Preparation, microstructure and microwave dielectric properties of ZrxTi1-xO4 (x=0.40-0.60) ceramics

ZrxTi1−xO4 (x=0.40–0.60) ceramics sintered without additives were prepared from powders made by the coprecipitation of metal salts from aqueous solutions in order to investigate the existence range of a homogeneous phase and the relationships between composition, microstructure and the dielectric properties. XRD, TEM, SEM, EDS, and the dielectric measurements were used to characterize the products. A homogeneous solid solution was obtained. Its crystal structure was isomorphous with ZrTiO4. The variation of the lattice parameters with TiO2 content was discussed. The optimum sintering temperature of samples was dependent of composition. TiO2 suppressed the densification and acted as a grain growth enhancer during the sintering process. With the increase in TiO2 content the relative densities of the sintered bodies decrease, while the grain sizes increase. The dielectric properties at microwave frequency (1.8 GHz) in this system, especially Q value, were poor, due to low densification, impurities and lattice defects. The dielectric constant εr and Q value exhibited a significant dependence on the relative density and composition. Both εr and Q increased with the increase in relative density, but they were primarily influenced by the composition and the effect of the relative density could be ignored when the relative density was greater than 90% theoretical. εr increased slightly with increasing TiO2 content, while Q value decreased.