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 (ɛr) decreases from 19.55 to 14.53, quality factor (Q×f) increases from 102,800 to 126,000 GHz and temperature coefficient (τf) decreases from + 15.9 to − 30.08 ppm/°C. High performance microwave dielectric properties of ɛr = 18.5, Q×f = 108,000 GHz, τf = 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 (ɛr = 18.5, Q×f = 87,000 GHz, τf = − 18 ppm/°C) was obtained which hold promise in 4G tele-communication applications.
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