Improved varistor nonlinearity via sintering and acceptor impurity doping
Wang, Y. J.; Wang, J. F.; Li, C. P.; Chen, H. C.; Su, W. B.; Zhong, W. L.; Zhang, P. L.; Zhao, L. Y.; Wang Y. J.; Physics Department of Shandong University, Jinan Shandong 250100, P.R. China; Wang J. F.; Physics Department of Shandong University, Jinan Shandong 250100, P.R. China; Li C. P.; Physics Department of Shandong University, Jinan Shandong 250100, P.R. China; Chen H. C.; Physics Department of Shandong University, Jinan Shandong 250100, P.R. China; Su W. B.; Physics Department of Shandong University, Jinan Shandong 250100, P.R. China; Zhong W. L.; Physics Department of Shandong University, Jinan Shandong 250100, P.R. China; Zhang P. L.; Physics Department of Shandong University, Jinan Shandong 250100, P.R. China; Zhao L. Y.; The Thunder Defense Center of Shandong, Jinan Shandong 250100, P.R. China
Журнал:
The European Physical Journal Applied Physics
Дата:
2000
Аннотация:
A new varistor system of SnO<sub>2</sub>-Bi<sub>2</sub>O<sub>3</sub>-Nb<sub>2</sub>O<sub>5</sub> was reported in this paper. The electrical field-current density characteristics of this system were investigated by doping different amounts of Bi<sub>2</sub>O<sub>3</sub> and sintering the samples at various temperatures. It is found that adding 0.75 mol% Bi<sub>2</sub>O<sub>3</sub> to Nb-doped SnO<sub>2</sub> ceramic resulted in maximum nonlinear coefficient and breakdown voltage with α = 14 and E <sub>0.5</sub> = 19 525 V/cm. To improve the density as well as the nonlinearity of this system, different amounts of Co<sub>2</sub>O<sub>3</sub> were added. The optimal conditions for the best nonlinearity were 1300 °C with 0.03 mol% Co<sub>2</sub>O<sub>3</sub> addition. Deviation from this doping content, toward either higher or lower Co<sub>2</sub>O<sub>3</sub> content, causes the deterioration of I−V characteristics. It can be concluded that the incorporation of cobalt oxides into SnO<sub>2</sub>-based varistors improves the nonlinearity in the low and intermediate current density regions because of the increased barrier height $(\Phi_{\rm B})$. The experimental results were explained with the defect barrier model for SnO<sub>2</sub>-based varistors.
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