Optical Absorption of Soda-Lime Industrial Glasses Modified with UV-Absorbing Ions ^†

Due to the concern of the photo-aging effect of ultraviolet (UV) light on biological systems, the investigation of UV-shielding materials has aroused considerable attention in recent years. Although many solutions have already been proposed for the development of UV-shielding devices, most of them involve a polymeric coating or a polymeric matrix. Briefly, current UV-shielding solutions normally suffer from poor UV and thermal stability. Therefore, the development of a transparent inorganic material with high UV protection efficiency and high stability would be of high technological value. In this exploratory study, we investigated the impact of different concentrations of ions (Ce, Zn, and Mn) on the UV absorption and induction of color on an industrial-grade soda-lime glass. For this purpose, commercial soda-lime glass compositions were mixed with at least 0.5%wt and up to 10%wt of CeO₂ or ZnO and with Mn₂O₃ (0.1 up to 1%wt) and melted on a Pt-Rh crucible at 1500 °C for 2 h. The obtained glasses were cut into small plates (5 × 3 × 1 mm) and mirror-polished. All samples were analyzed using UV-Vis spectroscopy and CIELab colorimetry, and all data were analyzed according to the translucency parameter and color change (ΔE). The obtained data indicate that the glasses doped with CeO₂ and ZnO have a better trade-off between UV-shielding and color perceptibility. None of the glasses doped with ZnO presented a perceptible change in color, and only those doped with more than 2.5%wt CeO₂ presented a ΔE above the perceptibility threshold. Additionally, the optical basicity of the soda-lime glass favors the stability of Mn³⁺ and Mn⁴⁺, which is strongly related to the color induction, even for very small concentrations. This preliminary study suggests that it is possible to develop high-quality UV-shielding soda-lime glasses, for 65% of all UV spectra, with imperceptible color changes.