Transport properties of doped BICUVOX ceramics

Polycrystalline Bi2-xLaxV0.90Cu0.10O5.5-delta (x = 0, 0.10 and 0.20) and Bi 1.90Pr0.10V0.90Cu0.10O5.5-delta were prepared by the standard ceramic-synth esis technique. The total electrical conductivity of Bi1.90La0.10V0.90Cu0.1 0O5.5-delta at temperatures above 500 K is slightly lower than undoped BICU VOX.10, but transport properties in the temperature range 370 - 450 K are s imilar. Doping BICUVOX.10 with praseodymium led to the formation of impurit y phases, and to both lower conductivity and thermal expansion of ceramic s amples. Oxygen-ion transference numbers of phases with moderate rare-earth dopant content (x less than or equal to 0.10) vary in the range 0.90 - 0.99 at 780 - 910 K and decrease with increasing temperature. Thermal expansion coefficients calculated from the dilatometric data for Bi(2-x)Ln(x)V(0.90) Cu(0.10)O(5.5-delta) ceramics are (16.1 - 18.0) x 10(-6) K-1 at 730 - 1050 K.