Sensitized luminescence of water-dispersible CaF2: RE3+ (RE=Eu, Tb, Ce/Tb) nanoparticles through surfactant coating ligands

A facile route has been established for the synthesis of PVP/CaF2: RE3+ and PVP/CaF2: Ce3+ nanoparticles (RE=Eu, Tb, Ce/Tb; PVP=Poly(N-vinyl-2-pyrrolidone)) heated at 70 °C in ethanol at ambient pressure. The as-prepared nanoparticles were shown to be well dispersed in water. The nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The investigation of fluorescence properties showed that there exists energy transfer from the surface coating of PVP to Eu3+ and Tb3+ leading to the sensitized fluorescence emission of Eu3+ and Tb3+. Co-doping the PVP/CaF2: Tb3+ nanoparticles with Ce3+ results in significant increase in the emission intensity of Tb3+ and this has been attributed to the sensitization of Ce3+ and PVP on Tb3+.