Low temperature sintering behavior and microwave dielectric properties of LaNbO4 ceramics with BaCu(B2O5) additive

In this paper, LaNbO4 ceramics with BaCu(B2O5) additives were prepared via the conventional solid state reaction method. The effects of BaCu(B2O5) on sintering behavior, phase structure and microwave dielectric properties of LaNbO4 ceramics were investigated. The optimum sintering temperature of LaNbO4 ceramics could be lowered from 1325 °C to 925 °C with the addition of BaCu(B2O5) due to liquid phase sintering. X-ray diffraction patterns showed that single-phase LaNbO4 could be achieved when BaCu(B2O5) content is ≤ 1 wt%. However, with further increase in BaCu(B2O5) content, small amount of second phases such as BaNb3.6O10 and Ba6Nb2O11 would be found. The variation trends of εr and Q×f value were similar to that of bulk density, the temperature coefficient of resonant frequency (τf) could be affected by additives. Typically, LaNbO4 ceramics with 1 wt% BaCu(B2O5) sintered at 925 °C for 4 h possessed dense structure and exhibited enhanced microwave dielectric properties: εr = 21.2, Q×f = 22600 GHz and τf = 10.01 ppm/°C.