Non-linear coefficient of BaTiOINF3INF-doped ZnO varistor

The effect of additions up to 9.6%wt BaTiOINF3INF on grain growth and microstructure in ZnO samples sintered at 1300 degrees C has been studied using scanning electron microscopy, energy dispersive X-ray, X-ray diffraction and impedance analyser as techniques. The sample doped with 1.6%wt BaTiOINF3INF, leads to grain size increasing and forms (BaOINF10.89INFTiINF3.93INFZnINF2.03INF and BaINF4INFOINF27INFTiINF11INF Zn) solid solutions with ZnO. A homogeneous structure was obtained whereas with further additions 3%wt the structure was inhomogeneous and the solid solutions formed in the first segregate to grain boundaries. Afterwards, an excess of 9.6%wt BaTiOINF3INF leads to BaTiOINF3INF phase segregation locating on the surface of the sample and in the grain boundaries near the junctions between matrix grains. Experimental I-V current-voltage characteristics show that BaTiOINF3INF as additive in ZnO varistors, increases the non-linear coefficient () and the breakdown voltage. The highest non-linearity was obtained for 9.6%wt BaTiOINF3INF content with = 121.03 and 1.79 mu A in leakage current. The average breakdown voltage per grain boundary (Vgb) was evaluated in the ranges 1.7-3.46 V/gb and 1.34-2.54 V/gb in agreement with the literature.