Non-linear coefficient of BaTiO^sub 3^-doped ZnO varistor

• Published in: IET science, measurement & technology measurement & technology, 2013-11, Vol.7 (6), p.326
• Main Authors: Kharchouche, Fayçal, Belkhiat, Saâd, Belkhiat, Djamel Eddine Chouaib
• Format: Article
• Language: English
• ISSN: 1751-8822; 1751-8830

The effect of additions up to 9.6%wt BaTiO^sub 3^ on grain growth and microstructure in ZnO samples sintered at 1300 degree Celsius has been studied using scanning electron microscopy, energy dispersive X-ray, X-ray diffraction and impedance analyser as techniques. 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 BaTiO^sub 3^ leads to BaTiO^sub 3^ 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, BaTiO^sub 3^ as additive in ZnO varistors, increases the non-linear coefficient (α) and the breakdown voltage. The highest non-linearity was obtained for 9.6% wt BaTiO^sub 3^ content with α = 121.03 and 1.79 μA 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.