Effect of LiF Addition Strategy on the Sintering of Li2MgTiO4 Microwave Dielectric Ceramics with Cubic Rock Salt Structure

Recently, microwave dielectric ceramics with an oxyfluoride cubic rock salt structure have been widely studied due to their excellent microwave dielectric properties. However, the sintering mechanism of this material, especially the role of F-ions, is not clear. Here, the ceramic samples with two different LiF addition strategies were prepared by a conventional solid-phase reaction method. The sintering mechanisms of both samples were discussed in detail by analyzing the sintering activation energy, F-ions distribution, and concentration of oxygen vacancies by linear shrinkage, SEM-EDS, and XPS. The best microwave dielectric properties were obtained for Li2MgTiO4 +4wt.% LiF (LiF-B) ceramics sintered at 950°C: εr = 18.0, Q×f = 82100GHz, and τƒ = −32.7 ppm/°C.