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Varistors in the new system ZnO--Bi203--SiO2 were prepared through conventional ceramic processing route. The effect of sintering temperature and time (0.5 h to 2 h between 1000 ° and 1250°C) on the microstructure and current/voltage characteristics of the varistors of the new system were investigated and the results were compared with those of ZnO-Bi203 system varistors prepared. An increase in nonlinear coefficient (a) value was observed in the Sit 2 added varistors. The microstructure and the phase of the varistors were examined by means of SEM and XRD. The Zn2SiO 4 spinel phase was found to be present in the inteegranular region. The grain growth exponent was determined to be 2-5 +0-2 and the activation energy for the ZnO grain growth was estimated to be 251 +11 kJ/mol. These values were compared with those estimated for ZnO--Bi203 system varistors.

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