Microwave dielectric properties and low-temperature sintering of Ba 3Ti 4Nb 4O 21 ceramics with B 2O 3 and CuO additions

Abstract

The low sintering temperature and the good dielectric properties such as high dielectric constant ( ɛ r), high quality factor ( Q × f) and small temperature coefficient of resonant frequency ( τ f) are required for the application of chip passive components in the wireless communication technologies. In the present study, the sintering behaviors and dielectric properties of Ba 3Ti 4Nb 4O 21 ceramics were investigated as a function of B 2O 3–CuO content. Ba 3Ti 4Nb 4O 21 ceramics with B 2O 3 or CuO addition could be sintered above 1100 °C. However, the additions of both B 2O 3 and CuO successfully reduced the sintering temperature of Ba 3Ti 4Nb 4O 21 ceramics from 1350 to 900 °C without detriment to the microwave dielectric properties. From the X-ray diffraction (XRD) studies, the sintering behaviors and the microwave dielectric properties of low-fired Ba 3Ti 4Nb 4O 21 ceramics were examined and discussed in the formation of the secondary phases. The Ba 3Ti 4Nb 4O 21 sample with 1 wt% B 2O 3 and 3 wt% CuO addition, sintered at 900 °C for 2 h, had the good dielectric properties: ɛ r = 65, Q × f = 16,000 GHz and τ f = 101 ppm/°C.