Effect of CeO2 on the sintering behaviour, cation order and properties of Ba3Co0.7Zn0.3Nb2O9 ceramics

The effect of low-level CeO2 addition and cooling rate on sintering, microstructures, phase formation, 1:2 ordering and microwave dielectric properties of Ba3Co0.7Zn0.3Nb9 (BCZN) was investigated. It was found that low levels doping of CeO2 (up to 0.5 wt.%) could significantly improve densification of the specimens and their properties. Dielectric properties of CeO2-doped samples were sensitive to 1:2 ordering in the B-site. Slow cooling after sintering improved the unloaded quality factor (Q × f values) significantly. The B-site ordering parameter (S) and lattice constant (c/a) values increased as the cooling rate decreased. Ba5Nb4O15 (5/0/4) and Ba8(Co,Zn)1Nb6O24 (8/1/6) secondary phases were found on the surface of all the samples. At 0.4 wt.% CeO2 the specimens showed maximum Q × f of 84,000 GHz attributed to high density and the degree of cation ordering.