Quantitative studies on the structure of xCaO⋅(1-x)SiO2 glasses and melts by in-situ Raman spectroscopy, 29Si MAS NMR and quantum chemistry ab initio calculation

ABSTRACT The quantitative distribution of different Qi species in binary calcium silicate glasses and their melts has been investigated by in-situ high temperature Raman spectroscopy, 29Si MAS NMR and quantum chemistry (QC) ab initio calculations. The structural units and several cluster structure models have been designed, optimized and calculated by ab initio calculations. The attribution of their vibrational modes, vibrational wavenumbers of non-bridging silicon-oxygen (Si-Onb) and Raman scattering cross sections (SCS) have then been worked out and analyzed. The functional relationship between the SCS and stress index of silicon-oxygen tetrahedron (SIT) was established for the model clusters of delicate Qi. Quantitative distributions of Qi in calcium silicate glasses and melts are finally obtained which are in good agreement with the experimental results of 29Si MAS NMR. Although the primary structure present in calcium silicate glasses and melts is the same, the relative distribution of Qi is different. On the basis of the present work, it will be helpful to predict the physicochemical properties of silicate slag.