The Gd2O2SO4 : Yb3+,Er3+ nanoparticles were synthesized by a general and facile hydrothermal synthesis followed bycalcination utilizing commercially available Gd2O3, Yb2O3, Er2O3, HNO3, urea and C12H25SO4Na as the starting materials. Theprecursor and the synthetic products were characterized by a variety of characterization tools. The results reveal that theprecursor is composed of gadolinium hydroxyl, carbonate and sulfate groups and could be converted into pure Gd2O2SO4phase by calcining at 800 oC for 2 hrs in air. The good crystallinity and dispersion of near-spherical Gd2O2SO4 nanoparticleswere obtained with an average diameter of about 50 nm. Under 980 nm infrared light excitation, the Gd2O2SO4 : Yb3+,Er3+nanoparticles present the strongest red emission (664 nm), which corresponds to the 4F9/2 → 4I15/2 transition of Er3+ ions. Moreover, two green emission peaks are located at 546 nm and 526 nm, resulting from the 4S3/2 → 4I15/2 and 2 H11/2 → 4I15/2transitions of Er3+ ions, respectively. When the concentration of Er3+ ions reaches 2%, the Gd2O2SO4 : Yb3+,Er3+ nanoparticlesshows the highest luminescence. The Ln(Iup)-Ln(P) plots confirm that the up-conversion (UC) excitation belongs to two-photon(4F9/2 → 4I15/2 and 4S3/2 → 4I15/2) and three-photon (2H11/2 → 4I15/2) absorption mechanisms.

Keywords: Rare earth oxysulfate, Nanoparticles, Hydrothermal synthesis, Up-conversion luminescence (UCL)