Green emitting SrAl2O4:Tb3+ nano-powders for forensic, anti-counterfeiting and optoelectronic devices

Tb3+ ions incorporated strontium aluminate nanopowders were prepared via eco-friendly green ultrasonication followed by combustion method by using Carica papaya milk extract as a fuel/surfactant. The prepared powders were characterized by advanced characterization techniques. X-ray diffraction profiles of the prepared samples confirmed the monoclinic phase of SrAl2O4:Tb3+ (1–11 mol%) and well consistent with PDF number of 74-0794. Rod, mesh and spikes like morphology were confirmed through SEM images. TEM images showed the irregular extended particles with smooth surface and confirm the polycrystalline nature of prepared nanopowders. Upon excitation at 374 nm the photoluminescence emission spectra show intense peaks in the range at 480–620 nm due to the transitions 5D4 → 7FJ (J = 6, 5, 4 and 3) of Tb3+ ions. CIE, CCT and CP results observed were corresponding to intense green colour with (0.21, 0.71), 4621 K and 90% respectively. 7 mol % of Tb3+ doped strontium aluminate was found more suitable for the production of green light component of WLED and for display applications. These compounds were also showed better visualization capabilities to view the LFPs on different porous and nonporous surfaces. Nanopowders were strongly adsorbed by the surfaces which help to visualize the various ridge features including sweat-pores without any background hindrance. UV light of 254 nm wavelength exhibited the clearly visualized symbols with intense green light used for anti-counterfeiting.