Crystal structure and microwave dielectric properties of middle-temperature-sintered Mg₂Si_(1-x)V _x O₄ ceramics

Mg₂Si_(1-x)V _x O₄ (0.0 ≤ x ≤ 0.3) ceramics were fabricated via a conventional solid state reaction route, and their densification behaviors, structure and microwave dielectric properties were investigated systematically. A single phase Mg₂SiO₄ was obtained for the samples with x ≤ 0.05, and the lattice constant increased with increasing V content due to the larger ionic radius of V⁵⁺ than that of Si⁴⁺. Moreover, the density and microwave dielectric property strongly depended on the substitution content of V⁵⁺ and sintering temperature. Typical, Mg₂Si_0.8V_0.2O₄ ceramic obtained a maximum density of 3.24 g/cm³ and exhibited good microwave dielectric properties of ε _r  = 8.8, Q × f = 79900 GHz, and τ _f  = −57.5 ppm/°C at 1180 °C.