Bright red frequency upconversion and blue frequency downconversion in asparagine-chelated Nd3+/Tb3+ co-doped tetragonal orthovanadate nanoparticles

Abstract

A series of tetragonal LaVO4 nanoparticles (NPs) with varying concentrations of co-dopants (Nd3+/Tb3+) is synthesized using the bottom-up assembly method. Lattice dynamics and the connection between vanadium-oxygen bond distance (R) and vanadium-oxygen Raman stretching frequency (ʋ) are evidently proven using Raman analysis at 532 & 638 nm excitations. Stoke's and Anti-Stoke's emission of the developed nanophosphors are studied under 261 & 808 nm excitations respectively, and the plausible mechanism is depicted as an energy level diagram. Exchange interaction (θ ≃ 3) is obviously responsible for the cross-relaxation-induced quenching of Nd3+/Tb3+ ions. CIE coordinates of co-doped LaVO4 NPs show up in bluish and orange-red colors, extending its multi-color labeling applications.