Thermodynamic model and Raman spectra of CaO–P2O5 glasses

Abstract

Raman spectra of xZnO (100−x)P2O5 (x = 35, 40, 45, 50, 55) glasses were described by the thermodynamic model of Shakhmatkin and Vedishcheva using the method of Malfait. The glasses were considered as the ideal solution of unreacted oxides and four compounds (ZnP2O6, Zn2P2O7, Zn3P2O8, and ZnP2O11). Due to missing thermodynamic data, thermodynamic model was based on the estimates of reaction Gibbs energies of formation of considered compounds obtained by fitting the 31P MAS NMR Q-distribution in ZnO–MoO3–P2O5 glasses. Simultaneously, the set of Raman spectra was analyzed by multivariate curve resolution method. The very good coincidence between the results of spectral decomposition based on the thermodynamic model on one side and on the results of MCR method on the other can be considered as plausible validation of the thermodynamic data used, i.e., as a general guideline for the situations where the thermodynamic data needed for the construction of Shakhmatkin and Vedishcheva thermodynamic model are missing but the detailed structural information is available.