Abstract
57Fe Mössbauer spectra of two synthetic samples of ferrihydrite, recorded at 4.2 K in applied fields of up to 9 T, have been analysed by a mean-field model. The samples exhibit two and six X-ray diffraction peaks. It is shown that only one ferric ion site is present in the mineral, and that in this site the ions are octahedrally coordinated. The spectra show the presence of different magnetic states: ferrimagnetism in two-line ferrihydrite, and antiferromagnetism in six-line ferrihydrite. The ferrimagnetism in two-line ferrihydrite is analysed in terms of random fluctuations arising from the small numbers of ferric ions per particle, and it is shown that the different magnetic states may arise purely as a result of these fluctuations.
Similar content being viewed by others
References
Bigham J. M., Schwertmann U., Carlson L., and Murad E. (1990) A poorly crystallized oxyhydroxysulfate of iron formed by bacterial oxidation of Fe(II) in acid-mine waters: Geochim. Cosmochim. Acta 54, 2743–2758.
Cardile C. M. (1988) Tetrahedral Fe3+in ferrihydrite: 57Fe Mossbauer spectroscopic evidence: Clays & Clay Minerals 36, 537–539.
Chukhrov F. V., Zvyagin B. B., Ermilova L. P., and Gorshkov A. I. (1973) New data on iron oxides in the weathering zone: in Proc. Int. Clay Conf., Madrid, 1970, J. M. Serratosa, ed., Div. de Ciencias C.S.I.C., Madrid, 333–341.
Coey J. M. D. and Readman P. W. (1973) New spin structure in an amorphous ferric gel: Nature 246, 476–478.
Eggleton R. A. and Fitzpatrick R. W. (1988) New data and a revised structural model for ferrihydrite: Clays & Clay Minerals 36, 111–124.
Eggleton R. A. and Fitzpatrick R. W. (1990) New data and a revised structural model for ferrihydrite: Reply: Clays & Clay Minerals 38, 335–336.
Madsen M. B., Morup S., and Koch C. J. W. (1986) Magnetic properties of ferrihydrite: Hyperfine Interactions 27, 329–332.
Manceau A., Combes J.-M., and Calas G. (1990) New data and a revised structural model for ferrihydrite: Comment: Clays & Clay Minerals 38, 331–334.
Murad E. (1988) The Mossbauer spectrum of “well”-crystallised ferrihydrite: J. Magn. Magn. Materials 74, 153–157.
Murad E., Bowen L. H., Long G. J., and Quin T. G. (1988) The influence of crystallinity on magnetic ordering in natural ferrihydrites: Clay Minerals 23, 161–173.
Pankhurst Q. A. (1991) Anisotropy field measurement in barium ferrite powders by applied field Mossbauer spectroscopy: J. Phys. Condens. Matter 3, 1323–1335.
Pankhurst Q. A. and Pollard R. J. (1990) Mossbauer spectra of antiferromagnetic powders in applied fields: J. Phys. Condens. Matter 2, 7329–7337.
Pollard R. J. and Pankhurst Q. A. (1991) Ferrimagnetism in fine feroxyhite particles: J. Magn. Magn. Materials 99, L39–L44.
Pollard R. J. and Pankhurst Q. A. (1992) A comment on the detection of speromagnetism in insulators by Mössbauer Spectroscopy: J. Phys. Condens. Matter 4, L317–L323.
Pollard R. J., Cardile C. M., Lewis D. G., and Brown L. J. (1992) Characterization of FeOOH polymorphs and ferrihydrite using low-temperature, applied-field, Mössbauer spectroscopy: Clay Miner. 27, 57–71.
Pollard R.J., Pankhurst Q. A., and Zientek P. (1991) Magnetism in aluminous goethite: Phys. Chem. Miner. 18, 259–264.
Towe K. M. and Bradley W. F. (1967) Mineralogical constitution of colloidal “hydrous ferric oxides”: J. Colloid Interface Sci. 24, 384–392.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Pankhurst, Q.A., Pollard, R.J. Structural and Magnetic Properties of Ferrihydrite. Clays Clay Miner. 40, 268–272 (1992). https://doi.org/10.1346/CCMN.1992.0400303
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1346/CCMN.1992.0400303