Eu3+-ion doped LnF3 NPs: Comparative study of the crystallographic, and photophysical properties

Abstract

The thermal co-precipitation approach was employed for the synthesis of the Eu3+-ion doped YF3, LaF3, and GdF3 nanoparticles (NPs) and compared their photophysical properties. Ammonium fluorite was used as a fluorine source for the synthesis of metal fluorides at lower temperatures. Luminescent lanthanide fluoride (LnF3) NPs were characterized by different techniques containing X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), FT-Raman, UV/Visible absorption spectra, and photoluminescence spectroscopic procedures to investigate the crystal structural, thermal, Raman effect, surface, optical, and luminescent properties. XRD study shows two types of crystal phase orthorhombic in YF3:Eu & GdF3:Eu and hexagonal in LaF3:Eu NPs. TGA, FTIR, and absorption spectra studies show the exterior adsorbed –OH molecules, which assist in the development of colloidal solution in aqueous media. Raman vibrations were strongly affected which were correlated with the XRD reflection planes. In comparative photo-physical properties, the excitation and emission spectra exhibited remarkable intensities of the Eu3+-ion transitions. Similarly, the emission spectra of all three samples exhibited the highest emission efficiency of the magnetically-dipole(5D0→7F2) transition in comparison to the electric-dipole 5D0→7F1 transition, which reflected the transformation of the crystal symmetry. Comparative analysis was presented to investigate the role of the host lattice on crystallinity, thermal stability, and luminescent properties. These findings are highly fruitful in designing photonic-based applications including optical biosensors, fingermark detection, security systems, etc.