Phase composition and microwave dielectric properties of low permittivity AGeO3 (A = Mg, Zn) ceramics

It has become a focus to develop low-permittivity microwave dielectric materials to meet the needs of high-speed transmission in telecommunication devices. Here, we report two Ge-based microwave dielectric ceramics prepared using the conventional solid-state method, MgGeO3 and ZnGeO3, with low permittivity of 6.8 and 6.6, the high-quality factor of 65,200 GHz and 25,200 GHz, and negative temperature coefficient of −45 ppm/°C and −35 ppm/°C. Orthorhombic ilmenite structure of MgGeO3 can be obtained in the range of 1160–1240 °C. However, the single-phase ZnGeO3 is not available in air, and the ceramics sintered at 1040–1120 °C contain two phases of Zn2GeO4 and GeO2.