Anharmonicity of Infrared Vibration Modes in the Nesosilicate Be2SiO4

✍ Scribed by F. Gervais; B. Piriou; F. Cabannes

• Publisher: John Wiley and Sons
• Year: 1973
• Tongue: English
• Weight: 566 KB
• Volume: 55
• Category: Article
• ISSN: 0370-1972
• DOI: 10.1002/pssb.2220550114

✦ Synopsis

Abstract

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.