Physical, thermal, structural and optical properties of Dy3+ doped lithium alumino-borate glasses for bright W-LED

Abstract

Rare earth (RE) doped glasses have potential applications due to their emission efficiencies of 4f–4f and 4f–5d electronic transitions. Among all the rare earths, Dy3+ doped glasses have drawn much interest among the researchers for their intense emission in the visible region from 470 to 500nm and around 570 to 600nm. The physical, thermal, structural and optical properties of Dy3+ doped lithium alumino-borate glasses (LABD glasses) have been studied for white LED (W-LED) application. The glasses were synthesized by conventional melt quench technique. X-ray diffraction spectra revealed the amorphous nature of the glass sample. An FTIR spectrum was carried out to study the glass structure and various functional groups present in the LABD glasses. Optical absorption spectra were recorded by UV–vis-NIR spectrometer. Allowed direct and indirect band gaps were obtained by Tauc's plot. Thermal parameters like glass thermal stability (∆T), Hruby's parameter (Kgl), etc. were calculated by DTA graph. Photoluminescence excitation and emission spectra's were measured at room temperature. The emission spectra shows two intense emission bands at around 482nm (blue) and 574nm (yellow) corresponds to the 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions respectively along with one feeble band at 662nm (red) corresponds to 4F9/2→6H11/2 transition. The CIE chromaticity co-ordinates were calculated for all glass samples. CIE chromaticity diagram shows glass LABD-4 containing 0.5mol% Dy2O3 with colour co-ordinates X = 0.34 and Y = 0.38 have highest emission intensity. These glasses having emission in the white region and thus can be used for bright white LED.