A Raman study of concentrated ethanol-LiCl solid solutions

Publisher Website
Google Scholar
Abstract
Raman spectra were measured for ethanol solid solutions of LiCl of various concentrations between 5 and 77 K. With increasing LiCl concentration, the O-H stretching and the intermolecular vibrational bands changed abruptly from broad bands to sharp peaks at a mole ratio n approximately=8 of EtOH to LiCl. This spectral change is explained by a phase transition from glass to a crystalline hydrate-like cluster. For the solutions at n<or=8, a marked spectral change was observed, at temperatures around 68 K, in the O-H stretching bands, and was ascribed to a lowering of the symmetry of the crystal structure due to thermal contraction on decreasing temperature. Other solid solutions of alkali halides also showed similar spectral changes with alkali halide concentration, except for methanol solutions, but none of them showed any spectral changes on decreasing temperature. These results imply that crystallization commonly takes place in rapidly cooled concentrated solutions of alkali halides, and that the ethanol solid solution of LiCl has a unique crystal structure which causes the spectral change with temperature.