Novel Series of Low-Firing Microwave Dielectric Ceramics: Ca5A4(VO4)6 (A2+ = Mg, Zn)

Using a conventional solid‐state reaction Ca5A4(VO4)6 (A2+ = Mg, Zn) ceramics were prepared and their microwave dielectric properties were investigated for the first time. X‐ray diffraction revealed the formation of pure‐phase ceramics with a cubic garnet structure for both samples. Two promising ceramics Ca5Zn4(VO4)6 and Ca5Mg4(VO4)6 sintered at 725°C and 800°C were found to possess good microwave dielectric properties: εr = 11.7 and 9.2, Q × f = 49 400 GHz (at 9.7 GHz) and 53 300 GHz (at 10.6 GHz), and τf = −83 and −50 ppm/°C, respectively.