Phase compositions and microwave dielectric characteristics of xMg2B2O5-(1-x)Ba3V2O8 (0.5 ≤x ≤ 0.7) ceramics

Herein, xMg2B2O5-(1-x)Ba3V2O8 (0.5 <= x <= 0.7) microwave dielectric composite ceramics were prepared via the solid-state reaction method at a relatively low sintering temperature (around 940-1020 degrees C). The phase compositions, microstructure, and elemental compositions of the ceramics were characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM) combined with energy-dispersive spectroscopy (EDS), respectively. According to the results, both Mg2B2O5 and Ba3V2O8 phases coexisted after sintering in the temperature range of 940-1020 degrees C. The growth of Ba3V2O8 grains was inhibited by the increase in amount of Mg2B2O5 inclusions. Moreover, mixing these two phases in a proper ratio did not only reduce the sintering temperature, but also improved the temperature coefficient of resonant frequency (Tau f) and Qxf value (Q is quality factor=1/ dielectric loss, f=resonant frequency) of the xMg2B2O5-(1-x)Ba3V2O8 microwave dielectric ceramics. In particular, the optimal microwave dielectric properties (epsilon r = 10.1, Qxf = 48,050 GHz, Tau f = -3 ppm/degrees C) were reached after 2 h of sintering at 960 degrees C for the ceramic with x = 0.7.(c) 2022 Elsevier B.V. All rights reserved.