title: Synthesis, luminescence, and energy-transfer properties of β-Na2Ca4(PO4)2(SiO4):A (A = Eu(2+), Dy(3+), Ce(3+)/Tb(3+)) phosphors.
abstract: A series of β-Na2Ca4(PO4)2(SiO4) (β-NCPS):A (A = Eu(2+), Dy(3+), Ce(3+)/Tb(3+)) phosphors were prepared via a high-temperature solid-state reaction route. The X-ray diffraction, Fourier transform infrared, photoluminescence (PL), cathodoluminescence (CL) properties, fluorescent lifetimes, and absolute quantum yield were exploited to characterize the samples. Under UV radiation, the β-NCPS:Eu(2+) phosphors present bright green emissions, and the β-NCPS:Ce(3+) phosphors show strong blue emissions, which are attributed to their 4f(6)5d(1) → 4f(7) and 5d-4f allowed transitions, respectively. The β-NCPS:Ce(3+), Tb(3+) phosphors display intense tunable color from blue to green and high absolute quantum yields (81% for β-NCPS:0.12Ce(3+) and 83% for β-NCPS:0.12Ce(3+), 0.08Tb(3+)) when excited at 365 nm. Simultaneously, the energy transfer from Ce(3+) to Tb(3+) ions is deduced from the spectral overlap between Ce(3+) emission and Tb(3+) excitation spectra and demonstrated by the change of emission spectra and decay lifetimes. Moreover, the energy-transfer mechanism from Ce(3+) to Tb(3+) ions is confirmed to be exchange interaction according to the discussion of expression from Dexter and Reisfeld. Under a low-voltage electron-beam excitation, the β-NCPS:A (A = Eu(2+), Dy(3+), Ce(3+)/Tb(3+)) phosphors exhibit their characteristic emissions, and the emission profiles of β-NCPS:Ce(3+),Tb(3+) phosphors are obviously different from those of the PL spectra; this difference might be ascribed to their different luminescence mechanisms. These results in PL and CL properties suggest that β-NCPS:A (A = Eu(2+), Dy(3+), Ce(3+)/Tb(3+)) phosphors are potential candidates for solid-state lighting and field-emission displays.
authors.affiliation: State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun, 130022 Jilin P. R. China.
authors.forename: Kai
authors.initials: K
authors.lastname: Li
authors.forename: Mengmeng
authors.initials: M
authors.lastname: Shang
authors.forename: Dongling
authors.initials: D
authors.lastname: Geng
authors.forename: Hongzhou
authors.initials: H
authors.lastname: Lian
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jian
authors.initials: J
authors.lastname: Fan
authors.forename: Jun
authors.initials: J
authors.lastname: Lin