Grain Size Effects of SnO2 Varistor Induced by Doping Pr
The effects of Pr on the microstructure and nonlinear electrical properties of the (Co,Ta)-doped SnO2 varistors were investigated. It was found by characterizing the samples sintered at 1350 oC that the breakdown voltage increases significantly from 500v/mm to 1200v/mm, and the relative permittivity decreased rapidly from 2525 to 1199 with increasing Pr6O11 concentration from 0 to 1.20 mol%. The analysis of samples’ microscopic structure showed that the grain size of SnO2 rapidly decreases from 5.1 to 3.7 µm with increasing Pr6O11 concentration from 0 to 1.20mol% .The significant decrease of SnO2 grain size is the main reason for raising breakdown voltage and reducing permittivity.
Wei Pan, Jianghong Gong, Chang-Chun Ge and Jing-Feng Li
C. J. Zhang et al., "Grain Size Effects of SnO2 Varistor Induced by Doping Pr", Key Engineering Materials, Vols. 280-283, pp. 275-278, 2005