Ceramic system based on ZnO–CuO–glass

Abstract

Mixtures of powders containing ZnO, (CH 3COO) 2Cu·H 2O and glass frit were obtained by freeze-drying with compositions of 99 wt.% [(100 − x) mol% ZnO + x mol% Cu 2+ ( x = 0.05, 0.5, 5.0)] + 1 wt.% G, where G is a glass powder containing 26% SiO 2, 62% PbO, 7% B 2O 3, 5% ZnO in weight. Pellets were sintered in air at 950 °C/1 h. Ceramic system based on ZnO–CuO–glass originated during heating above 425 °C. Liquid-phase sintering occurred above 850 °C. Results showed that the breakdown electric field, the nonlinearity coefficient ( α), average grain size and grain boundary voltage increased; at the same time that the leakage current decreased, densification was enhanced as the Cu-contents increased from 0.05 to 5. An excess Cu-containing segregate phase was observed in ceramics containing 5.0 mol% Cu 2+. Samples presented densities above 95% of the theoretical density of ZnO and α > 200.