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

Novel (Ba, Bi, Nb)-added TiO2 ceramic was previously proved to be pote ntially useful as a varistor material, and by varying atmosphere compe nsation the roles of barium and bismuth have been explored. The presen t work attempted to investigate how the third additive, niobium, opera tes on varistor characteristics. The content of added niobium is in th e 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 adequ ate addition of niobium, 0.25 cat. % Nb, is beneficial to the improvem ent of varistor characteristics. The variations of varistor behavior a re discussed in terms of a point defect model. Two kinds of charge com pensation, for the substitutional incorporation of niobium into the ti tanium rutile lattice, are also used to illustrate the variation. The detailed results and discussions are shown in this paper.