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Published in:
01-06-2015
Varistor characteristics of ZnO/V2O5/MnO2/Nb2O5 semiconducting ceramics with Tb4O7 addition
Published in: Journal of Materials Science: Materials in Electronics | Issue 6/2015
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Abstract
The effect of Tb4O7 addition on the microstructure, electrical and dielectric properties, and degradation behavior of ZnO/V2O5/MnO2/Nb2O5 semiconducting ceramics was systematically investigated at a low temperature as low as 900 °C. The average grain size decreased from 5.6 to 5.2 μm until the amount of Tb4O7 is 0.05 mol%. When the amount of Tb4O7 exceeded 0.05 mol%, the average grain size increased again. The densities of the sintered pellets increased from 5.44 to 5.55 g/cm3 with increasing amount of Tb4O7. With increasing amount of Tb4O7, the breakdown field increased from 4818 to 5272 V/cm until the amount of Tb4O7 is 0.05 mol%. When the amount of Tb4O7 is 0.025 mol%, the sample exhibited the best nonohmic properties, in which the nonohmic coefficient is 65.5 and the leakage current is 72.1 μA/cm2. The donor concentration increased from 4.12 × 1017 to 7.38 × 1017 cm−3 with increasing amount of Tb4O7, and the barrier height exhibited the maximum value (1.14 eV) when the amount of Tb4O7 is 0.025 mol%.