Nanocrystalline CaYAlO4:Tb3+/Eu3+ as promising phosphors for full-color field emission displays

Eu3+ and/or Tb3+-doped CaYAlO4 phosphor samples were synthesized by Pechini-type sol-gel method. X-Ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), photoluminescence (PL) and cathodoluminescence (CL) spectra were used to characterize the samples. For CaYAlO4:Tb3+, it is shown that the Tb3+-doping concentration has a significant effect on the D-5(3)/D-5(4) emission intensity of Tb3+, which is attributed to the cross relaxation from D-5(3) to D-5(4). Under the 4f(8) -> 4f(7)5d excitation of Tb3+ or low-voltage electron beams excitation, the CaYAlO4:Tb3+ phosphors show tunable luminescence from blue to cyan, and then to green with the change of Tb3+-doping concentration. The CaYAlO4:Eu3+ samples exhibit a reddish-orange emission of Eu3+ corresponding to D-5(0,1) -> F-7(0,1,2,3) transitions. Furthermore, a white emission can be realized in the single phase CaYAlO4 host by reasonably adjusting the doping concentrations of Tb3+ and Eu3+ under low-voltage electron beams excitation. Compared with the commercial blue (Y2SiO5:Ce3+) and green (ZnO:Zn) phosphors, CaYAlO4:0.1%Tb3+ and CaYAlO4:5%Tb3+ phosphors have higher CL intensity and stability under continuous electron bombardment. Due to the excellent CL properties and good CIE chromaticity coordinates, the as-prepared Tb3+/Eu3+-doped CaYAlO4 nanocrystalline phosphors have potential application in FEDs devices.