Dy3+-doped P2O5-Al2O3-K2O-CaF2-LiF glasses: thermal, spectroluminescence and photometric properties

Fluorophosphate (PAKCLf: P2O5-Al2O3-K2O-CaF2-LiF) glasses with Dy3+ concentration of 0.01, 0.05, 0.1, 0.5, 1.0, 2.0 and 3.0 mol% were fabricated by pouring the melt and sudden quenching process. The glass stability factor of 106 degrees C was calculated by glass transition (563 degrees C) and crystallite (669 degrees C) temperatures. The energy bandgap (E-g) of Dy3+:PAKCLf glasses is calculated for (alpha h nu)(2) (direct) and (alpha h nu)(1/2) (indirect) allowed transitions. From optical absorption, the oscillator strength and spectroscopic intensity (ohm(2,4,6)) parameters by performing Judd-Ofelt calculations were estimated to evaluate the radiative transition properties of F-4(9/2) level in Dy3+ ions. The emission spectra consist of two intense bands in blue (485 nm: F-4(9/2)-> H-6(15/2)) and yellow (576 nm: F-4(9/2)-> H-6(13/2)) regions by stimulating at 349 nm. The decay curves demonstrate the non-exponential nature from 0.5 to 3.0 mol% of Dy3+ and fitted well to the Inokuti-Hirayama model. The findings of stimulated emission cross-section (5.20 x 10(-21) cm(2)), optical gain (29.59 x 10(-25) cm(2)s), and quantum efficiency (97%) for Dy3+:PAKCLf glasses could be potentially utilized as optical devices. The photometric parameters like CIE colour coordinates and correlated colour temperatures (CCT:6300-6900 K) of Dy3+:PAKCLf glasses reveal the application of white light-emitting diodes.