Trivalent Ion Conduction in Molybdates Having Sc₂(WO₄)₃-Type Structure

A molybdate series with Sc 2 (WO 4 ) 3 -type structure, which has been demonstrated to be suitable for trivalent ion conduction, was prepared, and the trivalent ion conducting characteristics of this series were compared with those of the tungstate series. The ionic conductivities of the molybdate series become considerably higher in comparison to those of the tungstate series. Since the ionic radius of Mo 6+ is smaller than that of W 6+, the oxide anions that form a tetrahedron unit with Mo 6+ ion form stronger bonds than those that form a tetrahedron unit with W 6+ . Stronger hexavalent cation and oxide anion bonding develops more suitable surroundings for trivalent ion migration in the Sc 2 (WO 4 ) 3 -type structure. The trivalent ion conducting properties in the molybdate solids were directly characterized by dc electrolysis and EPMA measurements.