Effect of CeO2 on the microstructure and electrical properties of WO3 capacitor-varistor ceramics

WO3 (Tungsten trioxide)-based varistors doped with CeO2 were prepared and the microstructures, non-linear electrical properties, dielectric properties were investigated. All the doped samples revealed existence of monoclinic WO3 phase without triclinic WO3, resulting in stable electrical properties under a high electric field. Moreover, the electrical properties under a low electrical field are also stable because ion migration in the depletion layer is ignorable. The non-linear coefficient was not high, but the barrier voltage was extremely low with the value of about 0.04 V for the sample containing 2 mol% CeO2. The permittivity of doped samples was higher than that of undoped samples, which could be attributed to the decrease in thickness of grain-boundary. CeO2-doped WO3 ceramic is a new kind of low voltage capacitor-varistor material. (C) 2004 Elsevier B.V. All rights reserved.