Hostname: page-component-78c5997874-dh8gc Total loading time: 0 Render date: 2024-10-31T23:44:28.488Z Has data issue: false hasContentIssue false

Phase transitions in mixed disordered crystals Rb1−x Kx CaF3 (0 < x < 1) investigated by Raman spectroscopy

Published online by Cambridge University Press:  15 January 1999

Ph. Daniel
Affiliation:
Laboratoire de Physique de l'État Condensé (UPRES A CNRS 6087), Université du Maine, avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France
J. Toulouse
Affiliation:
Physics Department-Lehigh University 16, Memorial Drive, East PA 18015 Bethlehem, USA
M. Rousseau
Affiliation:
Laboratoire de Physique de l'État Condensé (UPRES A CNRS 6087), Université du Maine, avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France
Get access

Abstract

Structural antiferrodistortive phase transitions have been studied in mixed disordered perovskites Rb1−x Kx CaF3 crystals over a wide concentration range (0 < x < 1) by Raman spectroscopy and a full group theory analysis has been carried out. Raman spectra have been indexed in all phases and a “one mode” behavior is evidenced. The influence of the cationic substitution on the mechanism driving the transitions is characterized by: i) the disappearance of the strong first-ordercharacter of the low temperature transition in RbCaF3; ii) the continuous evolution of the Raman spectra as a function of temperature, with no sharp indication of a transition except for the classical soft mode behavior; iii) the persistence of hard Raman modes even in the ideal cubic phase; iiii) the appearance of a broad central component associated with relaxation processes. Finally, the results of lattice dynamics calculations, when compared to inelastic neutron scattering measurements, show that the classical virtual crystal model fails. These results are examined in terms of a simple displacive transition for these fluoro-perovskites in which the interactions between F6 octahedra are anisotropic and the importance of the substitutional disorder is highlighted.

Keywords

Type
Research Article
Copyright
© EDP Sciences, 1999

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

Barker Jr, A.S.., A.J. Sievers, Rev. Mod. Phys. 47, 1 (1975). CrossRef
Cowley, R.A., Adv. Phys. 29, 1 (1980) and references therein. CrossRef
Bruce, A.D., Adv. Phys. 29, 111 (1980). CrossRef
Bruce, A.D., Cowley, R.A., Adv. Phys. 29, 219 (1980). CrossRef
Modine, F.A., Sonder, E., Unruh, W.P., Finch, C.B., Westbrook, R.D., Phys. Rev. B 10, 1623 (1974). APS Link not valid for this citation CrossRef
Ph. Daniel, M. Rousseau, J. Toulouse, Phys. Rev. B 55, 6222 (1997). CrossRef
Bulou, A., Ridou, C., Rousseau, M., Nouet, J., J. Phys. France 41, 87 (1980). CrossRef
Glazer, A.M., Acta Cryst. A 31, 756 (1975). CrossRef
Bulou, A., Nouet, J., Hewat, A.W., Schäfer, F.J., Ferroelectr. 25, 375 (1980). CrossRef
Hidaka, M., Yamashita, S., Okamoto, Y., Phys. Stat. Sol. (a) 81, 177 (1984). CrossRef
Rousseau, M., Daniel, Ph., Hennion, B., J. Phys. Cond. 9, 8963 (1997). CrossRef
Ph. Daniel, M. Rousseau, J. Toulouse, Phys. Stat. Sol. (b) 203, 327 (1997). 3.0.CO;2-W>CrossRef
Ratuszna, A., Rousseau, M., Daniel, Ph., Powder diffraction 12, 70 (1997). CrossRef
Foucher, P., Buzaré, J.Y., Ridou, C., Rousseau, M., Hennion, B., Ferroelectr. 107, 325 (1990). CrossRef
Ratuszna, A., Daniel, Ph., Rousseau, M., Phase Transitions 54, 43 (1995). CrossRef
Jouanneaux, A., Daniel, Ph., Bushnell-Wye, G., J. Phys. Cond. mat. 10, 5485 (1998). CrossRef
Ph. Daniel, J. Toulouse, M. Rousseau, A Désert, A. Ratuszna, Phil. Mag. B 79, 319 (1999). CrossRef
Hidaka, M., Zhou, Z.Y., Yamashita, S., Phase Transitions 20, 83 (1990). CrossRef
J. Nouet, Soc. Photo-opt. Instrum. Eng. (SPIE), Proceeding Series, 3178 (1997).
J. Toulouse, M. Rousseau, Ph. Daniel, B. Hennion, S.M. Shapiro (to be published).
B. Hennion (private communication).
Rousseau, D.L., Bauman, R.P., Porto, S.P.S., J. Raman Spectr. 10, 253 (1981). CrossRef
Shuker, R., Gammon, R.W., Phys. Rev. Lett. 25, 222 (1970). APS Link not valid for this citation CrossRef
Rousseau, M., J . Nouet, A. Zarembowitch, J. Phys. Chem. 35, 921 (1974).
Salaün, S., Rousseau, M., Phys. Rev. B 51, 15867 (1995). CrossRef
Idriss-Bey, K., Foucher, P., Buzaré, J.Y., Nouet, J., Ridou, C., Rousseau, M., Hennion, B., Simon, P., Ferroelectr. 107, 319 (1990). CrossRef
Rousseau, M., Nouet, J., Almairac, R., J. Phys. France 38, 1423 (1977). CrossRef
Langer, J.S., J. Math. Phys. 2, 584 (1961). CrossRef
Shen, Y.S., Shockley, W., Pearson, G.L., Phys. Rev. 151, 648 (1966).
Rushworth, A.J., Ryan, J.F., Solid St. Commun. 18, 1239 (1976). CrossRef
Ridou, C., Rousseau, M., Gesland, J.Y., Nouet, J., Zarembowitch, A., Ferroelectr. 12, 199 (1976). CrossRef
Ridou, C., Rousseau, M., Bouillot, J., Ferroelectr. 36, 463 (1981). CrossRef
Bruce, A.D., Taylor, W., Murray, A.F., J. Phys. C 13, 483 (1980). CrossRef
Yacoby, Y., Stern, E.A., Comments Cond. Mat. Phys. 18, 1 (1996)
Rousseau, M., Daniel, Ph., Toulouse, J., Hennion, B., Physica B 234-236, 139 (1997). CrossRef
Kerr, W.C., Bishop, A.R., Phys. Rev. B 34, 6295 (1986). CrossRef
Bulou, A., Rousseau, M., Nouet, J., Ferroelectr. 104, 373 (1991). CrossRef
Ph. Daniel, M. Rousseau, J. Toulouse, B. Hennion (to be published).