Dielectric Properties of Ba0.7Sr0.3TiO3 Ceramics with Different Grain Size

Ba 0.7 Sr 0.3 TiO 3 ceramics with different grain sizes were prepared by the sol-gel method. The temperature dependence of the dielectric properties of the ceramics was studied. There are two dielectric peaks, corresponding to the cubic-tetragonal(C-T) and tetragonal-orthorhombic(T-O) phase transitions, respectively. With the decrease of grain size, the Curie temperature decreases while the T-O transition temperature increases, and the two dielectric peaks become lower and broader and eventually disappear in the following sequence: T-O, C-T. The ferroelectric critical size and the grain size dependence of the dielectric constant are also discussed.