ZHANG Feng, XU Qing, CHEN Wen, HUANG Duanping, LIU Hanxing, ZHOU Jian

（ School of Materials Science and Engineering, Wuhan Univers ity of Technology, 430070）

Abstract: Ba_xSr_{1- x}TiO₃(x=0.5，0.6，0.7) powders were synthes ized by a sol- gel method us ing EDTA and citric as mixed complexing agents. The formation process,crystal structure and morphology of the synthes ized powders were characterized by TG- DSC,XRD and SEM. The results indicate that fine and homogeneous powders (~100nm) with a pure perovskite structure can be produced by calcining at 550℃ for 1h. The ceramics sintered at 1250- 1300℃ display a dense micros tructure, showing average grain sizes of 3~5μm and relatively densities above 95%. The dielectric properties of Ba_xSr_{1- x}TiO₃(x=0.5，0.6，0.7) ceramics were inves tigated. A paraelectric state at room temperature was ascertained for all the ceramics , and the permittivity increases with increasing Sr content at an identical frequency. In the case of room temperature and 1 kHz, the ceramics provide the permittivity value of 1540,3220 and 4750 together with dielectric loss values of 0.2%,0.2% and 2.1% at x=0.5, x=0.6 and x=0.7, respectively.

Keywords: inorganic non- metallic materials , Ba_xSr_{1- x}TiO₃, sol- gel process , dielectric properties