Color-tunable up-conversion emission of luminescent-plasmonic, core/shell nanomaterials – KY3F10:Yb3+,Tm3+/SiO2-NH2/Au

Abstract

Multifunctional luminescent-plasmonic KY3F10:Yb3+,Tm3+/SiO2-NH2/Au nanomaterials were successfully obtained. The lanthanide-doped fluoride nanoparticles (NPs), synthesized under hydrothermal conditions exhibited bright blue up-conversion luminescence (λex=980nm). Such lanthanide nanocrystals (20–40nm) were coated with amine modified silica shell, forming core/shell nanostructures. Their surface was further uniformly covered with ultra-small gold NPs (4–7nm). The as-prepared luminescent-plasmonic core/shell nanomaterials exhibited tunable up-conversion emission, due to the interactions between plasmonic and luminescent phases. The emission of Tm3+ ion was affected by the surface Au NPs, which exhibited strong plasmonic absorption in the visible range (450–650nm). The increasing amount of the surface Au NPs, led to the significant alterations in a ratio of the Tm3+ emission bands. The NIR band (3H4→3H6) was unchanged, whereas the ratio and relative intensity of the bands in a visible range (1G4→3H6 and 1G4→3F4) was altered. This led to the significant change of the emission spectra shape and influenced color of emission, tuning it from bright blue to blue-violet. The products obtained were characterized by transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), powder X-ray diffraction (XRD), UV–vis absorption spectroscopy and luminescence spectroscopy (excitation/emission spectra and luminescence decay curves).