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

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 ([Formula: see text]) 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 section[Formula: see text], branching ratio (β_R) 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 ⁴F_9/2 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 (⁴F_9/2 → ⁶H_13/2). Thus the present study identified the Zn²⁺ ions as a better modifier ion to develop the Dy³⁺ doped glasses for various photonic applications.