Dielectric and optical properties of Ba5AFe0.5Ta9.5O30 (A = K, Li) tungsten bronze ceramics

• Published in: Journal of materials science. Materials in electronics 2013-10, Vol.24 (10), p.3891-3896
• Main Authors: Su, Congxue, Fang, Liang, Liu, Laijun, Xiang, Fei, Zhang, Hui, Kuang, Xiaojun
• Format: Article
• Language: English
• Subjects: Applied sciences; Catalytic methods; Characterization and Evaluation of Materials; Chemistry and Materials Science; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Dielectric loss and relaxation; Dielectric properties of solids and liquids; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Electronics; Exact sciences and technology; Materials; Materials Science; Methods of nanofabrication; 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
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-013-1335-7

Two novel Ba 5 AFe 0.5 Ta 9.5 O 30 (A = K, Li) ceramics were fabricated through a conventional solid-state sintering process. Both samples were paraelectric phase with tetragonal tungsten bronze structure at room temperature. Dielectric response of the samples was studied by using AC impedance spectroscopy and universal dielectric relaxation law in detail. Dielectric relaxation at high temperatures is attributed to the oxygen vacancies induced by the evaporation of alkali oxide. The relaxation activation energy of the ceramics is lower than half of the band gap E g obtained by UV–Vis spectroscopy, which resulted from the emergence of oxygen vacancies at high temperatures. In the visible light region, the samples showed strong absorption with a band gap of about 2.7 eV, which could be applied as a visible light irradiation photocatalyst.