Effects of barium on the nonlinear electrical characteristics and dielectric properties of SnO2-based varistors

摘要

The effects of barium on electrical and dielectric properties of the Sno(2).Co2O3.Ta2O5 varistor system sintered at 1250degreesC for 60min were investigated. It is found that barium significantly improves the nonlinear properties. The breakdown electrical field increases from 378.0 to 2834.5V/mm, relative dielectric constant (at 1kHz) falls from 1206 to 161 and the resistivity (at 1kHz) rises from 60.3 to 1146.5kOmega.cm with an increase of BaCO3 concentration from 0mol% to 1.00mol%. The sample with 1.00mol% barium has the best nonlinear electrical property and the highest nonlinear coefficient (alpha=29.2). A modified defect barrier model is introduced to illustrate the grain-boundary barrier formation of barium-doped SnO2-based varistors.