| Summary: | 碩士 === 國立成功大學 === 資源工程學系碩博士班 === 97 === In this study, ZnO-Pr6O11-Co3O4 based varistors were prepared using a conventional solid-state reaction and sintering process. The effects of Fe2O3 addition on the microstructure and varistor properties were investigated. PrOx phases were found to locate at grain-boundaries uniformly as proper amount of Fe2O3 was added. This will promote the diffusion and chemisorptions of excess oxygen ions at the grain-boundaries, which enhances the varistor property. The energy barrier heights of the grain-boundary for the samples were measured using impedance spectroscopy and observed that when the Fe2O3 addition concentration was increased to 0.001mol%, the barrier height can be increased, which improved the varistor behavior. However, as the addition concentration of Fe2O3 was increased above 0.005mol%, most PrOx phase(s) were found to locate at the triple points, and form the second phase, ZnFe2O4, which resulted in the deterioration of the varistor property.
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