Optical and electrical properties of Ba1−xSrxTiO3 nanopowders at different Sr2+ ion content

• Published in: Journal of materials science. Materials in electronics 2013, Vol.24 (9), p.3284-3291
• Main Authors: Rashad, M. M., Turky, A. O., Kandil, A. T.
• Format: Article
• Language: English
• Subjects: Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electronics; Exact sciences and technology; Materials; Materials Science; Nanopowders; Nanoscale materials and structures: fabrication and characterization; Optical and Electronic Materials; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-013-1244-9

Barium strontium titanate (BST) Ba 1− x Sr x TiO 3 nanopowders have been successfully synthesized using oxalate precursor route. The effect of Sr 2+ ion content from 0.3 to 0.7 on the crystal structure, crystallite size, microstructure, electrical and optical properties was systematically studied. The results revealed that well crystalline single BST phase was formed by annealing the oxalate precursor at 1,000 °C for 2 h. The crystallite size of the BST powders was decreased with increasing the Sr 2+ ion molar ratios. The crystallite size was decreased from 56.0 to 33.1 nm when the Sr 2+ ion content increased from 0.3 to 0.7. Additionally, the lattice parameter ( a ), unit cell volume and X-ray density of BST ware decreased whereas the porosity, % were increased with Sr 2+ ion concentration. The BST phase appeared as cubic-like structure. The spectrophotometer measurement results demonstrated that the room temperature band gap energy varied with the Sr 2+ ion composition x . The band gap energy was shifted to low energy and it was decreased from 3.6 to 3.2 eV with increasing the Sr 2+ ion content from 0.3 to 0.7. Moreover, the DC resistivity was enhanced with increasing the Sr 2+ ion ratio. The dielectric response obtained for the stressed samples corresponds to a true resonance rather than a dispersion process with a characteristic frequency around 1 GHz at room temperature. However, the peaks commonly observed at GHz frequency were changed with varying the Sr 2+ ion composition. The high imaginary components of dielectric permittivity for x  = 0.3 was found at higher frequency region around 1.6 GHz compared with the samples with x values of 0.5 and 0.7 in which the frequency regions were around 1.25 and 1.15 GHz, respectively.