Influence of Modifier Cations on the Spectroscopic Properties of Dy3+ Doped Telluroborate Glasses for White Light Applications

The effect of electronegativity and ion size of the modifier cations have been analyzed through a new series of Dy3+ doped telluroborate glasses prepared by melt quenching technique with the composition of 30TeO2 + 29.5B2O3 + 20MO + 20MF2 + 0.5Dy2O3 (where M = Ba2+, Sr2+, Zn2+, Cd2+ and Pb2+). The various stretching and bending vibrational modes of borate and tellurite network have been identified through FTIR spectral measurements. The conversion of BO3 units into BO4 units increases NBOs in the glass network and the same is confirmed through FTIR spectra. The nephelauxetic ratio (β̅\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \overline{\beta} $$\end{document}) and bonding parameter (δ) value reveals that the Dy–O bond in prepared glasses possesses ionic nature. JO intensity parameters (Ω2, Ω4 and Ω6) of the present glasses follow the trend Ω2 > Ω4 > Ω6 uniformly in all the prepared glasses. Radiative parameters like transition probability (A), stimulated emission cross sectionσpE\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \left({\sigma}_p^E\right) $$\end{document}, branching ratio (βR) values have been predicted from the absorption spectra of Dy3+ ions using JO theory. Among the prepared glasses TBZnD glass posses a better CIE 1931 colour chromaticity coordinates (0.33, 0.39) and CCT value (5019 K). Decay profile of 4F9/2 state of the Dy3+ ion exhibits non-exponential nature due to the interaction between Dy3+-Dy3+ ions. The nature of interaction between Dy3+-Dy3+ ions has been analyzed through Inokuti–Hirayama model and the best fit of S = 6 indicates that the dipole-dipole interaction is responsible for the energy transfer between Dy3+–Dy3+ ions. The glass containing Zn2+ ions posses encouraging results such as higher Y/B intensity ratio, stimulated emission cross section and higher branching ratio (4F9/2 → 6H13/2). Thus the present study identified the Zn2+ ions as a better modifier ion to develop the Dy3+ doped glasses for various photonic applications.