High Pressure Studies of Soft Mode Transitions in Solids

  • G. A. Samara

Abstract

An overview of the soft mode concept and of high pressure studies of soft; mode transitions in solids is given. Typical results on dis-placive ferroelectric (SbSI) antiferrodistortive [Gd2(MoO4)3 and BaMnF4] transitions as well as on coupled proton-phonon soft mode transitions (KH2PO4) are used to demonstrate that hydrostatic pressure can strongly modify the balance of forces responsible for soft mode behavior. Emphasis is placed on the physical implications of the results and on the general trends of the available data on the different classes of soft mode transitions, for it is such trends that have led to a greater understanding of the nature of the forces involved.

Keywords

Sodium Chloride Fluoride Barium Perovskite Rutile 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    W. Cochran, Adv. Phys. 9, 387 (1960).CrossRefGoogle Scholar
  2. 2.
    P.W. Anderson, in Fizika Dielektrekova (G.I. Shanski, Ed.), Acad. Sci. USSR, Moscow (1960).Google Scholar
  3. 3.
    See, e.g., J.F. Scott, Rev. Mod. Phys. 46, 83 (1974) and references therein.CrossRefGoogle Scholar
  4. 4.
    P.S. Peercy and I.J. Fritz, Phys. Rev. Letters 32, 466 (1974).CrossRefGoogle Scholar
  5. 5.
    G.A. Samara, Proc. 4th International Conference on High Pressure, The Physico-Chemical Soc. Japan, Kyoto (1974) p. 247.Google Scholar
  6. 6.
    E. Pytte, Comments Sol. St. Phys. 5, 41 (1973).Google Scholar
  7. 7.
    R.A. Cowley, Phys. Rev. 134, A981 (1964).CrossRefGoogle Scholar
  8. 8.
    G.A. Samara, T. Sakudo and K. Yoshimitsu, Phys. Rev. Letters 35, 1767 (1975);CrossRefGoogle Scholar
  9. 8a.
    G.A. Samara, Comments Sol. St. Phys. 8, 13 (1977).Google Scholar
  10. 9.
    G.A. Samara, Ferroelectrics 9, 209 (1975).CrossRefGoogle Scholar
  11. 10.
    See e.g., D.K. Agrawal and C.H. Perry, Phys. Rev. B 4, 1893 (1971).CrossRefGoogle Scholar
  12. 11.
    In this paper we use two transition temperatures To and Tc. To is the temperature where the soft mode frequency goes to zero or extrapolates to zero. Tc is the temperature where the structural transition actually takes place. For a second-order transition To and Tc are one and the same temperature.Google Scholar
  13. 12.
    G.A. Samara in Advances in High Pressure Research, R.S. Bradley, Ed. (Academic Press, N.Y., 1969) Vol. 3, Chapt. 3.Google Scholar
  14. 13.
    T.R. Volk, E.I. Gerzanich and V.M. Fridkin, Bull. Acad. Sci. USSR, Phys. Ser. (USA) 33, 319 (1969).Google Scholar
  15. 14.
    P.S. Peercy, Phys. Rev. Letters 35, 1581 (1975).CrossRefGoogle Scholar
  16. 15.
    V.H. Schmidt, A.B. Western and A.G. Baker, Phys. Rev. Letters 37, 839 (1976).CrossRefGoogle Scholar
  17. 16.
    G.A. Samara, Ferroelectrics 2, 277 (1971).CrossRefGoogle Scholar
  18. 17.
    R. Clarke and L. Benguigui, J. Phys. C: Solid State Phys. (to be published).Google Scholar
  19. 18.
    V.H. Schmidt, Proceedings of this Conference.Google Scholar
  20. 19.
    P.S. Peercy, Proceedings of this Conference and references therein.Google Scholar
  21. 20.
    R.P. Lowndes and A. Rastogi, J. Phys. C: Solid State Phys. 6, 932 (1973).CrossRefGoogle Scholar
  22. 21.
    G.A. Samara and B. Morosin, Phys. Rev. B 8, 1256 (1973).CrossRefGoogle Scholar
  23. 22.
    G.A. Samara and P.S. Peercy, Phys. Rev. B 7, 1131 (1973).CrossRefGoogle Scholar
  24. 23.
    G.A. Samara, Phys. Rev. B. 13, 4529 (1976).CrossRefGoogle Scholar
  25. 24.
    We have just recently discovered the evidence for a soft zone center TO phonon in KMnF3.Google Scholar
  26. 25.
    S.S. Kabalkina, N.R. Serebryanaya and L.F. Vereshchagin, Sov. Phys.-Solid State 9, 2527 (1968).Google Scholar
  27. 26.
    See Ref. 8 and G.A. Samara, Comments Sol. St. Phys. 8, 13 (1977).Google Scholar
  28. 27.
    K. Yoshimitsu, Prog. Theor. Phys. 54, 583 (1975).CrossRefGoogle Scholar
  29. 28.
    J.D. Axe, B. Dorner and G. Shirane, Phys. Rev. Letters 26, 519 (1971).CrossRefGoogle Scholar
  30. 29.
    L.E. Cross, A. Fouskova and S.I. Cummins, Phys. Rev. Letters 21, 812 (1968).CrossRefGoogle Scholar
  31. 30.
    A.M. Shirokov, V.M. Mylov, A.I. Baranov and T.M. Prokhortseva, Sov. Phys.-Solid State 13, 2610 (1972).Google Scholar
  32. 31.
    See G.A. Samara and P.M. Richards, Phys. Rev. B 14, 5073 (1976) for references and details.CrossRefGoogle Scholar
  33. 32.
    J.F. Ryan and J.F. Scott, Solid State Commun. 14, 5 (1974).CrossRefGoogle Scholar
  34. 33.
    S.M. Shapiro, R.A. Cowley, D.E. Cox, M. Eibschutz and H.J. Guggenheim, Proc. Conf. on Neutron Scattering, Gatlingburg, Tenn. (1976).Google Scholar
  35. 34.
    W.G. Stirling, J. Phys. C: Solid State Phys. 5, 2711 (1972).CrossRefGoogle Scholar
  36. 35.
    A.D. Bruce and R.A. Cowley, J. Phys. C: Solid State Phys. 6, 2422 (1973).CrossRefGoogle Scholar
  37. 36.
    G.A. Samara, Ferroelectrics 5, 25 (1973).CrossRefGoogle Scholar
  38. 37.
    G.A. Samara, Phys. Rev. Letters 27, 103 (1971).CrossRefGoogle Scholar
  39. 38.
    P.S. Peercy, Phys. Rev. Letters 31, 380 (1973).CrossRefGoogle Scholar
  40. 39.
    R.P. Lowndes, N.E. Tornberg and R.C. Leung, Phys. Rev. B 10, 911 (1974).CrossRefGoogle Scholar
  41. 40.
    P.S. Peercy, Solid State Commun, 16, 439 (1975).CrossRefGoogle Scholar
  42. 41.
    K. Kobayashi, J. Phys. Soc. Japan 24, 497 (1968).CrossRefGoogle Scholar
  43. 42.
    P.S. Peercy and G.A. Samara, Phys. Rev. B 8, 2033 (1973).CrossRefGoogle Scholar
  44. 43.
    The actual transition temperature Tc in KDP differs from To in Eq. 9 by ~ 5 K because of optic-acoustic coupling. This coupling effect can be neglected for the purpose of this discussion.Google Scholar
  45. 44.
    P.S. Peercy, I.J. Fritz and G.A. Samara, J. Phys. Chem. Solids 36, 1105 (1975).CrossRefGoogle Scholar
  46. 45.
    T.G. Worlton and R.A. Beyerlein, Phys. Rev. B 12, 1899 (1975).CrossRefGoogle Scholar
  47. 46.
    I.J. Fritz and P.S. Peercy, Solid State Commun. 16, 1197 0–975).Google Scholar
  48. 47.
    L.R. Testardi, Comments Sol. St. Phys. 6, 131 (1975).Google Scholar
  49. 48.
    C.W. Chu and L.R. Testardi, Phys. Rev. Letters 32, 766 (1974).CrossRefGoogle Scholar
  50. 49.
    C.W. Chu, Phys. Rev. Letters 33, 1283 (1974).CrossRefGoogle Scholar
  51. 50.
    C. W. Chu, Proceedings of this Conference.Google Scholar

Copyright information

© Plenum Press, New York 1978

Authors and Affiliations

  • G. A. Samara
    • 1
  1. 1.Sandia LaboratoriesAlbuquerqueUSA

Personalised recommendations