Soft vibrational mode in LiNbO3 and LiTaO3 |
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| Authors: | JL Servoin F Gervais |
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| Institution: | Centre de Recherches sur la Physique des Hautes Températures, Centre National de la Recherche Scientifique, and UER Sciences Fondamentales et Appliquées, Université d''Orléans, 45045 Orléans, France |
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| Abstract: | The temperature dependence of the far-infrared reflectivity as obtained with a scanning interferometer for the A1- and E-type modes of both LiNbO3 and LiTaO3 is reported in the ferroelectric phase. Results of a Kramers-Kronig analysis are compared with Raman and neutron scattering data which are controversial about the existence of a soft vibrational mode. For LiTaO3, spectra are obtained 300 K above the Curie temperature, in the paraelectric phase. The lowest-frequency A1 (TO) mode is unambiguously found as soft and becomes rapidly overdamped. |
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