The compositional ranges of solid solutions containing Nd, Gd, Er and Yb were determined by performing phase-diagram studies at a solidus temperature of 900C. The locus of the solid solutions indicated that the rare-earth elements replaced V in the crystal structure, to give oxide ion conductors having the general formula: Bi4+yV2-x-yMxO11-x-y. Alternating-current impedance studies showed that the Nd-, Gd-, Er- and Yb-doped materials were oxide ion conductors, but were electrically inhomogeneous. The best conductors, regardless of the type of dopant, had compositions with y = 0 and x = 0.2. The conductivities were as high as 0.0002S/cm at 300C.

Synthesis and Characterisation of Rare Earth Substituted Bismuth Vanadate Solid Electrolytes. C.K.Lee, C.S.Ong: Solid State Ionics, 1999, 117[3-4], 301-10