Advertisement

Atomic Volume Contraction in Rare Earth Nickel Intermetallics as a Function of Partial Coordination Number Coefficient

  • Forrest L. Carter

Abstract

Molecular volume contraction upon formation of rare earth inter-metallic compounds from the elements is a very well-known phenomenon. While a method for calculating intermetallic atomic volumes was introduced by the author in 1971 as a partial argument for predicting the unstability of SmCo5 (1) and again in 1974 in the discussion of the Pu2C3 structure (2), systematic studies have only recently included rare earth semimetals and intermetallics (3, 4). As might be expected from their large size it is the rare earth atoms that are primarily responsible for the volume contraction. The rare earth atom volume is found herein to decrease approximately linearly with respect to its coefficient of partial coordination number with nickel. This latter concept is a measure of the relative importance and number of rare earth-nickel bonds and arises from the generalization of the concept of coordination number (3, 5). The amount of the rare earth volume contraction is surprisingly large, i.e., greater than 30%. Nickel on the other hand shows a smaller volume expansion upon alloying. These volume changes are thought to be due primarily to size difference effects upon bonding density distribution.

Keywords

Rare Earth Voronoi Cell Volume Contraction Neutral Cell Metallic Radius 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    F. L. Carter, Proc. 9th Rare Earth Res. Conf., ed., D. E. Field, Blacksburg, Va., Vol. 2 (Oct 1971 ) 617.Google Scholar
  2. 2.
    F. L. Carter, T. L. Francavilla, and R. A. Hein, Proc. 11th Rare Earth Research Conf., eds., J. M. Haschke and H. A. Eick, Traverse City, Michigan, (Oct 1974) 36.Google Scholar
  3. 3.
    F. L. Carter, J. Less-Common Metals, 47, 157 (1976).CrossRefGoogle Scholar
  4. 4.
    F. L. Carter, J. Physique Colloque, 40, C5–216 (1979).Google Scholar
  5. 5.
    F. L. Carter, Acta Cryst., B34, 2962 (1978).CrossRefGoogle Scholar
  6. 6.
    G. Voronoi, J Reine und Angew. Math., 134, 198 (1908).CrossRefGoogle Scholar
  7. 7.
    L. Pauling, “Nature of the Chemical Bond,” 3rd ed. (Cornell Univ. Press, Ithaca, New York, 1960), 398 ff.Google Scholar
  8. 8.
    F. L. Carter, Proc. 10th Rare Earth Res. Conf., Carefree, Ariz. (April 1973) 1044.Google Scholar
  9. 9.
    P. Fischer, W. Halg, L. Schlapbach and K. Yvon, J. Less-Common Metals, 60, 1 (1978).CrossRefGoogle Scholar
  10. 10.
    J. H. N. Van Vucht and K. H. J. Buschow, J. Less-Common Metals, 46, 133 (1976).CrossRefGoogle Scholar
  11. 11.
    K. H. J. Buschow and A. S. Van DerGoot, J. Less-Common Metals, 22, 419 (1970).CrossRefGoogle Scholar
  12. 12.
    R. B. Roof, Jr., A. C. Larson, and D. T. Cromer, Acta Cryst., 14, 1084 (1961).CrossRefGoogle Scholar
  13. 13.
    W. B. Pearson, “A Handbook of Lattice Spacings and Structures of Metals and Alloys,” Vol. 2, ( Pergamon Press Ltd., Oxford, London. 1967 ).Google Scholar
  14. 14.
    D. T. Cromer and C. E. Olsen, Acta Cryst., 12, 689 (1959).CrossRefGoogle Scholar
  15. 15.
    D. T. Cromer and A. C. Larson, Acta Cryst. 12, 855 (1959).CrossRefGoogle Scholar
  16. 16.
    A. E. Dwight, R. A. Conner, Jr., and J. W. Downey, Acta Cryst., 18, 837 (1965).CrossRefGoogle Scholar
  17. 17.
    N. C. Baenziger and J. L. Moriarty, Jr., Acta Cryst., 14, 946 (1961).CrossRefGoogle Scholar
  18. 18.
    R. Lemaire and D. Paccard, Bull. Soc. Fr. Miner. Crist., 90, 311–315 (1967).Google Scholar
  19. 19.
    J. M. Moreau, D. Paccard, and E. Parthe, Acta Cryst., B30, 2583 (1974).CrossRefGoogle Scholar
  20. 20.
    J. M. Moreau, D. Paccard, and D. Gignoux, Acta Cryst., B30, 2122 (1974).CrossRefGoogle Scholar
  21. 21.
    A. E. Dwight, Acta Cryst., B24, 1395 (1968).CrossRefGoogle Scholar
  22. 22.
    J. C. Barrick and W. J. James, abstract, Acta Cryst., A31, S96, Part 5 (1975).Google Scholar
  23. 23.
    K. H. J. Buschow, J. Less-Common Metals, 26, 329 (1972).CrossRefGoogle Scholar

Copyright information

© Plenum Press, New York 1980

Authors and Affiliations

  • Forrest L. Carter
    • 1
  1. 1.Chemistry DivisionNaval Research LaboratoryUSA

Personalised recommendations