Oxyhydrides of (Ca,Sr,Ba)TiO3 perovskite solid solutions.

The oxyhydride solid solutions (Ca,Sr)TiO(3-x)H(x) and (Sr,Ba)TiO(3-x)H(x) have been prepared by reducing the corresponding ATiO(3) oxides with calcium hydride. Under the reaction conditions examined, a hydride content of x = 0.1-0.3 was obtained for all compositions. Compared to our previous result with BaTiO(3-x)H(x), the larger particle size in this study (20-30 μm vs 170 nm) resulted in a somewhat lower hydride amount despite prolonged reaction times. We examined changes in cell volume, octahedral tilt angle, and site occupancy of different anion sites after conversion to oxyhydrides; it appears that these oxyhydrides fit the geometrical descriptions typical for regular ABO(3) perovskites quite well. The hydrogen release temperature, previously shown to be indicative of the hydride exchange temperature, however, does not scale linearly with the A-site composition, indicating a potential effect of chemical randomness.