Phase evolution and microwave dielectric properties of ceramics with nominal composition Li2x(Zn0.95Co0.05)2-xSiO4 for LTCC applications

Li(2)x(Zn0.95Co0.05)(2) - xSiO4 (0 <= x <= 1) ceramics were prepared through the conventional solid-state route. A fixed amount of Li2O-MgO-ZnO-B2O3-SiO2 (LMZBS) glass was used as a sintering aid to help lower the sintering temperature to around 900 degrees C. The effects of part lithium-ion substitution on the phase formation, sintering behaviour, microstructures and microwave dielectric properties of the ceramics were systematically investigated. When x = 0.25, the sample achieved a dense microstructure and exhibited excellent microwave dielectric properties of epsilon(r) = 6.47, Q x F = 131 579 GHz and tau(f) = - 27.12 ppm degrees C-1. For its practical application in low-temperature co-fired ceramics (LTCC), large positive tau(f) of CaTiO3 was used to adjust the sf value of the composite ceramic to nearly zero. The composite ceramic of 0.975Li(0.5)(Zn0.95Co0.05)(1.75)SiO4-0.025CaTiO(3) sintered at 900 degrees C also presented good microwave dielectric properties of epsilon(r) = 6.773, Q x F = 69 177 GHz and tau(f) = -2.45 ppm degrees C-1