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Report No.

In situ synchrotron $$^{57}$$Fe M$"o$ssbauer spectroscopy of RFe$$_{2}$$ (R = Y, Gd) hydrides synthesized under ultra-high-pressure hydrogen

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

An in situ $$^{57}$$Fe synchrotron radiation M$"o$ssbauer spectroscopy (SRMS) was performed on the C15 Laves RFe$$_{2}$$ (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 $$^{57}$$Fe isomer shift (IS): IS values increased for the amount of H-absorption into the RFe$$_{2}$$. 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$$_{2}$$ under high-pressure hydrogen. At the same time, two-step magnetic transitions have been also observed for the first time: ferromagnetic RFe$$_{2}$$ changed to paramagnetic RFe$$_{2}$$Hx$$_{1}$$ at the first H-absorption process, and a new ferromagnetic phase appeared in RFe$$_{2}$$Hx$$_{2}$$ at the second H-absorption process. In this conference, we report details on the SRMS experimental setup and the results.



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Category:Chemistry, Physical



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