Nonlinear electrical properties of SnO2•Li2O•Ta2O5 varistors

The electrical properties of (Ta, Li)-doped SnO2 ceramics as a new varistor material were investigated. The sample 98.90% SnO(2)(.)1.0% Li(2)O(.)0.10% Ta2O5 (mol fraction) sintered at 1500 degreesC possesses the highest density (rho=6.63 g/cm(3)) and nonlinear electrical coefficient (alpha = 10.8). Effect of dopants and sintering temperature on the properties of the samples were investigated. The substitution of Sn4+ with Li+ and the variation of sintering temperature play very important effects on the densities, dielectric constant, nonlinear electrical properties and other characteristics of the samples. The samples sintered at 1500 degreesC exhibit better physical and electrical properties than the samples sintered at 1400 degreesC. The properties of the grain-boundary defect barriers and the microstructural characteristics were investigated to ensure the effect of the dopants and the sintering temperature. A grain-boundary defect barrier model was used to illustrate the grain boundary barrier formation in SnO2.Li2O.Ta2O5 varistors, PACS numbers: 74.40.Lq; 72.20.Ht (C) 2002 Elsevier Science Ltd and Techna S.r.l. All rights reserved.