Structural and optical studies of rare earth-free bismuth silicate glasses for white light generation

Abstract

We report here rare-earth free bismuth silicate based oxyfluoride glasses (70-x) Bi2O3 30SiO2 xMF (where M = Li, Na & K) with x = 5, 20 & 30 mol% that realizes white light. Bismuth silicate glasses are prepared by melt quenching method and characterized by Raman, Fourier transform infrared (FTIR), UV‐VIS absorption and emission techniques. From the structural analysis, Raman and FTIR, we are able to find presence of BiO6 structural unit in the samples. Optical band gap values of present glass systems that are obtained from absorption spectra vary from 2.91 eV to 3.21 eV. Optical band gap values shows a correlation with theoretically calculated optical basicity values. Urbach energy calculated from absorption spectra gives a measure of disorder of present glass system. Quantitative description of Bi3+ ion interaction with silicate host lattice has been explored through Huang Rhys factor(S). The quality of white light emission is evaluated by CIE color matching function, color purity (CP) and correlated color temperature (CCT).