Sintering behavior and microwave dielectric properties of SrTiO3 with various Sr/Ti ratio

In order to increase the speed and bandwidth for the tele-communications, the development of microwave dielectric ceramic is essential. The strontium titanate (SrTiO3) is one of the dielectric ceramic which is widely used. In the present study, the SrTiO3 powder with various Sr/Ti ratios is successfully produced using solid state reaction. The Sr/Ti ratio varies from 0.909 to 1.111. The characteristics of the specimens with different Sr/Ti ratio after sintering at different temperature are determined. We found that Sr/Ti ratio strongly affected the shrinkage rate, microstructure, and chemical defect concentration. And the microwave dielectric properties depend on the density and Sr/Ti ratio. The Ti-rich specimens exhibit a higher density (=99%), permittivity (=300), and quality factor (=3000) than the Sr-rich specimens. An aging effect on the quality factor is observed. After aging for one month, the quality factor of the specimens with Sr/Ti of 0.952 increases to 18,000.