Optical absorption and fluorescent behaviour of titanium ions in silicate glasses

Titanium in normal melting conditions in air atmosphere present as Ti4+ ion in basic silicate glasses exhibited an ultra-violet cut-off in silicate glasses, viz. soda-magnesia-silica, soda-magnesia-lime-silica and soda-lime-silica glasses. This indicates that Ti4+ ion can be a good replacement for Ce4+ ion in producing UV-absorbing silicate glasses for commercial applications. The wavelength maxima at which the infinite absorption takes place in glasses was found to be around 310 mn against Ti-free blank glass in UV-region. The mechanism of electronic transition from O2- ligands to Ti4+ ion was suggested as L --> M charge transfer. The low energy tails of the ultra-violet cut-off were found to obey Urbach's rule in the optical range 360-500 mn. The fluorescence spectra of these glasses were also studied and based on the radiative fluorescent properties it was suggested that the soda-lime-silica glass containing Ti4+ ion with greater emission cross-section would emit a better fluorescence than the corresponding soda-magnesia-lime-silica and soda-magnesia-silica glasses. The shift of emission wavelengths maxima towards longer wavelength in titania introduced silicate glasses was observed on-replacement of MgO by CaO which may be attributed due to an increase in basicity of the glass system.