Influence of Dy3+ions on the physical, thermal, structural and optical properties of lithium zinc phosphate glasses

Abstract

Lithium zinc phosphate glasses activated with dysprosium ions were prepared by following the melt quenching method. The X-ray diffraction patterns confirmed the non-crystalline structure of the prepared glasses. All the physical parameters are calculated using appropriate formulae. Glass transition (Tg), melting (Tm) and crystallization (Tc) temperature were determined by analyzing the differential thermal curves and these values were used to determine certain thermal parameters. The thermal stability parameter was found to be greater than 100˚C for all the glasses indicating good thermal stability of the glass samples. In order to examine the functional groups and study the structural properties of the prepared glasses, Fourier transform infrared spectrum was recorded for all the glasses. Refractive index is found to be increasing with increase in Dy2O3 concentration. Optical direct and indirect band gaps were determined from Tauc's plots. The emission spectra showed two intense bands at 483 nm (blue) and 574 nm (yellow) along with two feeble bands at 663 nm and 752 nm which are the essential requirements for white LED applications. The maximum luminescence intensity was found in the glass sample with 1mol% Dy2O3. Yellow/Blue intensity ratio, chromaticity coordinates and the correlated color temperature are calculated for all the glass samples. The color coordinates obtained are found to be in the white light region of the CIE 1931 diagram indicating the possibility of using these glasses for white light generation.