Trivalent ion conduction in solids was obtained in a Sc2(WO4)3-type structure by adjusting the stability and size of mobile trivalent ions and of the structure so as to reduce the electrostatic interaction between the framework and the mobile ionic species. Among tungstates and molybdates having the Sc2(WO4)3-type structure, Sc2(MoO4)3 and Sc2(WO4)3 were found to have the most suitable lattice size for trivalent-ion migration. By means of direct-current electrolysis and electron-probe micro-analysis, measurements, the mobile species in the Sc2(WO4)3-type structure were clearly identified as being trivalent ions.

Trivalent Ion Conducting Solid Electrolytes. N.Imanaka, Y.Kobayashi, S.Tamura, G.Adachi: Solid State Ionics, 2000, 136-137, 319-24