Glycine-assisted hydrothermal synthesis of single-crystalline LaF3:Eu3+ hexagonal nanoplates

In this paper, large-scale LaF3:Eu3+ hexagonal nanoplates with uniform diameter were controllably synthesized by a glycine-assisted hydrothermal method at 150 °C using La(NO3)3, Eu(NO3)3 and NH4F as the reactants. During the synthetic procedure, different amino acids (glycine, lysine and glutamic acid) were first used as the complexing and surface-functionalizing agents for the preparation of rare earth luminescent nanomaterials. Different amino acids molecules have various influence on the formation of the LaF3:Eu3+ nanostructures. X-ray diffraction (XRD) results show that LaF3:Eu3+ are pure hexagonal in structure and no other impurity phase appears. Transmission electron microscope (TEM), field emission scanning electron microscope (FESEM) and selected area electron diffraction (SAED) studies indicate that the single-crystalline LaF3:Eu3+ nanoplates were obtained with in-plane sizes of 90–110 nm and a thickness of 20–25 nm in the presence of glycine, but poly-crystalline and irregular nanoplates were obtained in the presence of lysine and glutamic acids. Photoluminescence (PL) spectra results demonstrate that all the LaF3:Eu3+ nanostructures have two strong 5D0 → 7F1(590 nm) and 5D0 → 7F2(616 nm) transition emission peaks corresponding to orange-red and red color, respectively.