Epitaxial thin films of ATiO 3-xH x (A = Ba, Sr, Ca) with metallic conductivity

Epitaxial thin films of titanium perovskite oxyhydride ATiO 3-xH x (A = Ba, Sr, Ca) were prepared by CaH 2 reduction of epitaxial ATiO 3 thin films deposited on a (LaAlO 3) 0.3(SrAl 0.5Ta 0.5O 3) 0.7 substrate. Secondary ion mass spectroscopy detected a substantial amount and uniform distribution of hydride within the film. SrTiO 3/LSAT thin film hydridized at 530 °C for 1 day had hydride concentration of 4.0 × 10 21 atoms/cm 3 (i.e., SrTiO 2.75H 0.25). The electric resistivity of all the ATiO 3-xH x films exhibited metallic (positive) temperature dependence, as opposed to negative as in BaTiO 3-xH x powder, revealing that ATiO 3-xH x are intrinsically metallic, with high conductivity of 10 2-10 4 S/cm. Treatment with D 2 gas results in hydride/deuteride exchange of the films; these films should be valuable in further studies on hydride diffusion kinetics. Combined with the materials? inherent high electronic conductivity, new mixed electron/hydride ion conductors may also be possible. © 2012 American Chemical Society.