Dy³⁺ doped B<inf>2</inf>O<inf>3</inf> – Li<inf>2</inf>O – CaO – CaF<inf>2</inf> glass for efficient white light emitting sources

Abstract

© 2020 In this present work, Dy3+ doped B2O3 – Li2O – CaO – CaF2 (BLCFDy) glasses with variable concentrations of alkaline and alkaline earth oxide elements are prepared. The X – Ray diffraction technique has been carried out to verify the non crystallinity of BLCFDy glasses. The Fourier Transform Infrared (FT-IR) study reveals that, the structural properties of glasses exhibiting stretching and vibrational groups of various borate groups. The Optical absorption spectroscopy in Ultraviolet – Visible and Near Infrared regions provides glasses have strong absorption in NIR region for excitations 6H15/2 → 6F7/2 (895nm), 6F9/2 (1084nm), 6H9/2 (1267nm) and 6H11/2 (1686nm) states. The Optical band gap measurements prove existence of non-bridging oxygens (NBOs), localization of charges and donor centres in prepared glass samples. Judd–Ofelt hypothesis and intensity parameters (Ω2,Ω4 andΩ6) predicts higher degree of symmetry in covalency and encompassing environment of Dy3+ ions with constituent ligand elements. The radiative properties of glass samples like radiative transition probability (AR), branching ratios both calculated and experimental (βcal & βrad), peak band width (∆λp), stimulated emission cross – section and gain band width (σse x ∆λp) predicts that prepared glasses are good host of lasing materials and optical gain medium. The Photoluminescence emission spectra exhibits two principle strong emissions at 484nm (Blue), 575nm (Yellow) and observable emission at 664nm (Red) owing to de-excitation from 4F9/2 to respective 6H15/2, 6H13/2 and 6H11/2 states. CIE - 1931 chromaticity coordinates (x, y) and CCT values are calculated from photoluminescence emission spectra were found to be within the white light region of the CIE. For the glasses BLCFDy2 and BLCFDy3 colour coordinates (x, y) are (0.34, 0.37), (0.34, 0.38) respectively. The corresponding CCT values are 5223K and 5237K. Thus, BLCFDy2 and BLCFDy3 are the potential candidates for fabrication of white light emitting diodes (W – LEDs) also as laser host materials.