White light emission from Dy 3+ doped LiCl-CaO-Bi 2 O 3 -B 2 O 3 glasses

Abstract

LiCl-CaO-Bi 2 O 3 -B 2 O 3 glasses with different amount of Dy 3+ were prepared through conventional melt quench route. Various techniques viz. X-ray diffraction, UV-Vis-NIR spectroscopy and photoluminescence has been carried out to study structural, optical and luminescence behavior of prepared glasses. Six absorption peaks were identified in the optical absorption spectra which corresponds to the transition of Dy 3+ ion from 6 H 15/2 ground state to 4 I 15/2 , 6 F 5/2 , 6 F 7/2 , 6 F 9/2 , 6 H 9/2 and 6 H 11/2 excited states. The indirect allowed as well as forbidden optical band gap using Tauc's plot has also been calculated and reported in the present study. The emission spectra of prepared glasses were recorded at ambient temperature with fixed excitation wavelength of 451 nm and corresponding to this, three different peaks at ∼ 484nm, ∼ 575 nm and ∼663 nm were observed. Various emission parameters like (x,y) color coordinates, yellow to blue (Y/B) intensity ratio and correlated color temperature (CCT) has been determined using emission spectra. The (x,y) color coordinates of all the glassy samples were found to lie very close to that of pure white light (0.33,0.33). The CCT of all prepared samples was observed to lie in the cool white region (6500-8725 K) and hence these materials can be used as promising alternative material for outdoor luminescence applications.