Abstract A varistor having ultra-high performance was developed from doped ZnO nanopowders using a novel composition consisting of only three (Bi, Ca and Co oxides) dopants. Improved varistor properties were… Click to show full abstract
Abstract A varistor having ultra-high performance was developed from doped ZnO nanopowders using a novel composition consisting of only three (Bi, Ca and Co oxides) dopants. Improved varistor properties were obtained (breakdown field (Eb) 27.5 ± 5 kVcm−1, coefficient of nonlinearity (α) 72 ± 3 and leakage current density (Lc) 1.5 ± 0.06 μAcm−2) which are attributed to the small grain size and grain boundary engineering by phases such as Ca4Bi6O13 and Ca0.89Bi3.11O5.56 along with Co+2 doping in the ZnO lattice. Complex impedance data indicated three relaxations at 25 °C and two relaxations at high temperature (>100 °C). The complex impedance data were fitted into two parallel RC model to extract electrical properties. Two stages of activation energy for DC conductivity were observed in these varistor samples where region I (
Journal Title: Journal of the European Ceramic Society
Year Published: 2018
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