Faceting at ZnO-Bi2O3 Interphase Boundaries in ZnO-based Varistor Ceramics

ZnO-based varistor ceramics containing Bi₂O₃, Sb₂O₃, MnO and Co₃O₄ obtained by water quenching from the sintering temperature of 1250 °C show extensive faceting at ZnO - δ-Bi₂O₃ interfaces. Trace analysis showed that facets are the ZnO basal plane, ZnO prism planes or low index pyramidal planes. The most prominent facets were generally found to be the ZnO prism planes which are populated by equal proportions of zinc and oxygen atoms and are thus relatively favoured low energy planes.