Journal of the American Ceramic Society, Vol.95, No.4, 1394-1397, 2012
Microwave Dielectric Properties of Ca4La2Ti5-x(Mg1/3Nb2/3)(x)O-17 Ceramics
Using the solid-state ceramic route, Ca4La2Ti5-x(Mg1/3Nb2/3)(x)O-17 (0 <= x <= 4) ceramics were prepared, and the phase purity, microstructure, and microwave dielectric properties were investigated. The XRD results suggest the formation of solid solutions for all studied compositions (0 <= x <= 4) and the unit cell volume increases linearly with x. The SEM results also show no evidence of secondary phase and doping (Mg1/3Nb2/3) at Ti site promotes the grain growth. The er of sintered ceramics decreases from 71.86 to 35.23, the Q x f value increases from 15 070 to 21 277 GHz and the tau(f) value varies from 125.2 to -16.7 ppm/degrees C with x increasing from 0 to 4. A near-zero tau(f) (similar to 1.62 ppm/degrees C) is achieved at x = 3 with epsilon(r) similar to 40.45 and Q x f similar to 19 123 GHz.