Electronic state of trivalent ionic conductors with Sc-2(WO4)(3)-type structure

The electronic state of M-2(WO4)(3) trivalent ion conductors (M = Al, Sc, L u, Yb, Tm, Er, Y) was calculated by the discrete-variational X alpha molecu lar orbital (DV-X alpha MO) method. The bond overlap populations between th e M3+ ion and the surrounding oxide ions and the net charge of M3+, W6+, an d O2- ions were compared with the experimental ionic conductivity of M-2(WO 4)(3) crystals. The variation of the activation energy of ionic conductivit y agreed qualitatively with the change of the bond overlap population betwe en the migrating trivalent ion and the surrounding oxide ions. This result suggests that the bonding state of the trivalent ions plays an important ro le in trivalent ion conduction in M-2(WO4)(3) crystals. (C) 2000 Elsevier S cience B.V. All rights reserved.