Hostname: page-component-586b7cd67f-t7fkt Total loading time: 0 Render date: 2024-11-28T03:20:33.801Z Has data issue: false hasContentIssue false
  • English
  • Français

Cation and vacancy distribution in an artificially oxidized natural spinel

Published online by Cambridge University Press:  05 July 2018

Giorgio Menegazzo ,
Susanna Carbonin  and
Antonio Della Giusta
Giorgio Menegazzo
Affiliation:
Liceo Scientifico I. Nievo, Padova, Via Barbarigo 38, 35141 Padova, Italy
Susanna Carbonin
Affiliation:
Dipartimento di Mineralogia e Petrologia, Università di Padova, Corso Garibaldi 37, 35122 Padova, Italy
Antonio Della Giusta
Affiliation:
Dipartimento di Mineralogia e Petrologia, Università di Padova, Corso Garibaldi 37, 35122 Padova, Italy
Get access Rights & Permissions [Opens in a new window]

Abstract

During research on the influence of temperature on cation partitioning in natural Mg-Al-Fe2+-Fe3+ spinels, some crystals were accidentally oxidized during heat treatment. The oxidation product, studied by means of single-crystal X-ray diffraction, turned out to be a phase retaining the Fd3m parent spinel structure, but with cell edge a and oxygen coordinate u considerably smaller than the parent ones (a ∼ 8.087 as compared with ∼ 8.111 Å; u ∼ 0.2609 vs. 0.2617–0.2636) and with vacant sites due to oxidation.

Assuming that the oxidation process must occur due to the addition of oxygen to the crystal boundary as cations are being preserved and rising in total valence, the site population was determined and compared with that of untreated and heated samples. It was found that, on oxidation, a charge enrichment in the tetrahedral site T had occurred, this phenomenon following that observed during heating at increasing temperatures also in other spinel series. This continuity was always in the direction of an increase in random charge distribution. Cation vacancies produced during oxidation were restricted to the octahedral site M.

Examination of bulk sections by reflected light microscopy showed a few hematite lamellae as inclusions in the oxidized samples, not detectable by microprobe analysis or single-crystal structural refinement. However, hematite played a marginal part in oxidation. Vacancy-oxygen distances in oxidized spinels were determined from experimental data in the literature.

Keywords

spineloxidationvacanciessite population
Type
Mineralogy
Information
Mineralogical Magazine , Volume 61 , Issue 406 , June 1997 , pp. 411 - 421
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1997

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Basso, R., Carbonin, S. and Della Giusta, A. (1991) Cation and vacancy distribution in a synthetic defect spinel. Zeit. Kristallogr., 194, 111-9.CrossRefGoogle Scholar
Blessing, R.H., Coppens, P. and Becker, P. (1972) Computer analysis of step-scanned X-ray data. J.. Appl. Crystallogr., 7, 488-92.CrossRefGoogle Scholar
Carbonin, S., Russo, U. and Della Giusta, A. (1996) Cation distribution in some natural spinels from Xray diffraction and Mössbauer spectroscopy.. Mineral. Mag., 60, 355-68.CrossRefGoogle Scholar
Clegg, W. (1981) Faster data collection without loss of precision. An extension of the learnt profile method. Acta Crystallogr., A37, 22–28.CrossRefGoogle Scholar
Colombo, U., Fagherazzi, G., Gazzarrini, F., Lanzavecchia, G. and Sironi, G. (1964a) Studio sull'ossidazione delle magnetiti. Chimica e Industria 46, 357-62.Google Scholar
Colombo, U., Fagherazzi, G., Gazzarrini, F., Lanzavecchia, G. and Sironi, G. (1964b) Mechanisms in the first stage of oxidation of magnetites. Nature 202, 175-6.CrossRefGoogle Scholar
Comin-Chiaramonti, P., Demarchi, G., Siena, F. and Sinigoi, S. (1982) Relazioni tra fusione e deformazione nella peridotite di Balmuccia (lvrea-Verbano).. Rend. Soc. ltal. Mineral. Petrol. 38, 685–700.Google Scholar
Davis, B.L., Rapp, G.Jr. and Walawender, M.J. (1968) Fabric and structural characteristics of the martitization process. Amer. J. Sci., 266, 482-96.CrossRefGoogle Scholar
Della Giusta, A., Carbonin, S. and Ottonello, G. (1996) Temperature-dependent disorder in a natural Mg-A1-Fe2+-Fe3+-spinel. Mineral. Mag., 60, 603-16.CrossRefGoogle Scholar
Feitknecht, W. and Gallagher, K.J. (1970) Mechanisms for the oxidation of Fe3O4 . Nature 228, 548-9.CrossRefGoogle ScholarPubMed
Fleet, M.E. and Arima, M. (1985) Oriented hematite inclusions in sillimanite. Amer. Mineral., 70, 1232-7.Google Scholar
Guse, W. and Saalfeld, H. (1990) X-ray characterization and structure refinement of a new cubic alumina phase (σ-Al2O3) with spinel-type structure. Neues Jahrb. Mineral., Mh., 217-26.Google Scholar
Hill, R.J., Craig, J.R. and Gibbs, G.V. (1979) Systematics of the spinel structure type. Phys. Chem. Minerals, 4, 317-39.CrossRefGoogle Scholar
James, F. and Roos, M. (1975) MINUIT. A system for function minimization and analysis of the parameters errors and correlations. Comp. Phys. Comm., 10, 343-67.CrossRefGoogle Scholar
Kullerud, G., Donnay, G. and Donnay, J.D.H. (1969) Omission solid solution in magnetite: Kenotetrahedral magnetite. Zeit. Kristallogr., 128, 1–17. CrossRefGoogle Scholar
Larsson, L., O'Neill, H.St.C. and Annersten, H. (1994) Crystal chemistry of synthetic hercynite (FeAl2O4) from XRD structural refinements and Mössbauer spectroscopy. Eur. J. Mineral., 6, 39-51.CrossRefGoogle Scholar
Lucchesi, S. and Della Giusta, A. (1994) Crystal chemistry of non-stoichiometric Mg-A1 synthetic spinels. Zeit. Kristallogr. 209, 714-9.Google Scholar
Navrotsky, A. and Kleppa, O.J. (1967) The thermodynamics of cation distribution in simple spinels. J.. lnorg. Nucl. Chemistry 29, 2701-14.CrossRefGoogle Scholar
Navrotsky, A., Wechsler, B.A., Geisinger, K. and Seifert, F. (1986) Thermochemistry of MgAl2O4-Al8/3O4 defect spinels. J. Amer. Ceramic Soc., 69, 418-22.CrossRefGoogle Scholar
North, A.C.T., Phillips, D.C. and Scott-Mattews, F. (1968) A semi-empirical method of absorption correction, Acta Crystallogr., A24, 351-2.CrossRefGoogle Scholar
O'Neill, H.St.C., Dollase, W.A. and Ross, C.R.II (1991) Temperature dependence of the cation distribution in Nickel Aluminate (NiAl2O4) spinel: a powder XRD study. Phys. Chem. Minerals 18, 302-19.CrossRefGoogle Scholar
O'Neill, H.St.C., Annersten, H. and Virgo, D. (1992) The temperature dependence of the cation distribution in magnesioferrite (MgFe2O4) from powder XRD structural refinements and Mössbauer spectroscopy. Amer. Mineral., 77, 725-40.Google Scholar
O'Reilly, W. and Banerjee, S.K. (1967) The mechanism of oxidation in titanomagnetites: a magnetic study.. Mineral. Mag. 36, 29-37.Google Scholar
Pizzolon, M. (1991) Cristallochimica e modellizzazione di spinelli di Mg-AI-Fe-Cr. Thesis, University of Padova, Padova, Italy.Google Scholar
Princivalle, F., Della Giusta, A. and Carbonin, S. (1989) Comparative crystal chemistry of spinels from some suites of ultramafic rocks. Mineral. Petrol., 40, 117-26.CrossRefGoogle Scholar
Roelofsen, J.N., Peterson, R.C. and Raudsepp, M. (1992) Structural variation in nickel aluminate spinel (NiAl2O4). Amer. Mineral., 77, 522-8.Google Scholar
Sheldrick, G.M. (1993) SHELX- 93. Program for crystal structure refinement. University of Göttingen, Germany.Google Scholar
Viertel, H.U. and Seifert, F. (1979) Physical properties of defect spinels in the system MgAl2O4-Al2O3.. Neues Jahrb. Mineral., Abh. 134, 167-82.Google Scholar
Waerenborgh, J.C., Figuereido, M.O., Cabral, J.M.P. and Pereira, L.C.J. (1994) Powder XRD structure refinements and 57Fe MOssbauer effect study of synthetic Zn1-xFexAl2O4 (0< x ≤1) spinels annealed at different temperatures. Phys. Chem. Minerals 21, 460-8.CrossRefGoogle Scholar