Tunable Cathodoluminescence Properties of Tb3+-Doped La2O3 Nanocrystalline Phosphors

Nanocrystalline Tb 3+ -doped La 2 0 3 phosphors were prepared through a Pechini-type sol-gel process. X-ray diffraction (XRD), field-emission-scanning electron microscopy (FESEM), photoluminescence, cathodoluminescence (CL) spectra, and lifetimes were utilized to characterize the synthesized phosphors. The XRD results revealed that a pure La 2 0 3 phase can be obtained at 700°C. FESEM images indicated that the La 2 O 3 :Tb 3+ phosphors are composed of aggregated spherical particles with sizes ranging from 60 to 100 nm. Under the excitation of UV light and low voltage electron beams (0.5-3 kV), the La 2 O 3 :Tb 3+ phosphors showed the characteristic emissions of Tb 3+ ( 5 D 3,4 - 7 F 6,5,4,3 transitions). The CL colors of La 2 O 3 :Tb 3+ phosphors was tuned from blue to green by changing the doping concentration of Tb 3+ to some extent. The optimum blue CL of La 2 O 3 :Tb 3+ phosphors had better Commission International l'Eclairage (CIE) coordinates and higher emission intensity than those of the commercial product Y 2 SiO 5 :Ce 3+ (blue, product no. 1047, Nichia Kagaku Kogyo Kabushiki, Japan).