Luminescence and Energy Transfer in Water Soluble CeF_3 and CeF_3:Tb~(3+) Nanoparticles

摘要

CeF_3 and CeF_3:Tb~(3+) water soluble nanoparticles (NPs) were prepared by wet chemistry, and their structure and luminescence properties were studied systematically. The results of XRD indicate that the obtained CeF_3 and CeF_3:Tb~(3+) NPs have a hexagonal structure with the P 6_3/mcm space group. The average size of CeF_3 NPs is about 10 nm, and that of CeF_3:Tb~(3+) NPs is about 5.5 nm as measured from transmission electron microscope (TEM). The aqueous solution sample of CeF_3 NPs has an emission peaking at 325.5 nm, which is from the 5d → 4f transition of Ce~(3+), and CeF_3:Tb~(3+) NPs have a broad emission at 355.5 nm, which is from the 5d → 4f transition of Ce~(3+) (325.5 nm), and several sharp emissions in the visible ranges that are from the ~5D_4 → ~7F_J transition of Tb~(3+). As the concentration of Tb~(3+) increases, the emission intensity of Ce~(3+) decreases gradually, while the emission intensity of Tb~(3+) first increases and then decreases. Our observations indicate that there is an energy transfer from Ce~(3+) to Tb~(3+) in the CeF_3:Tb~(3+) nanoparticles, and the maximal energy transfer rate is estimated to be 93.2% at the Tb~(3+) concentration of 25%.