Structure of zinc halide based glasses

Abstract

Zinc halide based glasses typically contain ⪖ 40 mol % of ZnCl2 or ZnBr2 plus one or more modifying alkali halides such as KBr or KI. These glasses have a considerable degree of covalence and their structure may be somewhat analogous to that of modified silicate glasses. A series of binary glasses was prepared by melting in sealed pyrex ampoules and their polarized Raman spectra were recorded in situ. The spectral response was interpreted, with the aid of compositional variations, by means of a vibrational model including three different force constants. The short and intermediate range structures of these glasses are discussed and compared to oxide glass models. In compositions with 50 mol % of network-forming halide, a chain structure appears to be favored, similar to that of a metasilicate glass. For different stoichiometries, either two-dimensional or dimer-like structures may be present, depending on the concentration of the network former.