Preparation of doped ZnO nano-powders and ZnO varistors by different methods

The powders of doped ZnO were synthesized by the solid-state reaction at a low temperature and the co-precipitation method respectively.Then the ZnO varistors were prepared at different sintering temperatures.The properties of the powders were characterized by means of XRD,SEM,TEM and BET,and the composition,microstructure of ZnO varistors were determined by XRD and SEM.The results showed that the average size of dope ZnO powders synthesized by the solid-state reaction at a low temperature was 23.95 nm,and that of doped ZnO powders by the co-precipitation method was 188 nm.The ZnO varistors prepared from the solid-state reaction powders and sintered at 1 080 ℃ had the following electric properties:potential gradient of 791.64 V/mm,nonlinear coefficient of 24.36.The ZnO varistors prepared from the co-precipitation powders and sintered at 1 130 ℃ had the following electric properties:potential gradient of 330.99 V/mm,nonlinear coefficient of 19.7.