Trivalent ion conduction in molybdates having Sc-2(WO4)(3)-type structure

A molybdate series with Sc-2(WO4)(3)-type structure, which has been demonst rated to be suitable for trivalent ion conduction, was prepared, and the tr ivalent ion conducting characteristics of this series were compared with th ose of the tungstate series. The ionic conductivities of the molybdate seri es become considerably higher in comparison to those of the tungstate serie s. Since the ionic radius of Mo6+ is smaller than that of W6+, the oxide an ions that form a tetrahedron unit with Mo6+ ion form stronger bonds than th ose that form a tetrahedron unit with W6+. Stronger hexavalent cation and o xide anion bonding develops more suitable surroundings for trivalent ion mi gration in the Sca(WO4)(3)-type structure. The trivalent ion conducting pro perties in the molybdate solids were directly characterized by de electroly sis and EPMA measurements.