A single crystal of Bi1.94Pb0.06V0.9Co0.1O5.32, in which the Bi- and V-sites of layer-structured Bi2VO5.5 had been substituted simultaneously, was prepared for the first time. No improvement in ionic conductivity along the c-axis perpendicular to the (Bi2O2)2+ layer was observed, as compared with single crystals without Pb substitution. The conductivity results, and Rietveld refinement of the X-ray diffraction patterns, suggested that O vacancies which were generated by Pb substitution were located in the pseudo-perovskite block, rather than in the (Bi2O2)2+ layer.

Ionic Conductivity of Pb- and Co-Substituted Bi2VO5.5 Single Crystals. N.Yasuda, M.Miyayama, T.Kudo: Journal of the American Ceramic Society, 2001, 109[4], 285-7