Structure and properties analysis for low-loss (Mg1−xCox)TiO3 microwave dielectric materials prepared by reaction-sintering method

(Mg1−xCox)TiO3 (x = 0.00–0.09) ceramics were prepared by reaction sintering method. The correlations of crystal structure and the properties were analyzed on the basis of Rietveld refinement for specimens with different x. For x ≤ 0.5, solid solution phases with the ilmenite structure were obtained, which can be confirmed by the X-ray diffraction patterns and the lattice parameters measured. Whereas for x > 0.05, secondary phase was detected besides the main phase. Dielectric properties were closely related with theoretical dielectric polarizabilities, packing fraction and average octahedral distortion. By increasing x from 0.00 to 0.09, the Q × f value of the specimen decreased from a maximum of 289,400 GHz to 228,100 GHz. A fine combination of microwave dielectric properties (ɛr ∼ 16.1, Q × f ∼ 289,400 GHz, τf ∼ −54.4 × 10−6/°C) was achieved for MgTiO3 ceramics sintered at 1350 °C for 4 h.