Highly Correlated Hydride Ion Tracer Diffusion in SrTiO_{3- x}H _x Oxyhydrides

Mixed oxide hydride anion systems constitute a novel class of materials exhibiting intriguing properties such as solid-state hydride ion conduction and fast anion exchange. In this contribution we derive the kinetics of hydride ion transport in a mixed oxide-hydride system, SrTiO_{3- x}H _x, through isotope exchange and depth profiling. Density functional theory (DFT) calculations indicate that migration of H^- to neighboring vacant oxygen lattice sites is fast, but that long-range transport is impeded by slow reorganization of the oxygen sublattice. From measured hydride tracer-diffusion coefficients and the correlation factors derived from DFT, we are able to derive the hydrogen self-diffusion coefficients in SrTiO_{3- x}H _x. More generally, the explicit description of hydride ion transport in SrTiO_{3- x}H _x through combination of experimental and computational methods reported in this work can be applied to explore anion diffusion in other mixed anion systems.