Concentration Effect of Glass Former on the Lumenescene Properties of Tb³⁺-Ions Doped Na₂O–CaO–B₂O₃–TeO₂ Glasses for Laser Applications

In this work we prepared boro-telluride glass samples while varying the concentration of TeO₂ (0.00, 10.00, 20.00 mol %) by melt quenching technique and study their physical, optical and luminescence properties by various characterization methods. We found that band gap lies in the 2.88–2.18 eV range, showing decreasing trend with increasing concentration of TeO₂. The emission spectra shows four emission peaks under 378 nm excitation centered at 486, 545, 590 and 620 nm because of the transition from ⁵D₄ state to ⁷F_J (where, J = 6, 5, 4, 3) lower levels. Whereas the intensity decreases with increasing concentration of TeO₂, indicating that the non-radiative energy transfer through cross relaxation (CR) increases with increasing concentration of TeO₂. The color coordinates for all studied glasses fall in green region and were (x = 0.304, y = 0.605). The CCT obtained value for all prepared glasses is 6000 K. Above study suggests that these glasses can be potentially used in green light LEDs and in other solid state lighting applications.