Structural, microstructural and Mossbauer study of BiFeO_3 synthesized at low temperature by a microwave-hydrothermal method

摘要

Multiferroic BiFeO_3 has been rapidly synthesized by a microwave - hydrothermal method using nitrates as the metallic source. Structural characterization was performed by thermal analysis, X-ray diffraction and transmission electron microscopy. Generally accepted trigonal space group R3c, as well as recently suggested monoclinic symmetries, were assayed in the search for the best fit. Due to the ambiguity of the Rietveld refinement to distinguish between crystal systems, a micro-diffraction and HRTEM study has been performed. The best solution was obtained with the trigonal model. The room-temperature Mossbauer spectra reveal the presence of a small fraction (2%) of iron in low spin configuration.