Influence of the Sintering Temperature of Zinc Oxide Powder on the Varistor Properties of Structures Based on It

The manufacture of varistors by chemical synthesis is a promising scientific direction. Among the methods of chemical synthesis, the sol-gel method stands out especially, it has an advantage over the classical method due to a more homogenous distribution of ZnO grains and does not require high sintering temperature, moreover, unlike most chemical synthesis methods, it is much cheaper and environmentally friendly. The main purpose of this work is the synthesis of ZnO powder by the sol-gel method, followed by the manufacture of varistor structures and the study of the dependence of their parameters on the sintering temperature and operating temperature. During the work, ZnO powder was synthesized by the sol-gel method, with further fabrication of varistor structures, at sintering temperatures of 1000 °C and 1100 °C. The structure of instrumental samples was studied by scanning electron microscopy, and the current-voltage characteristics were also measured in the temperature range of 20—200 °C. The non-linearity coefficients of the current-voltage characteristic at 20 °C and the temperature coefficient of resistance were calculated. Thus, for the sample sintered at 1000 °C, the coefficient of non-linearity was 1.973 and the temperature coefficient of resistance was 0.649, and for the sample which was sintered at 1100 °C, the coefficient of non-linearity was 1.142 and the temperature coefficient of resistance was 1.0428. These results which were obtained during the work allow us to speak about an increasing in the degree of development of interfaces with the increase in the sintering temperature in turn.