Quasielastic neutron scattering probing H
dynamics in the H
conductors LaH
O
ヒドリド(H
)伝導体LaH
O
におけるH
ダイナミクスの中性子準弾性散乱法による探査
玉造 博夢
; 福井 慧賀*; 飯村 壮史*; 本田 孝志*; 多田 朋史*; 村上 洋一*; 山浦 淳一*; 倉本 義夫*; 佐賀山 基*; 山田 武*; 松浦 直人*; 柴田 薫
; 古府 麻衣子
; 川北 至信
; 池田 一貴*; 大友 季哉; 細野 秀雄*
Tamatsukuri, Hiromu; Fukui, Keiga*; Iimura, Soshi*; Honda, Takashi*; Tada, Tomofumi*; Murakami, Yoichi*; Yamaura, Junichi*; Kuramoto, Yoshio*; Sagayama, Hajime*; Yamada, Takeshi*; Matsuura, Masato*; Shibata, Kaoru; Kofu, Maiko; Kawakita, Yukinobu; Ikeda, Kazutaka*; Otomo, Toshiya; Hosono, Hideo*
Using an incoherent quasi-elastic neutron scattering (QENS) technique, we investigate H
dynamics in a series of oxyhydrides LaH
O
that exhibit characteristic high H
conductivity. In the end member LaH
(
= 0), two kinds of H
dynamics are identified: the jump diffusion and the localized motion. The jump length in the jump diffusion mode increases with increasing
. The localized motion is identified as a jump between the two inequivalent sites. These dynamics are corroborated by our molecular dynamical simulations. Our QENS data suggest that similar H
dynamics occurs also in oxyhydrides LaH
O
(
0), whose H
concentration dependence is consistent with the previous measurement of ionic conductivity. We also discuss the possibility that LaH
O
is an example of H
ion conductors governed by the concerted migration mechanism. The identified H
dynamics is a key to understanding the anomalous hydrogen concentration dependence of the diffusion coefficient in lanthanum hydrides, which has been a longstanding mystery in this compound.