In situ neutron diffraction measurement on deuterization process of iron at high pressure and high temperature

Machida, Akihiko; Saito, Hiroyuki; Hattori, Takanori   ; Sano, Asami   ; Endo, Naruki*; Watanuki, Tetsu; Katayama, Yoshinori; Iizuka, Riko*; Sato, Toyoto*; Matsuo, Motoaki*; Orimo, Shinichi*; Aoki, Katsutoshi

Iron hydride FeH, is thermodynamically stable only at high hydrogen pressure of several GPa. Three hydride phases, bcc-FeH (), dhcp-FeH (), and fcc-FeH () were confirmed at 300-2000 K and 0-20 GPa. In situ neutron diffraction measurement on their deutrides have not been reported yet. A high pressure neutron diffractometor, PLANET, constructed at Materials and Life Science Experimental Facility at J-PARC, enables us to perform in situ neutoron diffraction measurements on deuterization process of metals at high pressure and high temperature. With PLANET, the deuteration process of iron was investigated at a pressure of about 7 GPa and temperatures up to about 1000 K. This in situ measurement was successfully made using a deuterization reaction cell developed for neutron diffraction measurement. We observed the bcc-fcc transition of pure iron around 800 K and successive deuterization of fcc-Fe around 870 K.