Journal of Materials Science

, Volume 18, Issue 1, pp 195–207 | Cite as

Mössbauer, EXAFS, and X-ray diffraction study of Fe3+ clusters in MgO:Fe and magnesiowüstite (Mg,Fe)1−xO-evidence for specific cluster geometries

  • Glenn A. Waychunas


Mössbauer and EXAFS analysis of Fe3+-doped MgO rapidly quenched from 1200° C have yielded octahedral/tetrahedral Fe3+ site occupancy ratios which are used to place constraints on the possible defect cluster geometries. The data suggest the samples contain a range of defect aggregates consisting of combinations of basic dimer and trimer units (octahedral Fe3+ ions coupled to 1 or 2 cation vacancies) and variations about the “4-1” cluster motif. (Four cation vacancies surrounding one interstitial Fe3+.) The groupings are consistent with lattice-energy calculations for defect clusters in both FeO and MgO, the observed sample colour, and prior TEM and ED observations of defect ordering in quenched wüstite. Low-temperature annealing of the samples results in cluster growth and changes in the Mössbauer spectrum attributable to production of magnesioferritelike aggregates. The colour of the samples after annealing is indicative of grouping of magnetically interactive octahedral Fe3+ ions such as would be present in spinel nuclei. X-ray diffraction structure factor measurements of magnesiowüstite with 70 cation % Fe/(Fe+Mg) yield defect-concentration ratios similar to those observed in MgO and wüstite. This indicates that initial clustering of Fe3+ ions and cation vacancies probably results in similar structures throughout the MgO-FeO-Fe2O3 system.


Site Occupancy Cation Vacancy Initial Cluster Sample Colour Defect Cluster 
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  1. 1.
    U. Gonser, R. W. Grant, H. Wiedersich, R. Chang and A. H. Muir, Bull Amer. Phys. Co. 11 (1966) 363.Google Scholar
  2. 2.
    H. R. Leider and D. N. Pipkorn, Phys. Rev. 165 (1968) 494.Google Scholar
  3. 3.
    B. Henderson, J. E. Wertz, T. P. P. Hall and R. D. Dowsing, J. Phys. C4 (1971) 107.Google Scholar
  4. 4.
    R. A. Weeks, J. Gastinequ and E. Sonder, Phys. Stat. Sol. 61A (1980) 265.Google Scholar
  5. 5.
    W. H. Gourdin and W. D. Kingery, J. Mater. Sci. 14 (1979) 2053.Google Scholar
  6. 6.
    T. A. Yager and W. D. Kingery, ibid. 16 (1981) 489.Google Scholar
  7. 7.
    C. R. A. Catlow and B. E. F. Fender, J. Phys. C8 (1975) 3267.Google Scholar
  8. 8.
    G. A. Waychunas, Ph.D. Thesis, University of California, Los Angeles (1979).Google Scholar
  9. 9.
    T. A. Finnerty, G. A. Waychunas and W. M. Thomas, Amer. Mineral. 63 (1978) 415.Google Scholar
  10. 10.
    E. Kankeleit, Rev, Sci. Instrum. 35 (1964) 194.Google Scholar
  11. 11.
    S. J. H. Hunter, Ph.D. Thesis, Stanford University (1977).Google Scholar
  12. 12.
    G. S. Brown and S. Doniach, “Synchrotron Radiation Research” (Plenum, New York, 1980) Ch. 10, p. 353.Google Scholar
  13. 13.
    S. P. Cramer, K. O. Hodgson, E. I. Stiefil and W. E. Newton, J. Amer. Chem. Soc. 100 (1978) 2748.Google Scholar
  14. 14.
    G. H. Via, J. H. Sinfelt and F. W. Lytle, Chem. Phys. 71 (1979) 690.Google Scholar
  15. 15.
    R. D. Shannon and C. T. Prewitt, Acta Cryst. B25 (1969) 925.Google Scholar
  16. 16.
    I. D. Brown and R. D. Shannon, ibid. A29 (1973) 266.Google Scholar
  17. 17.
    R. G. Shulman, Y. Yafet, P. Eisenberger and W. E. Blumberg, Proc. Nat. Acad. Sci. USA 73 (1975) 1384.Google Scholar
  18. 18.
    G. A. Waychunas, M. J. Apted and G. E. Brown, Phys. Chem. Miner. submitted.Google Scholar
  19. 19.
    H. H. Wickman, Mössbauer Effect Methodology 2 (1966) 39.Google Scholar
  20. 20.
    E. De Grave, A. Govaert, D. Chambaere and G. Robbrecht, Physica 96B (1979) 103.Google Scholar
  21. 21.
    G. A. Sawatzky, F. Van Der Woude and A. H. Morrish, Phys. Rev. 183 (1969) 383.Google Scholar
  22. 22.
    R. Ingalls, ibid. 122 (1964) A787.Google Scholar
  23. 23.
    S. L. Ruby, Mössbauer Effect Methodology 8 (1973) 263.Google Scholar
  24. 24.
    G. R. Rossman, personal communication (1980).Google Scholar
  25. 25.
    Idem, Amer. Mineral. 60 (1975) 698.Google Scholar
  26. 26.
    W. Kundig, H. Bommel, G. Constabaris and R. H. Lindquist, Phys. Rev. 142 (1966) 327.Google Scholar
  27. 27.
    C. J. Kriesman and S. E. Harrison, ibid. 103 (1956) 857.Google Scholar
  28. 28.
    R. Pauthenet and L. Bochirol, J. Phys. Radium 12 (1951) 249.Google Scholar
  29. 29.
    B. Anderson and J. O. Sletnes, ibid. A33 (1977) 268.Google Scholar
  30. 30.
    F. Koch and J. B. Cohen, Acta Cryst. B25 (1969) 275.Google Scholar
  31. 31.
    A. K. Cheetham, B. E. F. Fender and R. I. Taylor, J.Phys. C4 (1971) 2160.Google Scholar

Copyright information

© Chapman and Hall Ltd. 1983

Authors and Affiliations

  • Glenn A. Waychunas
    • 1
  1. 1.Center for Materials ResearchStanford UniversityStanfordUSA

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