Raman spectra of Ba2NaNb5O15

Abstract
The Raman spectra of Ba2NaNb5O15 single crystals were recorded for various scattering configurations from 77°K to 843°K. Splittings of the vibrational modes due to electrostatic and anisotropic forces were found to be small. The line-widths of the 650 cm-1 and the 280 cm-1 modes were found to increase with increasing temperature. The 'soft' A1(z) mode at 723°K was fitted by means of a graphical interpolation to an overdamped lineshape with an undamped mode frequency of 40 cm-1 and a damping constant of 2.