By considering mobile trivalent ions, and structures which were most likely to reduce the electrostatic interactions between framework and mobile trivalent ionic species, trivalent-ion conduction was successfully achieved in this tungstate structure. Among the molybdates and tungstates having the Sc2(WO4)3-type structure, Sc2(WO4)3 and Sc2(MoO4)3 were found to have the most suitable size for trivalent-ion conduction in the tungstate and molybdate series, respectively. By using direct-current electrolysis, the mobile species was demonstrated to be a trivalent ion in the Sc2(WO4)3-type structure.

Trivalent Rare Earth Ion Conduction in the Scandium Tungstate Type Structure. N.Imanaka, S.Tamura, Y.Kobayashi, Y.Okazaki, M.Hiraiwa, T.Ueda, G.Adachi: Journal of Alloys and Compounds, 2000, 303-304, 303-6