Structural and photophysical measurements of Er3+ doped Gd4Al2O9 nanophosphors for NUV excitable solid-state lighting applications

Green emitting Gd4-xAl2O9:xEr(3+) [x = 1 to 6 mol%] nanophosphors were synthesized via urea assisted solution combustion (SC) synthetic pathway and characterized using X-ray diffraction (XRD), transmission electron mi-croscopy (TEM) observations and spectrofluorophotometric measurements. The structural results obtained by XRD measurements and Rietveld refinement confirm that all prepared nanomaterials are crystallized in monoclinic structure, space group P2(1)/c. The strongest excitation located at similar to 382 nm is strongly matched to the distinct wavelength of commercially accessible NUV excitable LEDs. Under the excitation at 382 nm, all prepared samples exhibit a series of sharp emission bands centred at 411 nm (H-2(9/2) -> I-4(15/2)), 528 nm (H-2(11/2) -> I-4(15/2)), 558 nm (S-4(3/2) -> I-4(15/2)) and 665 nm (F-4(9/2) -> I-4(15/2)), corresponding to transitions of Er3+ ions. The optimum doping concentration of Er3+ ions in the host is determined to be 3 mol%. The photoluminescence lifetime (tau(avg)) determined in Gd3.97Al2O9:0.03Er(3+) phosphor is observed to be around 2.0191 +/- 0.0371 ms. The calculated Commission Internationale de L'Eclairage (CIE) chromaticity coordinates for the optimized phosphor is (x = 0.305, y = 0.592), which is close to the Society of Motion Picture and Television Engineers (SMPTE) (x = 0.310, y = 0.595) coordinates. The study reveals that optimized phosphor could be a potential candidate for near ultraviolet (NUV) excited photonic appliances.