Fourier Transform Infrared Studies of Aluminous Goethites and Hematites

Fysh, Stuart A.

doi:10.1346/ccmn.1983.0310507

Cited by 48 publications

(27 citation statements)

References 16 publications

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“…Namduri et al [9] assigned the bands at 540 cm -1 and 570 cm -1 as analytical bands of hematite and magnetite, respectively. Fysh and Fredericks [18] working with hematite at high temperature, reported bands at 470 and 550 cm-1. Desai et al [19] showed bands of hematite at 476 and 616 cm -1 .…”

Section: B Infrared Spectroscopy (Ft-ir)mentioning

confidence: 99%

Quantitative approach in iron oxides and oxyhydroxides by vibrational analysis

Betancur¹

2012

Opt. Pura Apl.

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Section: B Infrared Spectroscopy (Ft-ir)mentioning

confidence: 99%

Quantitative approach in iron oxides and oxyhydroxides by vibrational analysis

Betancur¹

2012

Opt. Pura Apl.

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“…Electron diffraction studies (Goltztaub, 1935;van Oosterhout, 1960;Cornell et al, 1983) have shown that goethite crystals are commonly elongated in the [001 ] direction, although factors such as pH, temperature, and the presence of foreign elements in the synthetic system can influence the morphology of the final product. Synthetic goethites doped with A1 have been widely studied (e.g., Fysh and Clark, 1982;Fysh and Fredericks, 1983;Murad and Schwertmann, 1983;Schulze, 1984;Mann, 1983). AI substitutes directly in goethite for Fe in octahedral sites because the ionic radius of A1 (0.67 A) (Shannon and Prewitt, 1969) is similar to that of Fe 3 § (0.78 A).…”

Section: Introductionmentioning

confidence: 99%

Influence of Silicon and Phosphorus on Structural and Magnetic Properties of Synthetic Goethite and Related Oxides

Quin

1988

Clays and clay miner.

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Abstract--A series of synthetic goethites containing varying amounts of Si and P dopants were characterized by X-ray powder diffraction, electron diffraction, microbeam electron diffraction, and M6ssbauer spectroscopy. Very low level incorporation produced materials having structural and spectral properties similar to those of poorly crystalline synthetic or natural goethite. At higher incorporation levels, mixtures of noncrystalline materials were obtained which exhibited M6ssbauer spectra typical of noncrystalline materials mixed with a superparamagnetic component. Microbeam electron diffraction indicated that these mixtures contained poorly crystalline goethite, poorly crystalline ferrihydrite, and a noncrystalline component. If the material was prepared with no aging of the alkaline Fe 3+ solution before the addition of Na2HPO4 or Na2SiO3, materials were obtained containing little if any superparamagnetic component. If the alkaline Fe 3+ solution was aged for 48 hr before the addition, goethite nuclei formed and apparently promoted the precipitation of a superparamagnetic phase. The M6ssbauer-effect hyperfine parameters and the saturation internal-hyperfine field obtained at 4.2 K were typical of those of goethite; however, the M6ssbauer spectra indicated that the ordering temperature, as reflected in the relaxation rate and/or the blocking temperature, decreased with increasing incorporation of Si and P. The complete loss of crystallinity indicates that Si and P did not substitute for Fe, but rather adsorbed on crystal-growth sites, thereby preventing uniform crystal growth.

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“…The positions of the IR absorption bands observed here result from both AI-and OH-substitution in the hematite lattice. Aluminium substitution causes a shift to higher absorption values in comparison with pure hematite [15,16], whereas an increasing hydroxyl group content in the hematite anion sublattice displaces the absorption bands towards lower frequencies [17]. From the infrared spectra presented in Fig.…”

Section: Resultsmentioning

confidence: 96%

Temperature effects on coprecipitated Al, Fe-hydroxides during hydrothermal transformations

Wolska

Szajda

1987

Journal of Thermal Analysis

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Studies of the hydrothermal behaviour of coprecipitated A1, Fe-hydroxides with aluminium contents from 5 to 50 tool% reveal that the temperature of the hydrothermal process strongly affects the reciprocal influence of AI(III) and Fe(III) ions on the direction of transformation of the initially amorphous gels.It has been found by X-ray diffraction analysis and IR spectroscopic investigations that at 373 K, up tO 10 mol% A1, well-crystallized At-substituted hydrohematite is formed; at 15-25 mol% AI the crystallinity falls offand the products are amorphous; and at 27.5-50 mol% A1 the poorly-crystallized hydrohematite appears, accompanied by different crystalline aluminium trihydroxides, the equilibria of which depend essentially on the AI : Fe ratio and on the pH of the medium.The hydrothermal process carried out at 413 K yields the Al-substituted protohematite for samples with 15-50 mol% A1, whereas the unique crystalline phase of Al-hydroxide is a wellcrystallized boehmite.

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Fourier Transform Infrared Studies of Aluminous Goethites and Hematites

Cited by 48 publications

References 16 publications

Quantitative approach in iron oxides and oxyhydroxides by vibrational analysis

Quantitative approach in iron oxides and oxyhydroxides by vibrational analysis

Influence of Silicon and Phosphorus on Structural and Magnetic Properties of Synthetic Goethite and Related Oxides

Temperature effects on coprecipitated Al, Fe-hydroxides during hydrothermal transformations

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