Characterisation of ZnO-based varistors prepared from nanometre precursor powders

Nanometre precursor powders of ZnO and various additives are synthesised by a new technology, namely chemical coprecipitation and plasma pyrolysis. Transmission electron microscopy (TEM) and the Brunauer-Emmett-Teller (BET) method are employed to illustrate the precursor powders' properties, The ZnO and additive composite powders are composed of spherical particles whose size is about 10-50 nm, Varistors are prepared by sintering the precursor powders at 1050 degrees C, Scanning electron microscopy (SEM) results show that the average grain size of the varistors is about 1.0 mu m. The prepared ZnO-based varistors have excellent electronic properties. Analytical results reveal that the breakdown voltage is 500.0 V mm(-1) and the non-linear coefficient is about 54.0. Copyright (C) 2000 John Wiley & Sons, Ltd.