Structural, luminescence and judd-ofelt analysis of rare earth doped of magnesium sulfoborate glasses and crystals

Abstract

A series of samples of undoped magnesium sulfoborate glasses and crystals with chemical composition of xMgO+(50‒x) SO3+50B2O3, with 10 ≤ x ≤ 30 mol% were prepared by melt quenching and solid state reaction method respectively. Then a series of glass and crystal samples doped with rare earth (RE = Dy2O3, Eu2O3 and Sm2O3) with the chemical compositions of 10MgO+40SO3+(50‒y) B2O3+yRE, with 0.1≤ y ≤ 1.0 mol% were also prepared by melt quenching and solid state reaction method respectively. The amorphous/crystalline phases of the glass and crystal samples were characterized by X‒Ray diffraction (XRD), while the structural features of the samples were measured using Fourier transform infrared (FTIR), Raman and nuclear magnetic resonance (NMR) spectroscopy. The optical properties of glass and crystal samples were characterized via UV‒Vis‒NIR and luminescence spectroscopy. The amorphous phase of the glass samples was confirmed by the diffused broad XRD pattern, while the crystal samples showed two crystalline phases of H3BO3 and MgSO4(H2O)6. The infrared spectra show the coexistence of BO3, BO4, SO4 2- and S‒O‒B (sulfoborate group) structural units in both glass and crystal samples. The Raman spectra also reveal the coexistence of BO4, SO4 2- and S‒O‒B (sulfoborate group) structural units in both glass and crystal samples. The NMR spectra show the existence BO4 structural units in both glass and crystalline samples. The luminescence spectra of Dy3+ doped glass and doped crystal samples exhibit three emission bands at around 482 nm, 575 nm and 662 nm correspond to the 4F9/2→6H15/2, 4F9/2→ 6H13/2 and 4F9/2→6H11/2 transitions respectively. As for Eu3+ doped glass samples, the emission spectra show peaks at 592 nm, 616 nm, 658 nm and 697 nm correspond to the 5D0→7F1, 5D0→7F2, 5D0→7F3 and 5D0→7F4 transitions respectively, while for crystal samples, the emission spectra show six peaks belongs to Eu2+ and Eu3+ ions. The emission spectra of glass and crystal samples doped with Sm3+ ions show dominant peaks at around 565 nm, 601 nm, 646 nm and 706 nm correspond to the 4G5/2→6H5/2, 4G5/2→6H7/2, 4G5/2→6H9/2 and 4G5/2→6H11/2 transitions respectively. The refractive index and quantum efficiency were calculated for all the studied samples. The higher value of branching ratios from 4F9/2→ 6H13/2 and 4G5/2→6H7/2 transitions showed that Dy3+ and Sm3+ doped magnesium sulfoborate glasses and crystals are good candidates for lasing and lighting device applications.