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, 0.95MgTiO(3)-0.05CaTiO(3) ceramics can give epsilon (r) similar to 20-21, Q X f values similar to 56,000 (at 7 GHz) and a tau (f) value of similar to0 ppm/degreesC. However, sintering temperature still remained above 1400 degreesC. Doping with B2O3 (up to 5 wt%) can effectively promote the densification and the dielectric properties of 0.95MgTiO(3)-0.05CaTiO(3) ceramics. It is found that 0.95MgTiO(3)-0.05CaTiO(3) ceramics can be sintered at 1200 degreesC 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 0.95MgTiO(3)-0.05CaTiO(3) ceramics are also investigated. For practical applications, 0.95MgTiO(3)-0.05CaTiO(3) ceramics with 2 wt% B2O3 addition gives: epsilon (r) similar to 21.'2, Q X f values similar to 62,000 (at 8 GHz), and a tau (f) value of similar to4 ppm/degreesC. (C) 2001 Elsevier Science Ltd. All rights reserved.