one-dimensional ferroelectrics NH4HSO4 and RbHSO4 were measured, and it was found that the two crystallographically nearly isostructural materials exhibit completely different heat transfer behaviors depending on the molecular vibration in the crystal. (2) The partially oxidized salt of TCNQ exhibits a large thermoelectric effect due to its one-dimensional band structure. In this work, various organic cations were introduced to TCNQ salts. The reduction of thermal conductivity due to their vibrations and the effects to the performance index of the thermoelectric device (zT value) was clarified. (3) A strong correlation between the spin transition and thermal conductivity was found in the spin crossover complex [Fe(R-salEen)]X for the first time in the world.
Free Research Field	錯体化学・分子磁性・分子科学・有機結晶・構造相転移
Academic Significance and Societal Importance of the Research Achievements	本研究では、分子性結晶の熱伝導度を実際に測定し、構造の次元性や固体内分子運動との相関について明らかにした。このような研究成果は他に類がなく、固体物性研究において有益な手法を提案・実証することに成功したといえる。また本研究において開発した測定装置についても、成果発表論文や総説中において詳細な解説を加えたことで、研究分野の発展に貢献することができたと確信している。また本研究では、スピン状態が熱伝導度と強い相関を持つことや、強誘電体が相転移に伴い熱伝導度変化を大きくスイッチすることを示した。これらの研究成果は新しい熱流制御デバイスの開発を通じて、省エネルギー社会に貢献するものである。