• Lisinska-Czekaj, Agata
• Czekaj, D.
• Oleszak, Dariusz
• Jartych, E.

Abstract

<p>The aim of this work was to prepare BiFeO₃ by modified solid-state sintering and mechanical activation processes and to investigate the structure and hyperfine interactions of the material. X-ray diffraction and Mössbauer spectroscopy were applied as complementary methods. In the case of sintering, BiFeO₃ phase was obtained from the mixture of precursors with 3 and 5 % excess of Bi₂O₃ during heating at 1023 K. Small amounts of impurities such as Bi₂Fe ₄O₉ and sillenite were recognized. In the case of mechanical activation, the milling of stoichiometric amounts of Bi ₂O₃ and Fe₂O₃ followed by isothermal annealing at 973 K resulted in formation of the mixture of BiFeO₃, Bi₂Fe₄O₉, sillenite and hematite. After separate milling of individual Bi₂O₃ and Fe ₂O₃ powders, mixing, further milling and thermal processing, the amount of desired BiFeO₃ pure phase was significantly increased (from 70 to 90 %, as roughly estimated). From Mössbauer spectra, the hyperfine interaction parameters of the desired BiFeO₃ compound, paramagnetic impurities of Bi₂Fe₄O₉ and sillenite were determined. The main conclusion is that the lowest amount of impurities was obtained for BiFeO₃ with 3 % excess of Bi ₂O₃, which was sintered at 1023 K. However, in the case of mechanical activation, the pure phase formed at a temperature by 50 K lower as compared to solid-state sintering temperature. X-ray diffraction and Mössbauer spectroscopy revealed that for both sintered and mechanically activated BiFeO₃ compounds, thermal treatment at elevated temperature led to a partial eliminating of the paramagnetic impurities. © 2013 Versita Warsaw and Springer-Verlag Wien.</p>

Topics

• impedance spectroscopy
• compound
• phase
• x-ray diffraction
• grinding
• milling
• annealing
• activation
• ceramic
• sintering
• Mössbauer spectroscopy