Microstructure and dielectric properties of barium–strontium titanate with a functionally graded structure

A functionally graded perovskite material with varying Ba/Sr ratio was known to have a broad transition temperature and as a result it shows a low temperature coefficient and high dielectric constant in a wide temperature range. A multi-layered barium/strontium titanate functionally graded material was fabricated. Optical/scanning electron microscopy, energy dispersive spectrocsopy, and X-ray diffractometer were used for microstructural, chemical, and phase analysis, respectively. An impedance/gain-phase analyzer was used for dielectric constant measurement. The microstructure and dielectric property of BaTiO3–SrTiO3 system display various gradient distributions corresponding to constitutional change. The average grain size of Ba1–xSrxTiO3 phase was reduced as increasing the volume fraction of strontium. The dielectric properties of BaTiO3–SrTiO3 functionally graded materials were discussed in terms of microstructure and chemical composition.