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 <TEX>$Nb^{5+}\;and\;Ta^{5+}$</TEX> doped BaTi<TEX>$O_3$</TEX> solid solutions have been investigated. The samples were sintered at temperatures ranging from 1250 to 1350 <TEX>${^{\circ}C}$</TEX> 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 <TEX>$Nb^{5+}\;and\;Ta^{5+}$</TEX> ions into the BaTi<TEX>$O_3$</TEX> crystal lattice. The X-ray diffraction peaks of (111), (200) and (002) planes of BaTi<TEX>$O_3$</TEX> solid solution doped with different fractions of <TEX>$Nb^{5+}\;and\;Ta^{5+}$</TEX> were investigated. The dielectric properties were analyzed and the relationship between the properties and structure of doped BaTi<TEX>$O_3$</TEX> was established. The fine-grain and high density of the doped BaTi<TEX>$O_3$</TEX> 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% <TEX>$Ta^{5+}$</TEX> doped BaTi<TEX>$O_3$</TEX> solid solution was <TEX>$\sim$</TEX>110 <TEX>${^{\circ}C}$</TEX> with a dielectric constant of 3000 at room temperature. At temperatures above the Curie temperatures, the dielectric constant followed the Curie-Weiss law.