Sintering effects on dielectric properties of (Ba,Sr)TiO3 ceramics

The sintering effect on transition parameters and dielectric characteristics of Ba0.8Sr0.2TiO3 (BST 80/20) ceramics prepared by the conventional mixed-oxide processing technique was studied. Grain structure analysis performed by a scanning electron microscope (SEM) and X-ray diffraction studies showed differences in grain size and contents of crystal phase within the ceramics sintered at constant temperature for a variety of sintering times. The phase transitions and dielectric properties were investigated by measuring the dielectric constant ε′, the loss factor tan δ and the remanent polarization Pr as a function of temperature. The frequency dependence of ε′(T) and tan δ(T) characteristics was also studied. It was shown that the maximal values of the dielectric constant and the remanent polarization are in general proportional to the content of the crystal phase in the volume of the studied ceramics.