Structural, luminescence properties and Judd-Ofelt analysis of rare-earth doped calcium-sulfoborophosphate and barium-sulfoborophosphate glasses

Abstract

Glass samples of undoped calcium-sulfoborophosphate and barium-sulfoborophosphate with chemical composition of xCaSO4-30B2O3-(70-x)P2O5 and xBaSO4- 30B2O3-(70-x) P2O5 with 15 ≤ x ≤ 35 mol% were prepared using melt quenching method. A series of glass samples doped with rare earth (RE = Dy2O3, Sm2O3 and Eu2O3) with the chemical compositions of 25CaSO4-30B2O3-(45-y)P2O5–yRE and 25BaSO4-30B2O3-(45-y)P2O5–yRE with 0.1≤y≤1.0 mol% were also prepared by melt quenching method. The amorphous phase of the glass samples were characterized by X-Ray diffraction (XRD) method, while the structural features of the samples were measured using Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. The optical properties of glass samples were characterized by ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy and luminescence spectroscopy. The amorphous phase of the glass samples was confirmed by the diffuse broad XRD pattern. The infrared spectral measurements revealed the presence of vibrational groups of P-O linkage, BO3, BO4, P-O-P, O-P-O, S-O-B (sulfoborate network) groups and the bending B-O-B units in sulfoborophosphate structural network of glass samples. The Raman spectra also revealed the coexistence of structural units of BO4, SO42-, PO43-, and P-O-P in sulfoborophosphate glass samples. The luminescence spectra of Dy3+ ions doped glass samples exhibit four emission bands at around 482 nm, 572 nm, 662 nm and 685 nm, which correspond to the 4F9/2→6H15/2, 4F9/2→ 6H13/2, 4F9/2→6H11/2 and 4F9/2→6H9/2 transitions, respectively. The emission spectra of glass samples doped with Sm3+ ions show dominant peaks at around 559 nm, 596 nm, 642 nm and 709 nm which correspond to the transitions of 4G5/2→6H5/2, 4G5/2→6H7/2, 4G5/2→6H9/2 and 4G5/2→6H11/2, respectively. Meanwhile, glass samples doped with Eu3+ ions show emission spectra peaks around 589 nm, 611 nm, 651 nm and 701 nm which correspond to the transitions of 5D0→7F1, 5D0→7F2, 5D0→7F3 and 5D0→7F4, respectively. Absorption and emission spectra are used to evaluate the Judd-Ofelt intensity parameters and radiative transition probabilities, branching ratios and stimulated emission cross-sections of the three rare-earth ions (Dy3+, Sm3+, and Eu3+) doped glass system. Based on this study, it can be concluded that the structural network features of calcium sulfoborophosphate and barium sulfoborophosphate glasses are similar, despite of different modifier. The incorporation of sulphate and rare-earth ions into the glass network show enhancement of chemical and physical stability, in addition to improving optical properties performance of the prepared glasses such as having high value of branching ratio, stimulated cross-section, gain bandwidth and optical gain. In view of this, calcium sulfoborophosphate and barium sulfoborophosphate glasses could be suggested as promising luminescent host material for solid-state lighting device application.