The ancient glass decoloration technology based on the Fe-Mn redox pairs revived to improve the chemical stability of Fe2O3-containing borosilicate glass for medical application.

MnO has been used for the decoloration of glasses containing iron oxide impurity since ancient times, based on the oxidation-reduction of Fe-Mn redox pairs (Fe2++Mn3+→Fe3++Mn2+). In this work, it was evidenced that a combinative addition of Fe 2 O 3 and MnO into borosilicate glasses for pharmaceutical packaging application induced the above reaction and improved the water resistance of glass. As a comparative study, the structure of glasses with the inclusion of either MnO or Fe 2 O 3 and both of them as well as the valence, coordination of Fe and Mn ions in the glasses were fully investigated by using FTIR, Raman, NMR, EPR, PL and UV–Vis–NIR spectroscopy. It was concluded that the single addition of Fe 2 O 3 or MnO had a similar depolymerization effect on the glass structure, while the co-addition of Fe 2 O 3 and MnO exhibited a synergistic effect, which led to the increase of glass network connectivity due to oxidation-reduction of Fe/Mn redox pairs and consequently the improvement of water resistance of the glasses. [ABSTRACT FROM AUTHOR]