Control of Anion Ordering in Perovskite Oxyhydrides by High-Pressure and High-Temperature Treatment.

Crystallographic order-disorder transitions are of fundamental interest due to the intimate relationship between structure and properties, while controlling anion ordering in oxide-based compounds has been less achieved. Here, we report anion-order-disorder structural control in primitive perovskite oxyhydrides. Anion-disordered vanadium perovskite oxyhydride with cubic symmetry was obtained by quenching the sample from 1000 °C to room temperature within five minutes under high pressure, while anion-ordered ones with tetragonal symmetry emerge through slow cooling from 1000 °C over 10 hours. In addition, the sign of the order-disorder structural change was also found in chromium perovskite oxyhydride. This study presents a novel synthetic route to anion-ordered oxyhydrides, enabling the future achievement of desirable properties.