Luminescent properties of nanoparticles LaSrAl_3O_7:RE~(3+) (RE = Eu, Tb) via the citrate sol-gel method

摘要

Phosphors of nanoparticles LaSrAl_3O_7:RE~(3+) (RE = Eu, Tb) have ben prepared by a sol-gel method. The structure and luminescent properties of LaS-rAl_3O_7:Eu~(3+) and LaSrAl_3O_7:Tb~(3+) phosphors were characterized by X-Ray diffraction (XRD) and atomic force microscopy (AFM), photoluminescence excitation and emission spectra were utilized. From XRD patterns, it is indicated that the phosphor LaSrAl_3O_7 forms without impurity phase at 900 ℃. From AFM images, it is shown that the crystal size of the phosphors are about 60-80 nm. Upon excitation with ultraviolet (UV) irradiation, it is shown that there is a strong emission at around 617 nm corresponding to the forced electric dipole ~5Do-~7F_2 transition of Eu~(3+), and at around 543 nm corresponding to the ~5D_4-~7F_5 transition of Tb~(3+). The dependence of photoluminescence intensity on Eu~(3+) (or Tb~(3+)) concentration and annealing temperature were also studied in detail.