Highly Correlated Hydride Ion Tracer Diffusion in SrTiO3–xHx Oxyhydrides

Abstract

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, SrTiO3–xHx, 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 SrTiO3–xHx. More generally, the explicit description of hydride ion transport in SrTiO3–xHx through combination of experimental and computational methods reported in this work can be applied to explore anion diffusion in other mixed anion systems.