Red upconverted luminescence in controllable self-assembled RE2O3: Yb3+/Er3+ (RE = Gd, Y) 3D nanoflowers

Abstract

Self-assembled three-dimensional RE2O3: Yb3+/Er3+ (RE = Gd and Y) nanoflowers were synthesized after heating the gadolinium or yttrium carbonate hydrate precursor at high temperature, in which precursors were obtained by a facile co-precipitation process. The precursors and the final products were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectra. The factors those affect the morphology of the final products, including RE-to-urea ratio, pH value of initial solution, reactive temperature and time, were optimized. The formation process of 3D flower-like structure was demonstrated as a time-dependent self-assembly reaction. The up-conversion (UC) spectra of the as-obtained RE2O3: Yb3+/Er3+ (RE = Gd and Y) samples were also discussed as function of morphology, annealing temperature and Yb3+ contents, in which the factors those affect the emitting color or the integrated intensity ratio of red to green were analyzed. High specific surface area and short distance between Yb3+ and Er3+ are conductive to red emission.