New bismuth ion conducting solid electrolyte

A new trivalent bismuth ion conducting solid electrolyte, (BixGe1 − x)4/(4 − x)Ta(PO4)3, was successfully developed by selecting the NASICON-type GeTa(PO4)3 as the mother solid. Although bismuth has two kinds of valence states of + 3 and + 5, it was clear that pure trivalent Bi3+ ion conduction, without any electronic conduction by a valence change of bismuth in the oxygen pressure range over 10− 3 Pa, was realized by selecting the crystal structure and constituents of the solid.