Abstract
We report the structural and nonlinear behavior of Sn1-x-yZnxMyOz varistors with x = 0.00, 0.50, y = 0.00, 0.25 and M = Fe, Co, Ni and Mn. The crystallite and grain sizes and porosity of SnO2 are decreased by Zn doping, followed by a further decrease by (Zn + M) co-substitution. The breakdown field (E-B), nonlinear coefficient (alpha), leakage current (I-K) and residual voltage (K-r) of SnO2 are respectively 333.35 V/cm, 5.6, 900 mu A/cm(2) and 5.32. When SnO2 was substituted by Zn, I-K and K-r are decreased to 816 mu A/cm(2) and 3.62, whereas E-B and alpha are increased to 666.67 and 11.48. The E-B and alpha values are increased by co-substitution in the SnZnMn sample, whereas I-K and K-r are decreased. Rather than containing many elements and compounds, the current varistors are based on only two well-known ions co-substituted into SnO2. These findings are discussed in terms of the oxygen vacancies.