Oxide ion and proton dynamics in the novel ionic conductor Ba7Nb4MoO20

Oxide-ion and proton-conducting materials attract considerable interest thanks to their application as electrolytes in solid-oxide fuel cells (SOFCs). We have recently identified remarkable oxide ion and proton conductivity in Ba7MoNb4O20, a cation-deficient hexagonal perovskite derivative with an average crystal structure composed by palmierite-like layers alternated with hexagonal perovskite units. Ba7MoNb4O20 presents considerable local cation and anion disorder. Oxygen disorder along the palmierite-like layers leads to mixed coordination environments for Mo/Nb cations and produces pathways for ionic diffusion. Via quasielastic neutron scattering measurements as function of temperature, we aim to investigate the oxide ion and proton dynamics and gain more in-depth detail of the ionic diffusion mechanism in this fascinating novel conductor.