Enhanced UV transparency in phosphate glasses: Via multi-wall carbon nanotubes
Multi-wall carbon nanotubes are systematically explored for the first time as a means to obtain an enhanced ultraviolet (UV) transparency in melt-quenched phosphate glasses. An optical characterization is carried out by UV/Vis transmission and photoluminescence spectroscopy including time-resolved measurements. 31P nuclear magnetic resonance, Raman microspectroscopy, differential scanning calorimetry and X-ray photoelectron spectroscopy are employed to further investigate the source of the improved UV light transmission. The data suggest that the formation of P-O-C bonds is connected to the enhanced UV transparency. A model is presented accounting for the incorporation of carbon into the phosphate network facilitated by the creation of intermediate reactive oxygen species.