Electrical conductivity of Cs3PO4 doped with trivalent cations

Cs3-3xMxPO4 (M = Sc, Y, La, Sm, Nd) solid electrolytes have been synthesized, their phase composition has been determined, and their electrical conductivity has been measured as a function of temperature. In all of the systems, we have identified cesium orthophosphate based solid solutions. Above similar to 55 degrees C, the solid solutions are isostructural with the high-temperature, cubic phase of Cs3PO4. They offer high cesium ion conductivity owing to the formation of cesium vacancies via 3Cs(+) --> M3+ substitutions and the decrease in phase transition temperature. The conductivity of the synthesized solid solutions, (4.8-5.6) x 10(-3) S/cm at 300 degrees C and (1.6-1.9) x 10(-1) S/cm at 800 degrees C, is at the level of earlier studied (Cs3-2xMxPO4)-P-II solid electrolytes.