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

• The Rietveld refinement of maghemite (γ-Fe2O3).
• Mössbauer spectroscopy at 300 K and 77 K of maghemite (γ-Fe2O3).
• Raman and heating stage Raman spectroscopy of maghemite (γ-Fe2O3).
• The Rietveld refinement of the Hematite (α Fe2O3).
• Raman spectroscopy of Hematite (α Fe2O3).

Maghemite (γ-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 Mössbauer spectroscopies. The Rietveld refinement of XRD pattern has indicated that the γ-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 γ 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 Mössbauer spectroscopy, the result of Rietveld refinement was confirmed by the presence of magnetic sextet arising from the metallic iron of γ-Fe2O3, and a paramagnetic doublet inferring the presence of paramagnetic iron of γ FeOOH. Heating stage Raman microscopy reveals that the temperature of transition to maghemite phase up to hematite is 550 °C. The heating of our maghemite (γ-Fe2O3) powder up to 550 °C yields a single phase of Hematite hexagonal-corundum structure with R3¯c space group.

Mössbauer spectrum of γ-Fe2O3 sample, recorded at 300 K.Figure optionsDownload as PowerPoint slide