Synthesis of BaCu(B2O5) Ceramics and their Effect on the Sintering Temperature and Microwave Dielectric Properties of Ba(Zn1/3Nb2/3)O3Ceramics

BaCu(B2O5) ceramics were synthesized and their microwave dielectric properties were investigated. BaCu(B2O5) phase was formed at 700°C and melted above 850°C. The BaCu(B2O5) ceramic sintered at 810°C had a dielectric constant (ɛr) of 7.4, a quality factor (Q×f) of 50 000 GHz and a temperature coefficient of resonance frequency (τf) of −32 ppm/°C. As the BaCu(B2O5) ceramic had a low melting temperature and good microwave dielectric properties, it can be used as a low-temperature sintering aid for microwave dielectric materials for low temperature co-fired ceramic application. When BaCu(B2O5) was added to the Ba(Zn1/3Nb2/3)O3 (BZN) ceramic, BZN ceramics were well sintered even at 850°C. BaCu(B2O5) existed as a liquid phase during the sintering and assisted the densification of the BZN ceramic. Good microwave dielectric properties of Q×f=16 000 GHz, ɛr=35, and τf=22.1 ppm/°C were obtained for the BZN+6.0 mol% BaCu(B2O5) ceramic sintered at 875°C for 2 h.