Eur. Phys. J. AP
Volume 11, Number 3, September 2000
|Page(s)||155 - 158|
|Published online||15 September 2000|
Improved varistor nonlinearity via sintering and acceptor impurity doping
Physics Department of Shandong University, Jinan Shandong 250100, P.R. China
2 The Thunder Defense Center of Shandong, Jinan Shandong 250100, P.R. China
Corresponding author: email@example.com
Revised: 19 April 2000
Accepted: 9 May 2000
Published online: 15 September 2000
A new varistor system of SnO2-Bi2O3-Nb2O5 was reported in this paper. The electrical field-current density characteristics of this system were investigated by doping different amounts of Bi2O3 and sintering the samples at various temperatures. It is found that adding 0.75 mol% Bi2O3 to Nb-doped SnO2 ceramic resulted in maximum nonlinear coefficient and breakdown voltage with α = 14 and E0.5 = 19 525 V/cm. To improve the density as well as the nonlinearity of this system, different amounts of Co2O3 were added. The optimal conditions for the best nonlinearity were 1300 °C with 0.03 mol% Co2O3 addition. Deviation from this doping content, toward either higher or lower Co2O3 content, causes the deterioration of I−V characteristics. It can be concluded that the incorporation of cobalt oxides into SnO2-based varistors improves the nonlinearity in the low and intermediate current density regions because of the increased barrier height . The experimental results were explained with the defect barrier model for SnO2-based varistors.
PACS: 72.20.Ht – High-field and nonlinear effects / 72.80.Jc – Other crystalline inorganic semiconductors
© EDP Sciences, 2000
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