LUMINESCENCE PROPERTIES OF DY³⁺ IONS DOPED IN B<inf>2</inf>O<inf>3</inf>-AL<inf>2</inf>O<inf>3</inf>-CAO-NA<inf>2</inf>O GLASS FOR SOLID STATE LIGHTING APPLICATIONS

Abstract

In this research, the luminescence properties of borate glasses doped with Dy2O3 have been investigated. The glass samples with chemical composition of (40-x)B2O3:20Al2O3:20CaO:20Na2O: xDy2O3 (where x = 0.00, 0.05, 0.10, 0.50, 1.00, and 2.00 mol%) were prepared by the conventional melt quenching technique. The results show that the density and molar volume tend to increase with increasing of Dy2O3 concentration. The excitation spectra are observed seven bands at 325, 351, 364, 387, 425, 452, and 472 nm corresponding to the transitions from the ground state 6H5/2 to excited states 6P3/2,6P7/2, (4I11/2+4P3/2), (4I13/2+4F7/2), 4G11/2,4I15/2, and 4F9/2, respectively. The emission spectra were recorded using 350 nm excitation wavelength. The emission peaks are observed at 482 (4F9/2→6H15/2), 576 (4F9/2→6H13/2), and 664 (4F9/2→6H13/2) nm. The ratio of ED transition to the MD transition is a measure of symmetry orientation of the local environment around the RE ion site which is evaluated for the present work using Yellow/Blue (Y/B) intensity ratio (4F9/2→6H13/2)/ (4F9/2→6H15/2) values. The tunable white light emission at the strongest excitation wavelengths are investigated through CIE 1931 diagram and calculated the correlated colour temperature. The decay curves show the decreasing of lifetimes with addition of Dy2O3 concentration.