Ethylene Glycol-Assisted Hydrothermal Synthesis and Structural and Dielectric Properties of ${\text{SrBi}}_{{{\text{2 - y}}}} Y_{{\text{y}}} Nb_{{{\text{2 - x}}}} V_{{\text{x}}} {\text{O}}_{9}$ (0$\le$x$\le$0.2 and 0$\le$y$\le$0.2) Ceramics

Abstract

Ethylene glycol-assisted hydrothermal synthesis was used to prepare $\mathrm{SrBi}_{\mathrm{2}-\mathrm{y}}\mathrm{Y}_{\mathrm{y}}\mathrm{Nb}_{\mathrm{2}-\mathrm{x}}\mathrm{V}_{\mathrm{x}}\mathrm{O}_{9}$ (x/y= 0/0, 0/0.2, 0.05/0.1, 0.1/0.05 and 0.2/0) ceramics. Several techniques were used for determining the crystal structure, microstructure, and dielectric properties. All compounds crystallize in the orthorhombic structure without any minor secondary phases. However, there is no correlation between lattice parameters and V/Y ratios. A slight difference was noticeable in the Fourier transform infrared spectroscopy (FTIR) characteristics of these samples. Scanning electron microscopy (SEM) analysis showed that the ceramics also consist of plate-like grains. It turned out that 0.05/0.1 or 0.1/0.05 ratios enhance the dielectric properties at room temperature. As a function of temperature, the bismuth ion, which has a lone pair electron, might emphasize the polarizability, leading to an increase in the Curie temperature. Furthermore, the high ac conductivity is caused by a large amount of space charge carriers arising mainly from oxygen vacancies.