Preparation of ZnO-glass varistor from tetrapod ZnO nanopowders

Varistors based on ZnO–lead zinc borosilicate glass were prepared from tetrapod ZnO nanopowders, every one of which had four needle-like legs and each one was about 20 nm or less in diameter and from several hundreds of nanometers to several micrometers in length by the method of direct co-sintering synthesis of oxides instead of adding amorphous lead zinc borosilicate frit. The compact green disks were conventionally sintered in air for 2 h at a temperature of 900–1170 °C. The varistors with nonlinear coefficient α=38.7 and leakage current IL=1.7 μA were obtained. The results showed that the sintering temperature was lowered to 900 °C, and there was very little influence of the sintering temperature on the nonlinear coefficient α at a range 900–1170 °C.