Microstructural characterization and dielectric properties of barium titanate solid solutions with donor dopants

Abstract

The correlation between the sintering temperature and dielectric properties in the Nb5+ and Ta5+ doped BaTiO3 solid solutions have been investigated. The samples were sintered at temperatures ranging from 1250 to 1350 °C for 4 h in air. SEM, XRD and SEM/EDS techniques were used to examine the structure of the samples with particular focus on the incorporation of Nb5+ and Ta5+ ions into the BaTiO3 crystal lattice. The X-ray diffraction peaks of (111), (200) and (002) planes of BaTiO3 solid solution doped with different fractions of Nb5+ and Ta5+ were investigated. The dielectric properties were analyzed and the relationship between the properties and structure of doped BaTiO3 was established. The fine-grain and high density of the doped BaTiO3 ceramics resulted in excellent dielectric properties. The dielectric properties of this solid solutions were improved by adding a small amount of dopants. The transition temperature of the 1.0 mole% Ta5+ doped BaTiO3 solid solution was ̃ 110 oC with a dielectric constant of 3000 at room temperature. At temperatures above the Curie temperatures, the dielectric constant followed the Curie-Weiss law.