材料期刊网

We have studied the densification behaviour, microstructure and electrical properties of WO3 ceramics with V2O5 as the additive ranging from 0.5 to 15mol%. Scanning electron microscopic photos indicated that the grain size of WO3-V2O5 specimens is smaller than that of pure WO3. The addition of V2O5 to WO3 showed a tendency to enhance the densification rate and to restrict the grain growth. Electrical properties of all specimens were measured for different electrodes at different temperatures. The formation of the grain boundary barrier layer was confirmed by the non-ohmic I-V behaviour. The nonlinear coefficient was obtained at the current density J=0.01, 0.1 and 1mA/cm(2) for a series of WO3-V2O5 samples. The V0.5mol% specimen showed an abnormal phenomenon that the nonlinear characteristics appeared at 350degreesC and disappeared at lower and higher temperatures. This implies that it could be applied as a high-temperature varistor. The double Schottky barrier model was adopted to explain the phenomena for the WO3-V(2)o(5) varistors.