Abstract
Effect of sintering atmosphere on maximum-energy capability of Pr-doped ZnO varistor has been studied with special reference to the microstructure. It is shown that maximum-energy capability and non-linearity are effectively improved by both introducing N2 at the heating up process of sintering and annealing at 1200°C under O2 atmosphere at cooling process. Maximum-energy capability strongly depends on the uniformity of grain size . According to the complex impedance analysis, it was found grain-boundary resistance increased and grain resistance decreased with N2-Air-O2 sintering. TEM-EDS, C-V characteristics and ICTS analysis showed that non-linearity depended on acceptor concentrations N3 which were mainly contributed by adsorbed-oxygen on Pr2O3 at grain boundaries. Interface state was calculated as 0.78eV. It was clarified by V-I characteristics of one grain boundary that grain boundary contributes varistor characteristics.
