Sintering characteristics, crystal structure, and microwave dielectric properties of Li2(Mg0.9A0.1)4TiO7 (A = Co2+, Ni2+, Mg2+, Zn2+, Ca2+)

The Li 2 (Mg 0.9 A 0.1 ) 4 TiO 7 (A = Co 2+ , Ni 2+ , Mg 2+ , Zn 2+ , Ca 2+ ) ceramics were prepared by the conventional solid-state reaction method. A series of Li 2 (Mg 0.9 A 0.1 ) 4 TiO 7 ceramics were investigated in regard to the sintering temperatures, crystal structures and dielectric properties. The Li 2 (Mg 0.9 A 0.1 ) 4 TiO 7 ceramic exhibited a single phase of Li 2 Mg 4 TiO 7 , and the Rietveld refinement was used to analyze the crystal structure. The Li 2 (Mg 0.9 Ca 0.1 ) 4 TiO 7 ceramics could be sintered below 1350 °C with high densities, high dielectric constants and near zero τ f values. The maximum Q · f value of Li 2 (Mg 0.9 Zn 0.1 ) 4 TiO 7 was higher than that of Li 2 (Mg 0.9 A 0.1 ) 4 TiO 7 (A = Co 2+ , Ni 2+ , Mg 2+ , Ca 2+ ). The optimum microwave dielectric properties of ε r  = 14.77, a high Q · f value of 162,200 GHz and τ f  = − 4.30 ppm/°C were achieved in Li 2 (Mg 0.9 Zn 0.1 ) 4 TiO 7 ceramic sintered at 1500 °C. In addition, Li 2 (Mg 0.9 Ca 0.1 ) 4 TiO 7 ceramic sintered at 1300 °C exhibited the suitable dielectric properties with a high ε r value of 15.79, Q · f  = 100,300 GHz and a near zero τ f value of − 1.43 ppm/°C.