Low loss and temperature stable microwave dielectric ceramics in (1 − x)Li₂TiO₃–xLi₂Mg₃TiO₆ (0.1 ≤ x ≤ 0.5) system

The (1 − x)Li₂TiO₃–xLi₂Mg₃TiO₆ (x = 0.1, 0.15, 0.2, 0.3, 0.4, 0.5) ceramics system was fabricated by solid-state synthesis. Test results of X-ray diffraction and electron diffraction spectrum show that all ceramic samples only contain Li₂TO₃ and Li₂Mg₃TiO₆ phase. Scanning electron microscope shows that pores were found in crystal grain due to Li volatilization in high temperature (> 1000 °C). With the rise proportion of Li₂Mg₃TiO₆ in ceramics, dielectric constant (ɛ_r) decreases from 19.55 to 14.53, quality factor (Q×f) increases from 102,800 to 126,000 GHz and temperature coefficient (τ_f) decreases from + 15.9 to − 30.08 ppm/°C. High performance microwave dielectric properties of ɛ_r = 18.5, Q×f = 108,000 GHz, τ_f = 4.2 ppm/°C were obtained at 1390 °C for 0.85Li₂TiO₃–0.15Li₂Mg₃TiO₆ ceramics. To suppress Li volatilization, LiF, a low temperature melting addition, was added to 0.85Li₂TiO₃–0.15Li₂Mg₃TiO₆ ceramics. LiF effective lowers sintering temperature from 1390 to 1175 °C due to LiF liquid-phase sintering and restricts Li evaporation, and a well-developed grain morphology and excellent dielectric properties (ɛ_r = 18.5, Q×f = 87,000 GHz, τ_f = − 18 ppm/°C) was obtained which hold promise in 4G tele-communication applications.