Characterising oxygen diffusion in scheelites La(Nb,Mo)O4+δ

Oxide ion conductors are key components in several technologically important applications, including solid oxide fuel cell (SOFC) devices to allow the safe conversion of hydrogen fuel into energy. The scheelite material LaNbO4 exhibits moderate oxide ion conductivity that is greatly enhanced by the partial replacement of niobium with molybdenum (up to 20%); this also introduces excess interstitial oxide ions into the crystal lattice. The aim of this proposal is to shed light on the atomic-scale processes involved in oxide ion conductivity in scheelites, as well the effects of increasing Mo (and interstitial oxide) content on this behaviour. Quasielastic neutron scattering measurements of La(Nb,Mo)O4+d samples containing 0%, 8% and 20% Mo will allow us to determine the rate and activation energy of oxygen motions at high temperatures, which we will relate to their structure and chemistry.