Physics

A new-fangled series of Dy 3þ ions doped Single and Mixed Alkali Fluoro Tungsten Tellurite Glasses have been prepared by using melt quenching technique and their spectroscopic behaviour was investigated by using XRD, optical absorption, photoluminescence and lifetime measurements. The bonding parameter studies reveal the ionic nature of the DyeO bond in the present glasses. From the absorption spectra, the Judd-Ofelt (J-O) intensity parameters have been determined and in turn used to determine various radiative properties for the different emission transitions from the 4 F 9/2 fluorescent level. The photo-luminescence spectra of all the glasses exhibit two intensified peaks in blue and yellow regions corresponding to the transitions 4 F 9/2 / 6 H 15/2 (483 nm) and 4 F 9/2 / 6 H 13/2 (575 nm) respectively. From the photoluminescence spectra, it is observed that the luminescence intensity is maximum for Dy 3þ ion doped potassium combination of tungsten tellurite glass (TeWK:1Dy). The highest emission cross-section and branching ratio values observed for the 4 F 9/2 / 6 H 15/2 and 4 F 9/2 / 6 H 13/2 transitions suggest the possible laser action in the visible region from these glasses. By correlating the experimental lifetimes (t exp) measured from the decay spectral features with radiative lifetimes (t R), the quantum efficiencies (h) for all the glasses have been evaluated and found to be maximum for potassium combination tungsten tellurite (TeWK:1Dy) glass. The CIE colour chromaticity coordinates (x, y), (u, v), colour correlated temperature (CCT) and Y/B ratio were also estimated from the photoluminescence spectra for different compositions of glasses. The chromaticity colour coordinates evaluated for all the glasses fall within the white light region and white light emission can be tuned by varying the composition of the glass. From all these studies, it was concluded that 1 mol% of Dy 3þ ions doped TeWK glass is more suitable for lasing and white-LED applications.