Clarification of giant thermal expansion phenomenon in amorphous Ce-Mn alloys

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K05239
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 29010:Applied physical properties-related
• Research Institution: Muroran Institute of Technology
• Principal Investigator: Amakai Yusuke 室蘭工業大学, 大学院工学研究科, 准教授 (50400065)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 巨大熱膨張 / アモルファス合金 / セリウム合金 / 直流高速スパッタ法 / 熱膨張測定

Outline of Final Research Achievements

The purpose of this study is to clarify the mechanism of the giant thermal expansion observed in amorphous Ce-Mn alloys from the viewpoints of magnetic and electronic properties. We considered that strongly correlated electronic states involving Mn spins or Ce 4f electrons are important for the appearance of giant thermal expansion. However, when Ce is replaced by Y, a decrease in the thermal expansion coefficient is observed near room temperature, and the effect of magnetic field is hardly observed in the thermal expansion in magnetic field and specific heat measurements. Therefore, it is clear that the presence of Ce is important for the giant thermal expansion coefficient and that Mn spins have no significant effect on the increase in the thermal expansion coefficient.

Free Research Field

固体物理学

Academic Significance and Societal Importance of the Research Achievements

巨大熱膨張現象は，ヒートスイッチのようなセンサー材料として可能性を有するが，熱膨張が大きく違う物質の接合の際の緩衝材(例えばヒートシンク)や巨大熱膨張の出現に伴う巨大な比熱を利用した蓄熱材料などへの応用も期待されることに創造性がある。Ce-Mn合金の場合，組成変化や置換によりで熱膨張係数を変化させたり，熱膨張係数の温度依存を変化させたりすることが可能であるため，使用温度範囲や磁場中などの外部環境に応じた設計が可能になる。