TRIVALENT ALUMINUM IONIC-CONDUCTION IN THE ALUMINUM TUNGSTATE SCANDIUM TUNGSTATE LUTETIUM TUNGSTATE SOLID-SOLUTION SYSTEM

The solid solutions of the Al-2(WO4)(3)-SC2(WO4)(3)-Lu-2(WO4)(3) Serie s which hold the SC2(WO4)(3)-type structure were prepared and their io nic conducting characteristics were investigated. The maximum electric al conductivity was obtained for the solid solution of (Al-2(WO4)(3))( 0.1)((Sc0.5Lu0.5)(2)(WO4)(3))(0.9) BY the measurements of the electric al conductivity dependencies on oxygen pressure and the polarization a nalyses, the mobile species in the solid solution was found to be only ionic and also oxide anion was eliminated from the candidates of the conducting ion species. Among the cation species in the solid solution , the mobile ion was demonstrated to be only Al3+ ion and the rest of the cations such as SC3+, Lu3+, and W6+ functioned as lattice-forming ions with oxide anion from the electrolysis experiments. Here, the hig hest Al3+ ion conduction was obtained in the Sc-2(WO4)(3)-type structu re and the optimal lattice size for the Al3+ ion migration in the Sc-2 (WO4)(3)-type structure was identified.