Tunable green to red emission via Tb sensitized energy transfer in Tb/Eu co-doped alkali fluoroborate glass

A new series of emission-tunable alkali fluoroborate glasses with molar composition (70-x-y)B₂O₃ + 10BaO + 10K₂O + 10ZnF₂ + xEu₂O₃ + yTb₄O₇ (y = 0.0, 1.0 mol% and x as 0.0, 0.1, 0.2, 0.5 and 1.0 mol%) were prepared using the conventional melt quenching technique. The photoluminescence characteristics of the prepared glasses were explored and the efficient energy transfer between Tb³⁺ ions and Eu³⁺ ions under 484 nm excitation was confirmed using excitation and emission spectra. The photoluminescence and lifetime measurements reveal the efficient energy transfer from Tb³⁺ to Eu³⁺ through quadrupole–quadrupole interaction between the rare earth ions. The important energy transfer parameters such as energy transfer probability and transfer efficiency were computed. The energy transfer efficiency was considerably increased with an increase in the concentration of Eu³⁺ ions. The CIE chromaticity analysis revealed that the as obtained glassy system exhibits a greenish-orange emission with a low concentration of Eu³⁺ ions and can be tuned to orange-red emission by increasing the concentration of Eu³⁺ ions. The obtained results suggest that the prepared glassy system has potential applications in various optoelectronic devices.