Improved high-Q microwave dielectric material using B2O3-doped MgNb2O6 ceramics

In this paper, the microstructures and microwave dielectric properties of MgNb2O6 ceramics doped with B2O3 are investigated. The formation of an impurity phase is not detected by X-ray diffraction pattern and the grain growth is apparent with increasing the sintering temperature from scanning electron microscopy results. With adding the sintering aid B2O3, not only decreasing the sintering temperature but also enhancing the quality factor (Q) value are obtained. The maximum Q × f value obtained in this study is 115,800(GHz) with 0.25 wt.% B2O3 added sintered at 1260 °C that possesses a dielectric constant (ɛr) of 21.5 and the temperature coefficients of resonant frequency (τf) of −48 ppm/°C. The correlation between dielectric properties and the microstructures with different doped amounts of B2O3 is also discussed.