Dielectric characteristics of the (1 - x)Mg₂TiO₄-xSrTiO₃ ceramic system at microwave frequencies

The microstructure and the microwave dielectric properties of the (1 - x)Mg₂TiO₄-xSrTiO₃ ceramic system were investigated. Mg₂TiO₄ possesses a dielectric constant (ε_r) of 14, a high quality factor (Q × f) of 150,000 GHz, and a temperature coefficient of resonant frequency (τ_f) of -50 ppm/°C. To achieve a temperature-stable material, SrTiO₃ (τ_f ∼1100 ppm/°C) was added to Mg₂TiO₄. The two-phase system was confirmed by the X-ray diffraction patterns, the EDS and the measured lattice parameters. The Q × f decreased as x increased. The ε_r, however, increased with increasing x and varied from 16.06 to 18.98 as x increased from 0.02 to 0.1. A new microwave dielectric material having an ε_r of ∼17.79, a Q × f of ∼70,900 GHz (at 10 GHz), and a τ_f of ∼-3.3 ppm/°C has been obtained from 0.94Mg₂TiO₄-0.06SrTiO₃ ceramics sintered at 1440 °C for 4 h. It is proposed as a candidate material for today's 3G applications.