Host-sensitized luminescence of Dy3+, Pr3+, Tb3+ in polycrystalline CaIn2O4 for field emission displays

CaIn2O4:Dy3+/Pr3+/Tb3+ blue–white/green/green phosphors were prepared by the Pechini sol–gel process. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), diffuse reflectance, photoluminescence (PL) and cathodoluminescence (CL) spectra as well as lifetimes were utilized to characterize the samples. The XRD results reveal that the samples begin to crystallize at 800 °C and pure CaIn2O4 phase can be obtained after annealing at 900 °C. The FE-SEM images indicate that the CaIn2O4:Dy3+, CaIn2O4:Pr3+ and CaIn2O4:Tb3+ samples consist of spherical grains with size around 200–400 nm. Under the excitation of ultraviolet light and low-voltage electron beams (1–5 kV), the CaIn2O4:Dy3+, CaIn2O4:Pr3+ and CaIn2O4:Tb3+ phosphors show the characteristic emissions of Dy3+ (4F9/2–6H15/2 and 4F9/2–6H13/2 transitions, blue–white), Pr3+ (3P0–3H4, 1D2–3H4 and 3P1–3H5 transitions, green) and Tb3+ (5D4–7F6,5,4,3 transitions, green), respectively. All the luminescence is resulted from an efficient energy transfer from the CaIn2O4 host lattice to the doped Dy3+, Pr3+ and Tb3+ ions, and the corresponding luminescence mechanisms have been proposed.