Effects of Gd3+ co-doping on NaYF4:Yb,Er nanoparticles structure

Abstract

NaYF4 doped with Rare Earth elements such as Yb and Er is well known as a compound with the remarkable up-conversion photoluminesce and wide application. In this work, the influence of additional co-doping of NaYF4:Yb,Er with gadolinium (0, 15 and 30 mol%) was explored. The syntheses were performed solvothermally using the mixture of water/ethanol as medium and polyvinylpyrrolidone (PVP) as capping ligand. The obtained powders were subjected to X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy and photoluminesce (PL) analyses. Structural refinement shown that NaYF4:Yb,Er particles generally crystallized in a cubic form (Fm-3m), while the additional presence of Gd3+ in the crystal lattice lead to the pure hexagonal phase crystallization (P63/m). Morphological analyses revealed that all powders are composed from nanodimensional particles with the size in the range of 50-70 nm, while FTIR spectra confirmed the presence of PVP functional groups on the particles surfaces. The strongest effect of Gd3+ doping was notices in the PL spectra, where the up-conversion response increases with the mol% of this dopant.