Raman spectroscopic study of phase transformation in single crystals of cadmium fluorosilicate hexahydrate

Abstract

A detailed temperature-dependent Raman study of oriented single crystals of CdSiF, 6H,O down to 10 K was made in the region of internal vibrations and lattice modes. The frequency shifts, linewidths and intensities of some of the modes associated with the [Cd(OH,),]2+ and (SiF,)'-ions show abrupt changes at temperatures around 220 K and some doubly degenerate modes split into two components. These studies suggest that the system undergoes a structural phase transition at ca. 220 K.