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

Abstract In this paper, LaNbO 4 ceramics with BaCu(B 2 O 5 ) additives were prepared via the conventional solid state reaction method. The effects of BaCu(B 2 O 5 ) on sintering behavior, phase structure and microwave dielectric properties of LaNbO 4 ceramics were investigated. The optimum sintering temperature of LaNbO 4 ceramics could be lowered from 1325 °C to 925 °C with the addition of BaCu(B 2 O 5 ) due to liquid phase sintering. X-ray diffraction patterns showed that single-phase LaNbO 4 could be achieved when BaCu(B 2 O 5 ) content is ≤ 1 wt%. However, with further increase in BaCu(B 2 O 5 ) content, small amount of second phases such as BaNb 3.6 O 10 and Ba 6 Nb 2 O 11 would be found. The variation trends of e r and Q × f value were similar to that of bulk density, the temperature coefficient of resonant frequency ( τ f ) could be affected by additives. Typically, LaNbO 4 ceramics with 1 wt% BaCu(B 2 O 5 ) sintered at 925 °C for 4 h possessed dense structure and exhibited enhanced microwave dielectric properties: e r = 21.2, Q × f = 22600 GHz and τ f = 10.01 ppm/°C.