Microstructure and dielectric properties of SrTiO3-PbTiO3-CaTiO3 ceramics

The electrical properties and microstructures of SrTiO3-PbTiO3-CaTiO3-Bi2O3-TiO2 systems were investigated. It was found that the materials had two inhomogeneous regions, called ''grain core-grain shell'', by held-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) observations. The dielectric constant showed two peaks. The dielectric constant at temperatures below 0 degrees C decreased, whereas that at temperatures above 100 degrees C increased slightly under DC bias field. D-E loops revealed that the ferroelectric state existed at temperatures below 0 degrees C, and the paraelectric-like state existed at temperatures above 100 degrees C. The observed frequency dependence and aging phenomena showed that this material was a relaxer. A relationship between the electrical properties and microstructure has been proposed.