Excited configurations of hydrogen in the BaTiOH perovskite lattice associated with hydrogen exchange and transport

BaTiOHペロブスカイト格子における水素交換および伝導に関わる水素の励起配置

伊藤 孝   ; 幸田 章宏*; 下村 浩一郎*; 髭本 亘  ; 松崎 禎市郎*; 小林 洋治*; 陰山 洋*

Ito, Takashi; Koda, Akihiro*; Shimomura, Koichiro*; Higemoto, Wataru; Matsuzaki, Teiichiro*; Kobayashi, Yoji*; Kageyama, Hiroshi*

Excited configurations of hydrogen in the oxyhydride BaTiOH (), which are considered to be involved in its hydrogen transport and exchange processes, were investigated by SR spectroscopy using muonium (Mu) as a pseudoisotope of hydrogen. Muons implanted into BaTiOH were mainly found in two metastable states. One was assigned to a highly mobile interstitial protonic state, which is commonly observed in perovskite oxides. The other was found to form an entangled two spin- system with the nuclear spin of an H ion at the anion site. The structure of the (H,Mu) complex agrees well with that of a neutralized center containing two H ions at a doubly charged oxygen vacancy, which was predicted to form in SrTiO by a computational study. Above 100 K, interstitial Mu diffusion and retrapping to a deep defect were observed, which could be a rate-limiting step of macroscopic Mu/H transport in BaTiOH.