High oxide ion conduction in sintered oxides of the system Bi2O3-WO3

The ionic conduction in sintered oxides of the system Bi₂O₃-WO₃ was investigated by measuring conductivities and ion transference numbers under various conditions. The ion transference number was measured by an oxygen concentration cell employing the specimen tablet as the electrolyte.It was found that a compound 3Bi₂O₃ WO₃ and its solid solution were high oxide ion conductors, the conductivities of which were about one order of magnitude higher than those of the well-known oxide ion conductors such as stabilized zirconias. In contrast to pure Bi₂O₃ which is a completely electronic conductor below 730°C, these materials showed high oxide ion conduction even below 700°C accompanied by little electronic conduction. 3Bi₂O₃ WO₃ has the face centered cubic structure, probably of the fluorite type, and the oxide ion conduction was thought to be attributed to the migration of oxide ion vacancies in the crystal.