Improved high q value of MgTiO3-CaTiO3 microwave dielectric ceramics at low sintering temperature

MgTiO3-based ceramics have been prepared with conventional solid-state route. With 5 mol% CaTiO3 addition, 0.95MgTiO3-0.05CaTiO3 ceramics can give εr ∼20–21, Q×f values ∼56,000 (at 7 GHz) and a τ f value of ∼0 ppm/°C. However, sintering temperature still remained above 1400°C. Doping with B2O3 (up to 5 wt%) can effectively promote the densification and the dielectric properties of 0.95MgTiO3-0.05CaTiO3 ceramics. It is found that 0.95MgTiO3-0.05CaTiO3 ceramics can be sintered at 1200°C due to the liquid phase effect of B2O3 addition observed by Scanning Electronic Microscopy. The effect of B2O3 addition on the microwave dielectric properties and the microstructures of 0.95MgTiO3-0.05CaTiO3 ceramics are also investigated. For practical applications, 0.95MgTiO3-0.05CaTiO3 ceramics with 2 wt% B2O3 addition gives: εr ∼21.2, Q×f values ∼62,000 (at 8 GHz), and a τf value of ∼4 ppm/° C.