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 have been investigated using dilatometer, X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and a network analyzer. The pure Ba3Ti5Nb6O28 system showed a high sintering temperature (1250 °C) and had the good microwave dielectric properties: Q × f of 10,600 GHz, ɛr of 37.0, τf of −12 ppm/°C. It was found that the addition of ZnB2O4 glass to Ba3Ti5Nb6O28 lowered the sintering temperature from 1250 to 925 °C. The reduced sintering temperature was attributed to the formation of ZnB2O4 liquid phase and B2O3-rich liquid phases. Also the addition of ZnB2O4 glass enhanced the microwave dielectric properties: Q × f of 19,100 GHz, ɛr of 36.6, τf 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 having the good microwave dielectric properties.