Synthesis and Characterization of Color Tunable Europium(III) and Terbium(III) Co-Doped LaSrAl3O7 Nanocrystalline Phosphors: A Photoluminescent Synergy

Abstract

Color tunable La0.99-xEuxTb0.01SrAl3O7 (x = 0.01-0.07 mol) luminous nanocrystalline materials were synthesized using an affordable, simple, streamlined and self-propagating, urea-assisted solution combustion synthesis route. The X-ray powder diffraction pattern of optimized La0.95Eu0.04Tb0.01SrAl3O7 co-doped phosphor sintered at 900 ºC revealed the formation of single phased phosphor having tetragonal crystalline structure with P421m (113) space group. The field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) micrographs revealed agglomerates featuring spherical-shaped porous nanoparticles with interconnect boundaries and smooth surface. The basic composition was determined via scrutiny of energy dispersive X-ray (EDAX) spectrum. Observations of diffuse reflectance spectroscopy were analyzed to determine the optical band gap values of synthesized Eu3+/Tb3+ co-doped LaSrAl3O7 nanocrystalline luminescent materials. To explore how dopant concentration affected the luminous intensity of phosphors, a thorough examination of the photoluminescence excitation and emission spectra of La0.99-xEuxTb0.01SrAl3O7 (x = 0.01-0.07 mol) was executed. The analysis of luminescence spectra demonstrated that Tb3+ efficiently sensitized the Eu3+ ion. The critical distance (Rc) was calculated to be 5.576 Å and it emerged that non-radiant energy loss occurrence i.e. concentration quenching observed after x = 0.04 mol (Eu3+) doping in La0.99-xEuxTb0.01SrAl3O7 (x = 0.01-0.07 mol) co-doped phosphors was induced by the dipole-quadrupole (d-q) interactions. Moreover, colorimetric attributes including Commission International de I'Eclairage 1931 color coordinates (x, y), color purity and correlated color temperature were obtained by utilization their emission data. The derived nanophosphor materials photometric traits enable new design opportunities for upgraded luminous materials that can be utilized in field emission displays, diverse luminous sources, photonic appliances, phosphor converted light emitting diodes, full-color displays and numerous lighting devices.