Influence of the concentration of Sb^sub 2^O3 on the electrical properties of SnO2 varistors

• Published in: Journal of materials science. Materials in electronics 2011-06, Vol.22 (6), p.679
• Main Authors: Ciórcero, J R, Pianaro, S A, Bacci, G, Zara, A J, Tebcherani, S M, Longo, E
• Format: Article
• Language: English
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-010-0195-7

Varistors are electronic materials with nonohmic behavior. In traditional SnO2 varistors, CoO acts as a densifying agent, Nb^sub 2^O^sub 5^ increases the electrical conductivity of SnO2 grains, and Cr^sub 2^O3 produces a more uniform microstructure and acts as an oxygen retaining agent at the grain boundaries. The present work involved a systematic study of the substitution of Nb^sub 2^O^sub 5^ for Sb^sub 2^O3 in the composition of a ternary varistor system. The compositions were prepared by conventional wet ceramic processing using deionized water, and the resulting slips were dried by spray-drying. Pellets were produced under a pressure of 330 MPa and sintered at 1,350 °C for 2 h. Similar to the behavior of Nb^sub 2^O^sub 5^, increasing the concentration of Sb^sub 2^O3 reduced the nonlinear behavior of the ceramic and its breakdown electric field while increasing its leakage current. The samples' microstructure showed greater porosity, suggesting that higher concentrations of Sb^sub 2^O3 reduce the sintering rate, probably in response to the higher concentration of tin vacancies in the structure.[PUBLICATION ABSTRACT]