Optical and X-ray induced luminescence of Sm3+ -doped borotellurite and fluoroborotellurite glasses: A comparative study

Abstract

Borotellurite and fluoroborotellurite glasses doped with Sm3+ ions were synthesized and studied their physical, photoluminescence, x-ray induced luminescence, and fluorescence decays. The glasses that were prepared by melt quenching technique were labelled by BTZOS for 30B2O3 ​+ ​29TeO2 ​+ ​30BaO ​+ ​10ZnO ​+ ​1Sm2O3 and BTZFS for 30B2O3 ​+ ​29TeO2 ​+ ​30BaO ​+ ​10ZnF2 ​+ ​1Sm2O3. The glass becomes more transparent when ZnO was replaced by ZnF2. It was found that the replacement of ZnO by ZnF2 increases absorbance and luminescence of Sm3+ ions. The Judd - Ofelt intensity parameters were evaluated from measured absorption spectra for BTZOS and BTZFS glasses and their trend is found to be Ω2 > Ω4 > Ω6. The sharp and intense emission peak was originated from 4G5/2 → 6H7/2 transition centred at 600 nm under 403 nm excitation. The colour coordinates of BTZOS and BTZFS glasses are found to fall in the orange region with CCT <4000 K, suitable for solid-state lighting. BTZFS glass exhibits better radiative properties such as long lifetime, higher quantum efficiency (η), radiative transition probability (AR), stimulated emission cross-sections (σe), branching ratios (β), gain bandwidth and figure of merit, lower non-radiative decay rate (WCR) and saturation intensity (Is) than BTZOS glass. From the analysis of the results, it is concluded that BTZFS glass could be more suitable for a gain medium for lasers in the visible region.