Structure of Na2O–MgO–CaO–SiO2 glasses by combined Raman spectroscopy and thermodynamic modeling approach

The present contribution deals with the Raman spectra and structure of Na2O–MgO–CaO–SiO2 glasses. Six glasses with the trisilicate overall composition 15Na2O·xMgO·(10–x)CaO·75SiO2 (x = 0, 2, 4, 6, 8, 10) were studied. The structure of studied glasses was described by the thermodynamic model of Shakhmatkin and Vedishcheva. From the 27 components with the stoichiometry given by the composition of stable crystalline phases, only eight were found in significant abundance in the studied glasses—namely: SiO2, 2MgO·SiO2 (M2S), MgO·SiO2 (MS), Na2O·3CaO·6SiO2 (NC3S6), Na2O·CaO·5SiO2 (NCS5), Na2O·MgO·4SiO2 (NMS4), Na2O·SiO2 (NS), and Na2O·2SiO2 (NS2). The correlation analysis points out that the strong positive correlations between the equilibrium molar amounts of: {M2S–MS–SiO2}, {NC3S6–NCS5}, and {NMS4–NS–NS2}. From the components of significant abundance, only the content of MS and NC3S6 change significantly within the studied compositional series. These two components were identified with the result of the principal component analysis of Raman spectra that indicated the presence of two independent spectral components. Using the method of Malfait the partial Raman spectra of MS and NC3S6 components were found. The obtained results very well reproduce the experimental Raman spectra and confirmed in such way the thermodynamic model.