Ultralow-loss and temperature-stable self-composite microwave dielectric ceramic of Li4MgSn2O7–Li2Mg3SnO6 for LTCC applications

Abstract A self-composite ceramic of Li4MgSn2O7 (L4MS) and Li2Mg3SnO6 (L2MS) phases with compositions Li2/3(1-x)Sn1/3(1-x)MgxO (x = 1/6)-y wt.%LiF was for the first time prepared by a conventional solid-state reaction method. The XRD results indicate that L4MS and L2MS((MgO)ss) phases can stably coexist only as sintering temperature is below 1200 °C, and their relative contents can be regulated by changing sintering temperature. The sintering aid LiF was used to not only reduce sintering temperature to suppress the L4MS decomposition, but also obtain the dense ceramic body. Excellent microwave dielectric properties of er = 13.4, Qxf = 123,440 GHz and near-zero τf ∼ −4.3 ppm/°C were obtained in the y = 5 sample sintered at 1000 °C for 6 h. For LTCC applications, both good chemical compatibility with Ag and optimum microwave dielectric properties of er = 13.0, Qxf = 78,180 GHz and τf = −9 ppm/°C were achieved in the sample with y = 6 as sintered at 850 °C, showing great application potentials in future microwave devices.