Electrical properties of epitaxial thin films of oxyhydrides ATiO3-xHx (A = Ba and Sr)

Year: 2015 DOI: 10.1021/acs.chemmater.5b02374

Extra Information

Guillaume Bouilly, Takeshi Yajima, Takahiro Terashima, Wataru Yoshimune, Kousuke Nakano, Cédric Tassel, Yoshiro Kususe, Koji Fujita, Katsuhisa Tanaka, Takafumi Yamamoto, Hiroshi Kageyama.   Chemistry of Materials, 2015, 27, 6354-6359.


We have studied electronic properties of perovskite oxyhydrides ATiO3–xHx (A = Ba, Sr). Epitaxial thin films of ATiO3–xHx with various hydride compositions, up to x = 0.58 for Ba and x = 0.45 for Sr, are prepared by the low-temperature CaH2 reduction of the corresponding oxide films deposited on (LaAlO3)0.3(SrAl0.5Ta0.5O3)0.7 (LSAT) substrates by pulsed laser deposition. Resistivity measurements for A = Sr show a metallic phase over a wide range of H composition, implying a substantial stabilization of H 1s orbitals that should be distributed over O 2p orbitals. On the other hand, for A = Ba, a semiconducting behavior is seen up to ∼5–8% of H– substitution. Interestingly, a similar contrasting behavior is observed in a Nb-substituted BaTiO3 and SrTiO3, which suggests that a local cation–off centering in lightly doped Ba films creates in-gap states in the band structure (as opposed to the Sr films), hindering the electron transport.