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°C was calculated by glass transition (563°C) and crystallite (669°C) temperatures. The energy bandgap (Eg) of Dy3+:PAKCLf glasses is calculated for (αhν)2 (direct) and (αhν)1/2 (indirect) allowed transitions. From optical absorption, the oscillator strength and spectroscopic intensity (Ω2,4,6) parameters by performing Judd–Ofelt calculations were estimated to evaluate the radiative transition properties of 4F9/2 level in Dy3+ ions. The emission spectra consist of two intense bands in blue (485 nm: 4F9/2→6H15/2) and yellow (576 nm: 4F9/2→6H13/2) 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 × 10–21 cm2), optical gain (29.59 × 10–25 cm2s), 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.