Raman Spectroscopy and Statistical Analysis of the Silicate Species and Group Connectivity in Cesium Silicate Glass Forming System

Abstract

The Raman spectra of x %Cs 2 O-(100 − x )%SiO 2 ( x = 17 , 22, 27, 33, and 37 mol%) glasses and melts were measured in the temperature range of 293 to 1553 K. The concentrations of the Q n species were calculated as a function of the composition and temperature based on the deconvolution analysis of the spectra. It was found that a dynamic equilibrium among structural units in the melts with x > 17 mol% can be described by disproportionation reaction Q 3 ⇔ Q 4 + Q 2 . The enthalpy of this reaction was found to be equal to 32 ± 6, 43 ± 8, 56 ± 10, and 52 ± 9 for x = 22 , 27, 33, and 37 mol%, respectively. The nonideal entropy of mixing (Δ S mix ) depends on the melt temperature and increases almost linearly with increasing temperature. The Q n , Q 2 – Q 2 , and Q n , i j k l distributions with x ranging from 0 to 55 mol% were modeled using experimental data for the concentrations of the Q n units.