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

Li 4 Mg 3 [Ti 0 · 6 (Mg 1/3 Nb 2/3 ) 0.4 ] 2 O 9 (LMT 0.6 (MN) 0.4 O) 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 LMT 0.6 (MN) 0.4 O ceramics were explored in depth. The addition of the LiF sintering additive reduced the densification temperature of the LMT 0.6 (MN) 0.4 O 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 LMT 0.6 (MN) 0.4 O ceramics with 3–5 wt% LiF. Additionally, the optimized microwave dielectric properties, including ε r  = 16.24, Q·f  = 107,828 GHz (at 8.13 GHz), and τ f  = −6.25 ppm/°C were achieved in the prepared LMT 0.6 (MN) 0.4 O 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 LMT 0.6 (MN) 0.4 O ceramics with 4 wt% LiF could be a suitable material for the application of low temperature co-fired ceramics.