Upconversion and Downshifting Luminescence from KSrVO4:Er3+ Nanophosphor with Judd-Ofelt Parameters

This study investigates the synthesis and characterization of KSrVO4 phosphors doped with Er3+ ions using combustion synthesis route by using urea as a fuel. X-ray diffraction analysis confirmed the orthorhombic phase and nano-scale crystallite size of around 21 nm, while transmission electron microscopy showed spherical and rod-shaped morphologies. The studies detected upconversion emission spectra at 526, 542 and 643 nm, representing green and red transitions under 980 nm excitation. Downshifting emissions under 350 nm excitation revealed peaks at 492, 544 and 680 nm. The critical quenching concentration was 2.5 mol%, resulting from dipole-quadrupole interactions among dopant ions. The direct and indirect optical band gaps were calculated as 3.61 and 3.41 eV, respectively. The calculated chromaticity coordinates and color correlated temperature values of the phosphor surpassed 5000 K, suggesting its viability for cool LED applications. These findings emphasize KSrVO4:Er3+ as a promising greenish component in white LEDs and a potent upconverting luminescence material for bio-imaging and photovoltaics.