The influence of dislocations on the nonlinearity of ZnO:Cu varistors

Zinc Oxide doped only with Cu shows highly nonlinear I–V characteristics. Microstructural observations of these ceramics reveal the presence of extensive dislocation network. The transmission electron microscopy (TEM) indicates that the dislocations are impurity decorated which arise as a result of limited solubility of CuO in ZnO. It is envisaged that the depletion region is generated in the region containing the dislocations because of the presence of acceptor type traps.