Size controllable synthesis and multicolor fluorescence of SiO2:Ln3+(Ln=Eu, Tb) spherical nanoparticles

A series of size controllable Tb3+ and/or Eu3+ activated nano-sized silica phosphors have been successfully synthesized through a facile sol-gel method. The structure, morphology, compositions, and luminescence properties of as-prepared samples were well investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) and photoluminescence spectroscopy (PL). The results showed that all as-prepared samples were spherical nanoparticles but the sizes reduced gradually with the temperature increased from 25 °C to 65 °C, which was contrary to the BET surfaces as well as the luminescence intensity. Under ultraviolet excitation, the SiO2:Ln3+(Ln=Eu, Tb) spherical nanoparticles showed characteristic red and green emissions corresponding to f-f transition of Eu3+ and Tb3+, respectively. Moreover, the luminescence emissions of samples can be tuned from green to yellow, orange and red by co-doping the Tb3+ and Eu3+ ions in different concentration ratio into the SiO2 host due to the efficient dipole-dipole energy transfer mechanism from Tb3+ to Eu3+ under 377 nm excitation. These results show that as-prepared phosphors may find potential applications in color display fields.