| Автор | Daniel, Ph. |
| Автор | Toulouse, J. |
| Автор | Rousseau, M. |
| Дата выпуска | 1999 |
| dc.description | Structural antiferrodistortive phase transitions have been studied in mixed disordered perovskites Rb<sub>1−x </sub>K<sub> x </sub>CaF<sub>3</sub> 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-order character of the low temperature transition in RbCaF<sub>3</sub>; 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 F<sub>6</sub> octahedra are anisotropic and the importance of the substitutional disorder is highlighted. |
| Формат | application.pdf |
| Издатель | EDP Sciences |
| Копирайт | © EDP Sciences, 1999 |
| Название | Phase transitions in mixed disordered crystals Rb<sub>1−x </sub>K<sub> x </sub>CaF<sub>3</sub> (0 < x < 1) investigated by Raman spectroscopy |
| Тип | research-article |
| DOI | 10.1051/epjap:1999109 |
| Electronic ISSN | 1286-0050 |
| Print ISSN | 1286-0042 |
| Журнал | The European Physical Journal Applied Physics |
| Том | 5 |
| Первая страница | 33 |
| Последняя страница | 44 |
| Аффилиация | Daniel Ph.; Laboratoire de Physique de l'État Condensé (UPRES A CNRS 6087), Université du Maine, avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France |
| Аффилиация | Toulouse J.; Physics Department-Lehigh University 16, Memorial Drive, East PA 18015 Bethlehem, USA |
| Аффилиация | Rousseau M.; Laboratoire de Physique de l'État Condensé (UPRES A CNRS 6087), Université du Maine, avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France |
| Выпуск | 1 |
