Melts and glasses of the K2O-GeO2 system: Physicochemical modelling with correction based on the results of Raman spectroscopy

A Gibbs free energy minimization approach realized in “Selector-C” software is used to study germanate melts and glasses of the K2O–GeO2 system. A database of the thermodynamic properties of structural units of germanate melts was compiled by according to the results of high-temperature Raman spectroscopy for the correction of physicochemical models. Three mechanisms for the introduction of potassium cations into the germanium-oxygen network are identified along with the effect of composition and temperature on these mechanisms. It is shown that the germanate anomaly maximum shifts with increasing temperature towards low-alkaline compositions due to the appearance of non-bridging oxygen atoms in the system.