Crystal chemistry and photoluminescent aspects of down-converted Tb3+ activated SrGdAlO4 nanophosphors for multifunctional applications

Abstract

A series of green radiating terbium (Tb3+) activated SrGdAlO4, i.e., SGAO:xTb3+ (0.01≤ x ​≥ ​0.05) nanocrystalline phosphors has been manufactured with insignificant expenses via a facile and ecological, urea-based solution combustion approach. Crystallographic analysis facilitated by diffraction data and Rietveld refinement revealed pure tetragonal phase with space group 14/mmm (139) for designated nanomaterials. Morphological attributes investigated using scanning and transmission electron micrographs reported weakly agglomerated particles with sizes in the range of 40–60 ​nm. HRTEM micrograph revealed separation between fringes as 0.27 ​nm for miller plane (013), while EDS (energy dispersive X-ray spectrometer) indicated requisite elements of synthesized materials. The lifetime of Tb3+ characterized greenish emission is found in order of 1.39 ​ms. Photoluminescent emission spectra displayed vivid green emission for prepared nanophosphors attributed to 5D4 → 7F5 transition of Tb3+ ions, centered at 549 ​nm. Band-gap studies postulated a wide band-gap value (5.01 ​eV) for optimum SrGd0.97Tb0.03AlO4 nanocrystalline phosphor. Maximum luminescence efficiency was attained at 3 ​mol % doping of Tb3+ ions i.e., for SGAO:0.03 ​Tb3+ nanophosphor with CIE chromaticity coordinates (0.339, 0.579), correlated color temperature (5389 ​K) and color purity (76.4%). The present findings envisaged the utility of designated nanomaterials as promising green emanating specialists for down-conversion white light-emitting diodes.