Compositional dependence of Se2− color center formation in silicate glasses

We experimentally verified, within silicate glasses, the formation of Se2− color centers that are responsible for a broad visible emission under optical excitation at UV wavelengths. In addition to Raman spectra, all the spectroscopic analyses on absorption, photoluminescence, and photoluminescence excitation unanimously confirm the formation of Se2− color centers. However, the visible absorption due to Se2− color centers disppeared upon increasing concentration of Na2O, which implies that their formation would depend on the compositions of silicate glasses. The role of Na2O in the formation mechanism in relation to glass structure is then discussed in terms of various analyses on X-ray diffraction patterns, X-ray photoelectron spectroscopy, and Raman spectroscopy.