Low-temperature sintering LiF-doped Li4Mg3[Ti0·6(Mg1/3Nb2/3)0.4]2O9 microwave dielectric ceramics for LTCC applications

Abstract

Li4Mg3 [Ti0·6(Mg1/3Nb2/3)0.4]2O9 (LMT0.6 (MN)0.4O) ceramics doped with 1–5 wt% lithium fluoride (LiF) were prepared through a conventional solid-state reaction at a relatively low sintering temperature. The influences of the LiF additive on the micromorphology, crystal phase composition, and sintering behavior, as well as the microwave dielectric properties of the LMT0.6 (MN)0.4O ceramics were explored in depth. The addition of the LiF sintering additive reduced the densification temperature of the LMT0.6 (MN)0.4O ceramics from 1450 °C–950 °C. X-ray powder diffractometer patterns indicated that a single phase formed for all experimental samples. Scanning electron microscopy photographs revealed that dense and homogeneous microstructures were obtained at 950 °C for the LMT0.6 (MN)0.4O ceramics with 3–5 wt% LiF. Additionally, the optimized microwave dielectric properties, including εr = 16.24, Q·f = 107,828 GHz (at 8.13 GHz), and τf = −6.25 ppm/°C were achieved in the prepared LMT0.6 (MN)0.4O ceramics with 4 wt% LiF at the sintering temperature of 950 °C. Furthermore, the excellent chemical compatibility between this component and silver were confirmed based on the results of XRD and EDS analyses, suggesting that the LMT0.6 (MN)0.4O ceramics with 4 wt% LiF could be a suitable material for the application of low temperature co-fired ceramics.