Sintering behavior of 0.95MgTiO3-0.05CaTiO3 ceramics with high densification, high Q and enhanced mechanical properties for 5G massive MIMO technology: Effect of particle gradation

An increase in the requirements for microwave dielectric materials was brought on by the quick growth of communication technologies. In this study, the sintering problems including the narrow sintering densification range and high sintering temperature of 0.95MgTiO3-0.05CaTiO3 (95MCT) ceramics with high densification and high Q, as one of the candidate materials for 5G filters, were discussed and overcome through the particle gradation with sub-micrometric and micrometric powders according to closest packing models. It was found that sub-micrometric (0.7-1 mu m) 95MCT powder particles agreed well with the Andreasen model, while micrometric (1-3 mu m) particles agreed better with the Dinger-Funk model. With increasing of sub-micrometric powders, the activation energy decreased from 926.01 +/- 75.49 to 569.49 +/- 31.57 kJ/mol, and the relative density of samples which contained 20-60% fine powders were increased to 98%. The average grain size and grain homogeneity decreased from 7.36 mu m to 2.54 mu m and 3.36 to 1.79, respectively, to improve the mechanical properties. The results show that the powder grading further improved the comprehensive performance of 95MCT, and the best performance point was J1 which exhibited excellent microwave dielectric properties with epsilon r = 21.1, Qf = 82000 GHz, tau f = -0.9 ppm/degrees C, RD = 98.2%, sigma f = 178.7 MPa and HV = 8.78 GPa after sintering at 1225 degrees C for 3h.