Lanthanum-containing germanate apatites are materials with potential applications as electrolytes in solid oxide fuel cells. The conductivity of these materials is known to depend greatly on the precise composition and structure (and hence on defects and the conduction pathways available). Recent computational work suggests that electronic factors are also important. We have prepared a series of materials in which La3+ is systematically partially replaced by Bi3+ (of very similar size, but an electron lone-pair containing cation). Ab-initio molecular dynamics simulations are being performed to investigate the significance of these electronic effects induced by chemical substitution, and we need to support these with direct observation of oxide ion dynamics through inelastic and quasielastic neutron scattering. For this experiment we request 4 days of beamtime on LET.