CHARGE-TRANSPORT IN M3-3XLA2X(VO4)2 SOLID-SOLUTIONS WHERE M = SR OR BA

The conductivities of M3-3xLa2x(VO4)2 solid solutions where M = Sr or Ba and 0 < x < 0. 25 were measured over the temperature range from 870 to 1470 K and oxygen pressure range from 10(10) to 10(5) Pa. The part ial ionic and electronic conductivities were determined It was found t hat these compounds are ionic conductors over a wide range of temperat ures and oxygen pressures in the gas phase. Ionic transport is accompl ished by the migration of strontium and barium ions via a vacancy mech anism. The ionic conductivity in M3-3xLa2x (VO4)2 increases considerab ly with increasing concentration of the cationic vacancies. The activa tion energies of migration of the strontium and barium ions are practi cally independent of x, and have approximate values of 0.67 and 1.0 eV . The boundaries of the electrolytic regions in Sr3-3xLa2x(VO4)2 were calculated as functions of temperature.