Synthesis and Characterization of Single-Crystalline Lanthanum Fluoride with a Ring-Like Nanostructure

摘要

LaF_3 ring-like nanostructures with a diameter of less than 2 __m have been fabricated by a facile, effective, and environmentally friendly molten salt synthesis route in which NaNO_3 and KNO_3 (2:1 molar ratio) act as reaction media and the rare-earth nitrate and NaF as precursor. X-ray diffraction, TEM, HR-TEM, energy dispersive X-ray spectroscopy, and photoluminescence spectroscopy are all used to characterize the as-prepared samples. Experiments peformed with dif_ferent reaction times indicate that a central-etching of the plates from the inner part towards the edge during nanocrystal growth plays a key role in the formation of LaF_3 nanorings since no other templates/surfactants are present in our system. Additionally, the luminescence properties of LaF_3 nano-rings doped with Eu~(3+) cation have been investigated and-compared with those of bulk materials and nanoparticles with a size of approximately 50 nm.