Characterization and dielectric behavior of a new dielectric ceramics Ca(Mg1/3Nb2/3)O3-(Ca0.8Sr0.2)TiO3 at microwave frequencies

The crystal structures, phase compositions and the microwave dielectric properties of the (1-x)Ca(Mg1/3Nb2/3)O-3-x(Ca0.8Sr0.2)TiO3 perovskite-based composites prepared by the conventional solid state route have been investigated. The formation of solid solution is confirmed by the XRD patterns. A rapid grain growth is observed at temperatures higher than 1470 degrees C, which would lead to a decrease in the density and Qxf of the ceramics. The temperature coefficient of resonant frequency increases with increasing (Ca0.8Sr0.2)TiO3 content and tunes through near zero at x = 0.3. Specimen using 0.7Ca(Mg1/3Nb2/3)O-3-0.3(Ca0.8Sr0.2)TiO3 possesses an excellent combination of microwave dielectric properties: epsilon(r)similar to 43.75, Qxf similar to 45.200GHz (where f=6.3GHz is the resonant frequency) and tau f similar to-4.2 ppm/degrees C. It is proposed as a suitable candidate material for small-sized GPS patch antennas. (C) 2009 Elsevier B.V. All rights reserved.