Abstract
Formation of faults in ZnO grain by addition of some metal oxides were studied. Two kinds of faults were observed in non-ohmic polycrystalline ZnO (ZnO varistor): one is twin-type and the other is stacking-type. ZnO grains having twin structures were obsereved with specimens prepared by adding small amount of Sb2O3 (75ppm), Sc2O3 (75ppm) and SnO2 (25ppm). The stacking structure in ZnO seemed change with the amount of additions. The formation mechanism of twinned structure obtained by addition of SnO2 was unknown to date.
