Fluorite-type fcc phases were synthesised in the system Bi2O3–Er2O3–PbO by solid state reaction, and a partial air-quenchable domain of the fluorite-type phase was established. Some of these materials display high oxide ion conductivities, notably (BiO1.5)0.80(ErO1.5)0.11(PbO)0.09 and (BiO1.5)0.85(ErO1.5)0.12(PbO)0.03, which have conductivities of 0.49 and 0.72S/cm at 750C, respectively, placing them among the most conductive Bi2O3-based materials. Conductivity was found to increase with increasing Pb2+/Er3+ ratio and decreasing (Er3++Pb2+)/Bi3+ ratio. Positional disorder in the oxide ion sub-lattice was characterised by neutron powder diffraction. At room temperature, the oxide ion sub-lattice appeared to be completely disordered, with oxide ions only in 32f and 48i sites, and changes in occupancy with increasing Pb2+/Er3+ and (Er3++Pb2+)/Bi3+ ratios were not significant. At 700C, there appeared to be oxide ions in 8c sites for the material (BiO1.5)0.80(ErO1.5)0.11(PbO)0.09, with a correspondingly smaller occupancy of the 32f sites, whilst the occupancy of the 48i sites had not changed significantly.

The Structure and Conductivity of New Fluorite-Type Bi2O3–Er2O3–PbO Materials. N.A.S.Webster, C.D.Ling, C.L.Raston, F.J.Lincoln: Solid State Ionics, 2007, 178[25-26], 1451-7