Improved density and low temperature sintering of Li ₂ Mg ₃ TiO ₆ microwave dielectric ceramics with LiF sintering aid

In order to eliminate the porous structure caused by lithium volatilization and explore the sintering mechanism and structure dependence of dielectric characteristics, lithium fluoride (LiF) as sintering aid was adopted to prepare Li 2 Mg 3 TiO 6 -x LiF (x=0-5 wt.%) samples. The effects of LiF additive on phase components, morphology, sintering characteristics and dielectric characteristics of Li 2 Mg 3 TiO 6 were studied. The results showed that modest LiF addition can reduce sintering temperature from 1280 °C to 900°C. The structure and refinement analysis demonstrated that samples maintain single structure within 0 wt.%≤x≤4 wt.%. The morphology analysis confirmed that the porosity and grain size of Li 2 Mg 3 TiO 6 -x LiF ceramics gradually decreased with increasing LiF. The dielectric constant (ε r ) and quality factor (Q×f) showed a trend of increasing first and then decreasing, which was strongly associated with density, ionic polarization, phase components, lattice energy, packing fraction and grain size. In addition, the Li 2 Mg 3 TiO 6 -4 wt.% LiF sample sintered at 900°C exhibited outstanding dielectric characteristics: ε r =15.57, Q×f=124200 GHz and τ f =-30.32 ppm/°C.