Trivalent praseodymium ion conducting solid electrolyte composite with NASICON type structure

New trivalent praseodymium ion (Pr3+) conducting solid electrolyte composites, (PrxZr1-x)4/(4-x)Nb(PO4)3 (0.05≤x≤0.3)+NbPO5, were successfully developed by selecting the NASICON type structure as the mother structure candidate. The 94±5% praseodymium ion in the composites was identified to hold the trivalent state by effective magnetic moment measurements and the pure Pr3+ ion conduction in the composite solid was demonstrated both by ac conductivity measurements in various oxygen partial pressures and by dc electrolytes