Effect of copper addition on glass transition of silicate–phosphate glasses

Glass transformation effect of mixed SiO2–P2O5–K2O–MgO–CaO–CuO glasses was studied by DSC, XRD, SEM, and Raman spectroscopy methods. The relationship between the parameters characterizing glass transformation effect and an amount of phosphorous and copper forming the glassy structure was discussed. It was shown that an increasing content of phosphorous increased solubility of copper in the structure of the studied glasses which was the result of P–O–Cu bonds formation. Degree of changes of Tg, ∆cp, and time of relaxation values were higher in glasses with higher content of P2O5 and CuO. The observed relations were explained on the basis of the local atomic interactions in the structure of glass.