Effect of Fe2O3 doping on the electrical properties of a SnO2 based varistor

The effect of Fe2O3 addition on the densification and electrical properties of the (0.9895 − x) SnO2 + 0.01CoO + 0.005Nb2O5 + xFe2O3 system, where x = 0.005 or 0.01, was considered in this study. The samples were sintered at 1300◦C for 2 h. Microstructure analysis by scanning electron microscopy showed that the effect of Fe2O3 addition is to decrease the SnO2 grain size. J × E curves indicated that the system exhibit a varistor behavior and the effect of Fe2O3 is to increase both, the non-linear coefficient (α) and the breakdown voltage (Er). Considering the Schottky thermionic emission model the potential height and width were estimated. Small amount addition of Fe2O3 to the basic system increases both the potential barrier height and width. C © 2002 Kluwer Academic Publishers 1