Impact of MnO on the structural, physicochemical, and dissolution properties of phosphate-based glasses

In this work, manganese was suggested to improve the durability of 50P2O5–33·33K2O–(11·11−x/2) CaO−(5·56−x/2) MgO –xMnO glasses with 0≤x≤ 2 mol%. Indeed, its effect on the glass structure, thermal properties, physicochemical properties, and in particular, dissolution behaviours have been studied. The conventional melt-quenching technique was used to produce glasses at 1000°C and they were characterised by differential thermal analysis, density and molar volume measurements, x-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy. Dissolution behaviours were tracked by measuring weight loss and pH. Molar volume measurements showed that phosphate glasses become more compact by incorporating MnO. Structural characterisation using Raman and infrared spectra proved that the glass network is composed mainly of metaphosphate chains. The dissolution results showed that incorporating manganese was an effective method to change the phosphate glasses’ chemical durability due to their ionic crosslinking between the nonbridging oxygen atoms of the phosphate chains, corresponding to the change in thermal properties (Tg, Tc and Tf).