Improved microwave dielectric properties of Mg4Nb2O9 ceramics with CaO–B2O3–SiO2 glass additions

The effects of CaO–B2O3–SiO2 (CBS) glass addition on the sintering temperature and dielectric properties of Mg4Nb2O9 ceramics have been investigated using X-ray diffraction, Scanning electron microscopy and Differential thermal analysis. The CBS glass can change to liquid phase at about 750 °C and a small amount of CBS glass addition to Mg4Nb2O9 ceramics can greatly decrease the sintering temperature to about 1,125 °C. It is revealed that the reduced sintering temperature is attributed to the formation of liquid phase. The major phases of the sample are Mg4Nb2O9 and MgNb2O6. The relationship between τf values and the content of glass additions have the reverse change trends. The Mg4Nb2O9 ceramics with 2wt% glass addition sintered 1,125 °C exhibit good microwave dielectric properties: dielectric constant (εr) of 13 and Q·f value of 69,000 GHz.