Synthesis, structural and spectroscopic characterizations of maghemite gamma-Fe2O3 prepared by one-step coprecipitation route

摘要

Maghemite (gamma-Fe2O3) is synthesized by one step coprecipitation method from mixed salt solutions containing Fe(II) and Fe(III) salts. This material was characterized using Rietveld refinement of the X-ray powder diffraction, heating stage Raman microscopy and Mossbauer spectroscopies. The Rietveld refinement of XRD pattern has indicated that the gamma-Fe2O3 shows a cubic cell structure. The superstructure reflection related to the long-range ordering of cation lattice vacancies was not detected in the diffraction pattern. The extra peaks corresponding to the Lepidocrocite phase gamma FeOOH in a small amount were observed in the XRD pattern. The crystallite size of maghemite compound is 18 nm calculated using Williamson-Hall method. Using Mossbauer spectroscopy, the result of Rietveld refinement was confirmed by the presence of magnetic sextet arising from the metallic iron of gamma-Fe2O3, and a paramagnetic doublet inferring the presence of paramagnetic iron of gamma FeOOH. Heating stage Raman microscopy reveals that the temperature of transition to maghemite phase up to hematite is 550 degrees C. The heating of our maghemite (gamma-Fe2O3) powder up to 550 degrees C yields a single phase of Hematite hexagonal-corundum structure with R (3) over barc space group. (C) 2015 Elsevier B.V. All rights reserved.