Synthesis and microwave dielectric properties of B2O3-doped Mg2GeO4 ceramics

Orthorhombic Mg2GeO4 ceramics were synthesized by solid-state reaction method. When stoichiometric compositions were employed, the phase transition produced under low temperature and pure orthorhombic Mg2GeO4 phase appeared at 1000 °C. B2O3 was employed as sintering aid to lower the sintering temperature of Mg2GeO4 ceramics and improve their relative densities. The B2O3-doped Mg2GeO4 ceramics have a low sintering temperature of 1250 °C and a small negative τf value. Microwave dielectric properties of B2O3-doped Mg2GeO4 ceramics were: εr = 6.76, Q × f = 95,000 GHz and τf = −28.7 ppm/°C. They could be considered as promising candidate materials for microwave/millimeter-wave devices.