A reduced sintering temperature and improvement in the microwave dielectric properties of Li₂Mg₃TiO₆ through Ge substitution

Abstract In this paper, we demonstrate a strategy to reduce the sintering temperature of titanates through an appropriate amount of Ge substitution for Ti. A series of Li₂Mg₃Ti1-xGexO₆ (x = 0.04, 0.06, 0.08, 0.10, 0.12) ceramics, prepared by a solid-state reaction method, are reported. By controlling the content of the Ge substitution, the sintering temperature of Li₂Mg₃TiO₆ was significantly reduced to 1140 °C. When x = 0.10, the Li₂Mg₃Ti1-xGexO₆ ceramics sintered at 1140 °C for 6 h displayed excellent values of εr = 13.7, Q × f = 131,500 GHz and τf = −34.2 ppm/°C. In addition, the temperature stability was successfully adjusted to be close to zero by adding CaTiO₃ to form a composite ceramic. A temperature stable ceramic 0.96Li₂Mg₃Ti0.9Ge0.1O₆-0.04CaTiO₃ with τf = −3.5 ppm/°C, εr = 14.9 and Q × f = 68,900 GHz was obtained when sintered at 1180 °C. The good dielectric performances of the CaTiO₃-modified Li₂Mg₃Ti0.9Ge0.1O₆ ceramics makes them possible candidates for substrates in microwave integrated circuits