Conductivity of Al2(WO4)3-WO3 and Al2(WO4)3-Al2O3 Composites

Composites of (1 - x)Al-2(WO4)(3)-xWO(3) and (1 - x)Al-2(WO4)(3)-xAl(2)O(3) are synthesized and their conductivity is studied as dependent on the temperature and oxygen pressure in the gas phase. The transport numbers of charge carriers are determined using the EMF and Tubandt methods. It is shown that there is a composite effect in the Al-2(WO4)(3)-Al2O3 system: when 20-60 mol % of nanodispersed Al2O3 is added to Al-2(WO4)(3), ionic conductivity of the composites increases by 0.5-0.8 orders of magnitude as compared to Al-2(WO4)(3). The dependence of conductivity of the (1 - x)Al-2(WO4)(3)-xAl(2)O(3) composites on the Al2O3 content passes through a maximum. Such an effect is typical for composite solid electrolytes and can be explained by an additional contribution of interfaces, where the complex oxide is more disordered. There is no composite effect in the Al-2(WO4)(3)-WO3 system. When Al-2(WO4)(3) and WO3 are mixed, a statistical composite is formed with its conductivity determined by the conductivity of the main phase.