Chemical and structural properties of the system Fe2O3-Cr2O3 |
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Authors: | S Musi? S Popovi? M Risti? |
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Affiliation: | (1) Rudjer Bokovi Institute, P. O. Box 1016, 41001 Zagreb, Croatia;(2) Physics Department, Faculty of Science, Rudjer Bokovi Institute, PO Box 162, 41001 Zagreb, Croatia |
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Abstract: | Chemical and structural properties of the mixed metal oxides (1–x)Fe2O3+xCr2O3 were studied by different techniques. X-ray powder diffraction showed the existence of solid solutions, (Fe1–x
Cr
x
)2O3, over the whole concentration region, 0x1. The gradual replacement of Fe3+ with Cr3+ ions in samples prepared at 900°C caused changes in unit-cell parameters; most of these changes took place in the region fromx0.3–0.9. The samples having the fraction of Cr2O3 in the region from 0.7–0.8, contained two closely related phases, with slightly different compositions. After an additional heat treatment at 1100°C, these samples contained only one phase.57Fe Mössbauer spectroscopy showed a gradual decrease of hyperfine magnetic field with increasing Cr2O3 content. The sample having the fraction of Cr2O3 of 0.7, and prepared at 900°C, exhibited two separated sextets at room temperature, in comparison with other compositions showing one sextet. It was shown that Fourier transform infrared (FT-IR) spectroscopy is a powerful method for the investigation of structural changes in these solid solutions. The increase in the Cr2O3 content resulted in shifts of the corresponding infrared bands. In addition, a gradual transition of the spectrum typical for -Fe2O3 to the spectrum typical for Cr2O3 was shown. The transition effects observed in the FT-IR spectra were correlated with the X-ray powder diffraction and57Fe Mössbauer spectroscopic results. |
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