The effect of Ga3+ addition on the sinterability and microwave dielectric properties of RE3Al5O12 (Tb3+, Y3+, Er3+ and Yb3+) garnet ceramics

The RE3Al5O12 (RE=Tb, Y, Er, Yb) ceramics have been prepared by the mixed oxide route and the influence of Ga3+ doping on their properties is investigated. The intrinsic Y3Al5O12 (YAG) ceramic sintered at 1650 degrees C for 4 h showed good dielectric properties; (epsilon(r)=10.1, Q(u) x f= 65,000 GHz, tau(f)= -45 ppm/degrees C). Addition of Ga2O3 was found to be beneficial in improving the densification of Tb3Al5O12, Er3Al5O12 and Yb3Al5O12 except Y3Al5O12 where Nb2O5 is the better choice. Among Ga3+ added samples, the composition Yb3Al5O12 + 1 wt% Ga2O3 showed good microwave dielectric properties: epsilon(r)= 10.3, Q(u) x f=50,000 GHz, tau(f)= -58 ppm/degrees C. The Y3Al5O12 doped with 1 wt% Nb2O5 has epsilon(r)= 10.7, Q(u) x f=120,000 GHz and tau(f) = -45 ppm/degrees C. The ceramics have good thermal properties (CTE=2-3 ppm/degrees C, lambda=2-12 W/m K). (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.