Influence of sintering temperature on dielectric properties and crystal structure of corundum-structured Mg4Ta2O9 ceramics at microwave frequencies

Microwave dielectric properties of corundum-structured Mg4Ta2O9 ceramics were investigated as a function of sintering temperatures by an aqueous sol gel process. Crystal structure and microstructure were examined by X-ray diffraction (XRD) technique and field emission scanning electron microscopy (FE-SEM). Sintering characteristics and microwave dielectric properties of Mg4Ta2O9 ceramics were studied as a function of sintering temperature from 1250 degrees C to 1450 degrees C. With increasing sintering temperature, the density, epsilon(r) and Qf values increased, saturating at 1300 degrees C with excellent microwave properties of epsilon(r)=11.9, Qf=195,000 GHz and tau(f)=-47 ppm/degrees C. Evaluation of dielectric properties of Mg4Ta2O9 ceramics were also analyzed by means of first principle calculation method and ionic polarizability theory. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.