Low temperature sintering and microwave dielectric properties of Ba3Ti5Nb6O28 with ZnO-B2O3 glass additions for LTCC applications

The effects of ZnB2O4 glass additions on the sintering temperature and microwave dielectric properties of Ba3Ti5Nb6O28 were investigated using dilatometry, XRD, SEM, XPS and network analysis. The pure Ba3Ti5Nb6O28 system showed a high sintering temperature (1250 C) and had good microwave dielectric properties: Qxf of 10600 GHz, epsilonr of 37.0, tauf of -12 ppm/C. The addition of ZnB2O4 glass to Ba3Ti5Nb6O28 lowered the sintering temperature from 1250 to 925 C. The reduced temperature was attributed to the formation of ZnB2O4 liquid phase and B2O3-rich liquid phases. The addition of ZnB2O4 glass enhanced the microwave dielectric properties: Qxf of 19100 GHz, epsilonr of 36.6, tauf of 5 ppm/C. From XPS and XRD studies, these phenomena were explained in terms of the reduction of oxygen vacancies and the formation of secondary phases with good microwave dielectric properties. 15 refs.