EFFECTS OF NB2O5 IN (BA,BI,NB)-ADDED TIO2 CERAMIC VARISTORS

Novel (Ba, Bi, Nb)-added TiO2 ceramic was previously proved to be potentially useful as a varistor material, and by varying atmosphere compensation the roles of barium and bismuth have been explored. The present work attempted to investigate how the third additive, niobium, operates on varistor characteristics. The content of added niobium is in the range from 0.125 to 1.0 cat. %, while that of the other additives is always maintained at a constant value. The results show that an adequate addition of niobium, 0.25 cat. % Nb, is beneficial to the improvement of varistor characteristics. The variations of varistor behavior are discussed in terms of a point defect model. Two kinds of charge compensation, for the substitutional incorporation of niobium into the titanium rutile lattice, are also used to illustrate the variation. The detailed results and discussions are shown in this paper.