Both series of materials possessed a distorted 3 x 3 x 3 superstructure of the tetragonal δ-Bi2O3 polymorph. Their anion conductivities were measured at 300 to 800C. The Pb5Bi18X4O42 phases possessed higher conductivities than those of Pb5Bi17X5O43. The vanadates always had the highest conductivities; such as 1.6 x 10-2S/cm at 800C for Pb5Bi18V4O42 and 1.6 x 10-3S/cm for Pb5Bi17V5O43. An increase in the volume of the unit cell, due to an increasing radius of the pentavalent cations, P, As, V, (0.34Å, 0.47Å, 0.59Å, respectively) aided anion migration through the structure.

Structures and Ionic Conductivities in Two Fluorite Type Families - Pb5Bi17X5O43 and Pb5Bi18X4O42 (X = P, V and As). S.Giraud, S.Obbade, E.Suard, H.Steinfink, J.P.Wignacourt: Solid State Sciences, 2003, 5[2], 335-41