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The diffusion of Fe2+ ions in spinels with relevance to the process of maghemitization

Published online by Cambridge University Press:  05 July 2018

W. Freer  and
R. O'Reilly
W. Freer
Affiliation:
Department of Geophysics and Planetary Physics, School of Physics, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU
R. O'Reilly*
Affiliation:
Department of Geophysics and Planetary Physics, School of Physics, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU
*
* Present address:, Grant Institute of Geology, University of Edinburgh, West Mains Road Edinburgh EH9 3JW.
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Summary

The maghemitization process, by which magnetic minerals with spinel structure become progressively oxidized but remain single phase spinels, seems to be an important feature of submarine weathering. Whether the process takes place by the minerals acquiring oxygen from the sea-water or by the sea-water leaching out iron, the controlling process is the diffusion of Fe2+ in the spinel structure. Magnetic studies have suggested that during maghemitization the availability for oxidation of Fe2+ in the tetrahedral (A) sites of the spinel structure is much less than that in octahedral (B) sites. In this study the Fe2+-containing spinels FeAl2O4, FeCr2O4, FeGa2O4, and Fe2GeO4, in which Fe2+ is predominantly in either A or B sites were prepared, and the diffusion of Fe2+ was studied by (1) interdiffusion experiments with the Mg2+ counterparts and (2) oxidation experiments in air. Fe2GeO4 (Fe2+ in B sites) was found to be associated with a higher interdiffusion coefficient and lower activation energy than FeAl2O4 (75% Fe2+ in A sites). Oxidation/diffusion activation energies of 0.27 and 0.71 eV were assigned to Fe2+ in B and A sites respectively. The experiments thus provide support for the maghemitization model in which Fe2+ in B sites is preferentially oxidized.

Type
Research Article
Information
Mineralogical Magazine , Volume 43 , Issue 331 , September 1980 , pp. 889 - 899
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1980

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References

Achar, (B. N. N.), Brindley, (G. W.), and Sharp, (J. H.), 1966. Proc. Int. Clay Conf. (Jerusalem), 1, 67-73.Google Scholar
Basta, (Z.), 1953. Ph.D. thesis, University of Bristol.Google Scholar
Blazek, (A.), 1973. Thermal Analysis. Van Nostrand, London, 286 pp.Google Scholar
Boltzmann, (L.), 1894. Ann. Phys. (Leipzig), 53, 959-64.CrossRefGoogle Scholar
Broido, (A.), 1969. J. Polym. Sci. , A2-7, 1761-73.Google Scholar
Buening, (D. K.) and Buseck, (P. R.), 1973. J. Geophys. Res. 78, 6852-62.CrossRefGoogle Scholar
Coats, (A. W.) and Redfern, (J. P.), 1964. Nature, 201, 68-9.CrossRefGoogle Scholar
Buening, (D. K.) Coats, (A. W.) 1965. Polym. Lett. 3, 917-20.Google Scholar
Creer, (K. M.), Ibbetson, (J.), and Drew, (W.), 1970. Geophys. J. R. Astro. Soc. 19, 93-101.CrossRefGoogle Scholar
Dave, (N. G.) and Chopra, (S. K.), 1966. Z. Phys. Chem. (N.F.), 48, 257 66.CrossRefGoogle Scholar
Freeman, (E. S.) and Carroll, (B.), 1958. J. Phys. Chem. 62, 394-7.CrossRefGoogle Scholar
Freer, (R.) and Hauptman, (Z.), 1978. Phys. Earth Planet. Inter. 16, 223-30.CrossRefGoogle Scholar
Fuoss, (R.), Salyer, (I. O.), and Wilson, (H. S.), 1964. J. Polym. Sci. A2, 3147-51.Google Scholar
Grimes, (N. W.), 1972. Phil. Mag. 25, 67-76.CrossRefGoogle Scholar
Hall, (J. M.) and Fischer, (J. F.), 1977. Leg 37, Initial Reports D.S.D.P. 37, 857-73.Google Scholar
Harding, (B. C), 1973. Phys. Stat. Sol. B56, 645-53.CrossRefGoogle Scholar
Irving, (E.), 1970. Can. J. Earth Sci. 7, 1528-38.CrossRefGoogle Scholar
Matano, (C.), 1933. Japan J. Phys. (Trans.), 8, 109-13.Google Scholar
O'Donovan, (J. B.) and O'Reilly, (W.), 1978. Phys. Earth Planet. Inter. 16, 200-8.CrossRefGoogle Scholar
Oishi, (Y.), 1965. J. Chem. Phys. 43, 1611-20.CrossRefGoogle Scholar
O'Reilly, (W.) and Banerjee, (S. K.), 1966. Nature, 211, 26-8.CrossRefGoogle Scholar
Özdemir, (Ö.) and O'Reilly, (W.), 1978. Phys. Earth Planet. Inter. 16, 190-5.CrossRefGoogle Scholar
Ozima, (M), Joshima, (M.), and Kinoshita, (H.), 1974. J. Geomag. Geoelectr. 26, 335-54.CrossRefGoogle Scholar
Petersen, (N.), 1970. Phys. Earth Planet. Inter. 2, 175-8.CrossRefGoogle Scholar
Petherbridge, (J.), Campbell, (A. L.), and Hauptman, (Z.), 1974. Nature, 250, 479-80.CrossRefGoogle Scholar
Rao, (D. B.) and Rigaud, (M.), 1975. Oxid. Metal. 9, 99-116.Google Scholar
Readman, (P. W.), 1972. Ph.D. thesis, University of Newcastle upon Tyne.Google Scholar
Readman, (P. W.) and O'Reilly, (W.), 1970. Phys. Earth Planet. Inter. 4, 121-8.CrossRefGoogle Scholar
Rossiter, (M. J.), 1966. Phys. Lett. 21, 128-30.CrossRefGoogle Scholar
Schwellnus, (C. M.) and Willemse, (J.), 1943. Trans. Geol. Soc. South Africa, 46, 23-38.Google Scholar
Sestak, (J.), 1967. Silikaty, 11, 153-90 (in Czech.).Google Scholar
Sharp, (J. H.), Brindley, (G. W.), and Achar, (B. N. N.), 1966. J. Am. Ceram. Soc. 49, 379-82.CrossRefGoogle Scholar
Stone, (F. S.) and Tilley, (R. J. D.), 1972. In Anderson, (J. S.), Roberts, (M. W.), and Stone, (F. S.) (eds.), Proceedings of the Jth International Conference on the Reactivity of Solids, Chapman & Hall, London, 262-72.Google Scholar
Wilkinson, (R. W.), 1961. Chem. Ind. 1395-7.Google Scholar