Physical properties and Raman spectroscopy inquiry of copper laden bio-relevant calcium phosphate glasses and the exposed to γ-irradiation

Abstract

Pristine bio-relevant glasses of the P2O5-CaO-Na2O-CuO type where the [CuO]/[Na2O] molar ratios were varied at about 0.1, 0.7 and 1.5 have been scrutinized concerning fundamental physical properties and Raman spectroscopic features. Interpretations were assisted by X-ray photoelectron spectroscopy results regarding the chemical environments of oxygen, phosphorus, and copper. X-ray diffraction measurements performed using Mo-Kα radiation as X-ray source confirmed the amorphous character of the glasses, whereas differential scanning calorimetry showed rising glass transition temperatures with increasing copper content. The densities of the glasses increased linearly with CuO concentration whereas the molar volumes and phosphorus-phosphorus mean distances decreased. Raman results showed variation in the intensities, positions, and widths of main bands with increasing CuO concentration which was attributed to the impact of copper ions with high ionic field strength rather than a depolymerization effect. Finally, the Raman spectroscopy evaluation was extended to γ-irradiated (100 kGy) counterparts for a comparison with the pristine glasses. The γ-irradiated glasses however did not show significant changes in the Raman spectra thus supporting a lack of structural variation after the exposure to the ionizing radiation.