The sintering time influence on the electrical and microstructural characteristics of SnO2 varistor

The variation of the electrical properties of a well-known tin oxide varistor composition in relation to the sintering time for temperatures of 1300 and 1350 °C was studied in this work. It was verified that the barrier voltage value, vb, varies according to the varistor sintering time. Stable electrical barriers between 2.0 and 2.4 V/barrier produce varistors with non-linear coefficients higher than 35, independently of the sintering temperature. The variation of the grain size in relation to the sintering time was 45.1% for sintering at 1300 °C and 33.6% for sintering at 1350 °C, considering the minimum time of 1 h and the maximum of 12 h, with considerable variations in the respective electrical breakdown fields. Therefore, the sintering time is a very important variable which should not be despised in the project of tin oxide varistor production.