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Anharmonicity of Infrared Vibration Modes in the Nesosilicate Be 2 SiO 4
Author(s) -
Gervais F.,
Piriou B.,
Cabannes F.
Publication year - 1973
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220550114
Subject(s) - anharmonicity , quartic function , vibration , infrared , tetrahedron , infrared spectroscopy , phonon , condensed matter physics , normal mode , molecular physics , materials science , molecular vibration , dispersion (optics) , atmospheric temperature range , tetrahedral symmetry , chemistry , physics , optics , quantum mechanics , thermodynamics , rotational symmetry , crystallography , mathematics , raman spectroscopy , mechanics , pure mathematics
The anharmonicity of the infrared vibration modes in phenacite Be 2 SiO 4 has been studied by measurements of the temperature dependence of the reflectivity from 270 to 1500 cm −1 . The spectra obtained in the temperature range 300 to 1500 K have been analysed by the classical dispersion theory. The cubic and quartic contributions to the anharmonicity of most of the observed modes were evaluated. From the observed dependence of mode damping on temperature and by comparison with the site symmetry method results nearly all modes have been assigned as external or internal to the tetrahedron SiO 4 . It is found that the cubic terms cause the anharmonicity of the internal modes, whereas both cubic and quartic terms contribute to that of the external modes.