Trivalent scandium ion conduction in the scandium tungstate-alumina composites

The Al2O3 mixed with Sc-2(WO4)(3) composites were synthesized and their ion ic conducting characteristics were studied. The maximum electrical conducti vity was attained for the composite of 0.9Sc(2)(WO4)(3)-0.1Al(2)O(3). From the electrical conductivity measurements at various oxygen pressures and po larization phenomena, the mobile species in the composite was identified to be only ionic and also the oxide anion was eliminated from the candidates of conducting ion species in the composite. Among the remainders of the can didate cationic species, the mobile ion was verified to be only Sc3+ ion an d the rest of the cations W6+ and Al3+, were found to function as a lattice -forming ion with oxide anions and the insulating oxide constituent, respec tively. Here, one of the suitable techniques to enhance the ionic conductin g properties was clearly demonstrated by forming a composite with a trivale nt ion conductor and a refractory oxide insulator and the relation between the relative density of the composites and the Sc3+ ion conductivity was ex plicitly clarified. (C) 1999 Elsevier Science B.V. All rights reserved.