4 days are requested on HRPD to collect Neutron Diffraction (ND) on a carefully designed series of (Na1/2Bi1/2)TiO3-based perovskites (NBT) that exhibit a switch in electrical conduction mechanism from near band gap electronic (insulating) behaviour to high levels of oxide-ion conductivity that are comparable to the best fluorite-type solid electrolytes. This switch can be induced by low levels of Bi-nonstoichiometry in undoped NBT and the oxide ion conductivity can be enhanced by acceptor doping on the Ti sites. The purpose of the beam time is to acquire ND data from 300 to 1050 K to establish accurate crystallographic information related to the changes in polymorphism and defect chemistry of this NBT series to elucidate their structure-property relationships. This will inform future compositional studies to optimise their piezoelectric (insulating) or conducting properties.