Electrical properties of SnO2·CuO·Ta2O5 varistor system

The CuO and Ta2O5-doped SnO2 system was obtained by conventional ceramics processing. The ceramic phases of samples was analyzed by X-ray diffraction (XRD) and the microstructure by means of scanning electron microscopy (SEM). The electrical field of a single phase of CuO and Ta2O5-doped SnO2 system was studied as a function of current density behavior and compared with the CoO and Ta2O5-doped SnO2 system. A high nonlinear coefficient α=37.9 was obtained. To illustrate the grain-boundary barrier formation of CuO and Ta2O5-doped SnO2-based varistors, a modified defect barrier model is introduced.