In situ synchrotron Fe Mssbauer spectroscopy of RFe (R = Y, Gd) hydrides synthesized under ultra-high-pressure hydrogen

高圧水素下RFe合金の放射光メスバウアー分光

三井 隆也; 増田 亮*; 瀬戸 誠; 平尾 直久*; 松岡 岳洋*; 中村 優美子*; 榊 浩司*; 榎 浩利*

Mitsui, Takaya; Masuda, Ryo*; Seto, Makoto; Hirao, Naohisa*; Matsuoka, Takehiro*; Nakamura, Yumiko*; Sakaki, Koji*; Enoki, Hirotoshi*

An in situ Fe synchrotron radiation Mssbauer spectroscopy (SRMS) was performed on the C15 Laves RFe (R=Y, Gd) under high-pressure hydrogen (H) in a diamond anvil cell. The H-absorption processes were monitored by the pressure dependence on the Fe isomer shift (IS): IS values increased for the amount of H-absorption into the RFe. In both cases, IS values showed a rapid increase at a few GPa, and once again showed a small increase at above 10 GPa. These results suggest that there are two steps in the H-absorption processes for the RFe under high-pressure hydrogen. At the same time, two-step magnetic transitions have been also observed for the first time: ferromagnetic RFe changed to paramagnetic RFeHx at the first H-absorption process, and a new ferromagnetic phase appeared in RFeHx at the second H-absorption process. In this conference, we report details on the SRMS experimental setup and the results.