Influence of CuO and B2O3 on sintering and dielectric properties of tungsten bronze type microwave ceramics: a case study in Ba_4Nd_(9.3)Ti_(18)O_(54)

摘要

The effect of CuO and B_2O_3 co-doping on the sintering behavior, microstructure and microwave dielectric properties of tungsten bronze type Ba_4Nd_(9.3)Ti_(18)O_(54) (BNT) ceramics has been investigated by means of a traditional solid-state mixed oxide route. On the one hand, it was indicated that the mixture of CuO and B_2O_3 is an effective sintering aid for BNT matrix compositions owing to the existence of a low-temperature eutectic reaction. On the other hand, it was found that the addition of CuO and B_2O_3 has an obvious effect on microwave dielectric properties of BNT ceramics, depending on the amount of sintering aids, the sample density and microstructure. The liquid phases from sintering aids can promote densification, but simultaneously induce grain growth which tends to decrease the sintering driving force. BNT ceramics doped with 3 wt% CuO-B_2O_3 mixture can be well sintered at 950℃ for 4 h and still exhibit relatively good microwave dielectric properties.