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Materials science

Measures of crystal vacancies

Nature volume 397, pages 656–657 (1999)Cite this article

It is 73 years since Frenkel1 suggested that some atoms in a crystal will spontaneously leave their lattice sites so that a proportion of vacant lattice sites, or vacancies, remain in equilibrium. That notion, for the first time, explained how matter can be transported in a crystalline solid, because neighbouring atoms can drop into a vacancy, which thus itself migrates. Ever since then, crystal vacancies have been central to solid-state physics, metallurgy and, eventually, materials science. A methodological innovation in the study of such vacancies now comes from Schaefer et al.2, writing in Physical Review Letters. They show how the time variation of vacancy concentration in a crystal can be experimentally determined at varying temperatures. There is currently great interest in the effects of large vacancy concentrations on the mechanical properties of the alloys FeAl and NiAl, and the new technique offers a powerful method of investigating these phenomena.

The first measurements of point-defect concentrations go back to 1943, when Stern (a German refugee in the United States) developed an ultraprecise liquid column with a slight density gradient: ionic crystals were floated in the column and came to rest at a location depending on their density. When such a crystal had been irradiated to generate ‘F-centres’ (a topic of intense interest at that time), a change of density of one part in 104 could be accurately measured, and so the identity of F-centres as associated with vacancies at last became clear. This work was not published3 until 1949; in the meantime, Stern had gained a Nobel prize.

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Figure 1: The experimental approach employed by Schaefer et al.2.

References

  1. Frenkel, J. Z. Physik 35, 652–669 (1926).

    Google Scholar 

  2. Schaefer, H.-E., Frenner, K. & Würschum, R. Phys. Rev. Lett. 82, 948–951 (1999).

    Google Scholar 

  3. Estermann, J., Leivo, W. J. & Stern, O. Phys. Rev. 75, 627–633 (1949).

    Google Scholar 

  4. Feder, R. & Nowick, A. S. Phys. Rev. 109, 1959–1963 (1958).

    Google Scholar 

  5. Nowick, A. S. Annu. Rev. Mater. Sci. 26, 1–19 (1996).

    Google Scholar 

  6. Simmons, R. O. & Balluffi, R. W. Phys. Rev. 119, 600–605 (1960); 125, 862-872 (1962.)

    Google Scholar 

  7. Feder, R. & Charbnau, H. Phys. Rev. 149, 464–471 (1966).

    Google Scholar 

  8. Wollenberger, H. J. in Physical Metallurgy,4th edn (eds Cahn, R. W. & Haasen, P.) 1633 (North-Holland, Amsterdam, 1996).

  9. Turnbull, D., Rosenbaum H. S. & Treaftis, H. N. Acta Metall. 8, 277–295 (1960).

    Google Scholar 

  10. Wolff, J. et al. Intermetallics (in the press).

  11. Chang, Y. A. et al. Intermetallics 1, 107–115 (1993).

    Google Scholar 

  12. George, E. P. & Baker, I. Intermetallics 6, 759–763 (1998).

    Google Scholar 

Download references

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  1. the Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, CB2 3QZ, Cambridge, UK

    Robert W. Cahn

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  1. Robert W. Cahn
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Cahn, R. Measures of crystal vacancies. Nature 397, 656–657 (1999). https://doi.org/10.1038/17701

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