Low-voltage ZnO varistor fabricated by the solution-coating method

A novel solution nano-coating technique, by coating ZnO powder with a mixed solution of dopants, has been developed to produce high performance low-voltage ZnO varistors. The sintering temperature in the present route is about 50 °C lower than that in the conventional oxide mixing route. The microstructure and electrical characteristics were examined by XRD, SEM and dc power supply and the results showed that the specimens prepared by the solution-coating route have bigger grain sizes, more evenly distributed intergranular phases, higher densities and nonlinearity coefficients, lower breakdown fields and leakage currents than those from the conventional oxide mixing route. The improved current–voltage properties are attributed to the excellent performance of the nano-composite ZnO powder and the advantages of the solution nano-coating technique.