Phase composition, crystal structure and microwave dielectric properties of Mg2−xCuxSiO4 ceramics

In this work, the Mg2-xCuxSiO4(x = 0-0.40) microwave dielectric ceramics were prepared using solid-state reaction method. Compared with the Mg2SiO4 sample, the Cu-substituted Mg samples could be sintered at a lower temperature. The Mg2−xCuxSiO4 ceramics exhibit the composite phases of Mg2SiO4 and a small quantity of MgSiO3. The Cu2+ ion presented a solid solution with the Mg2SiO4 phase and preferentially occupy Mg(1) site. The distortion of MgO6 octahedron was modified by Cu2+ ions, resulting in a positive change in the temperature coefficient of resonance frequency (τf) values. Excellent microwave dielectric properties of εr = 6.35, high Qf of ∼ 188,500 GHz and near zero τf = −2.0 ppm/°C were achieved at x = 0.08 under sintering at 1250 °C for 4 h. Thus, the fabricated ceramics were considered as possible candidates for millimeter-wave device applications.