Vibrational spectra of solid and molten phases of the alkali metal tetrafluoroborates

Abstract

Raman and i.r. spectra of the low temperature (orthorhombic) and high temperature (cubic) solid phases of KBF4, RbBF4 and CsBF4 have been measured, and Raman spectra of the molten salts (including LiBF4) have been observed. Studies of the low temperature phase include a determination of the longitudinal optical mode frequencies of the ν3 mode by polarized specular reflectance i.r. spectroscopy. The frequency shift observed for the Raman active component of ν1 in crystalline lithium, sodium, potassium, rubidium, and cesium fluoroborates is interpreted in terms of a model based on an isolated BF4- ion contained in a static field. © 1975.