Self-assembly NaGdF₄nanoparticles: phase controlled synthesis, morphology evolution, and upconversion luminescence properties

Cubic NaGdF4:Yb0.2Er0.02 (α-NaGdF4), self-assembly cubic NaGdF4:Yb0.2Er0.02, and high-resolution structure of hexagonal NaGdF4:Yb0.2Er0.02 (β-NaGdF4) nanoparticles are prepared via the co-thermolysis of Gd(CF3COO)3 and CF3COONa in the presence of 1-octadecene as stabilizer and oleic acid as ligand. Transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), x-ray power diffraction (XRD), and Hitachi F-4600 fluorescence spectrophotometer are used for the characterization of the samples. The results show that by tuning the ratio of CF3COONa/Gd(CF3COO)3 and the reaction temperature, we can control the crystal phase, the relative intensity of upconversion luminescence of nanoparticles, and the morphology evolution of self-assembled α-NaGdF4 nanoparticles.