Low-temperature firing and microwave dielectric properties of (1−x)Ca5Mg4(VO4)6-xBa3(VO4)2 temperature stable ceramics

(1−x)Ca5Mg4(VO4)6-xBa3(VO4)2 (0.5 ≤ x ≤ 0.7) ceramics were fabricated via the conventional solid-state reaction method. The phase composition, microstructure, and compatibility with silver were investigated using X-ray diffraction, Raman spectra and Scanning electron microscopy. The results confirmed that Ca5Mg4(VO4)6 and Ba3(VO4)2 crystal phases can be well coexisted in the sintered ceramics. The temperature coefficient of resonant frequency could be tuned by the volume mixture rule of Ca5Mg4(VO4)6 and Ba3(VO4)2. As for the addition of Ba3(VO4)2, the εr showed to increase, while the Qxf declined. In particular, the 0.35Ca5Mg4(VO4)6-0.65Ba3(VO4)2 composite ceramics sintered at 900 °C for 5 h showed excellent combinational microwave dielectric properties: εr = 11.9, Qxf = 35 000 GHz, and τf = −2 ppm/°C, which also exhibited good chemical compatibility with silver.