A study of aluminum-substituted iron dextran complexes by Mossbauer spectroscopy and X-ray diffraction

Two aluminum-substituted iron dextran complexes and one nonsubstituted have been synthesized and characterized by Mossbauer spectroscopy over a wide t emperature range (10-298 K) and by X-ray powder diffraction at room tempera ture. The mean coherence lengths in the directions perpendicular to (211) a nd (200) are different, indicating that the core iron oxide materials are o blong in shape. The X-ray diffraction patterns of all complexes are very si milar, with broad, weak peaks at 5.0, 3.3, 2.5, 2.25, 1.6, and 1.8 Angstrom . These values are consistent with cell-contracted akaganeite, beta -FeOOH. The three samples exhibit different temperatures for the onset of magnetic splitting in their Mossbauer spectra. The Mossbauer spectra obtained at ro om temperature can be adequately fitted with a model-independent distributi on of quadrupole doublets, while at low temperatures a superposition of dis tributions of sextets and doublets is required. The obtained Mossbauer para meters are in line with the structural features. This is the first report o n nanoscale aluminum-substituted iron oxides as a component of iron dextran .