Concentration and penetration depth dependent tunable emissions from Eu3+ co-doped SrY2O4:Dy3+ nanocrystalline phosphor

A series of Dy3+ ion single-doped and Dy3+/Eu3+ ion co-doped white-light emitting SrY2O4 nanocrystalline phosphors were synthesized by a citrate sol-gel method. After the samples were annealed at 1300 degrees C, the X-ray diffraction patterns confirmed their orthorhombic structure. The particles were closely-packed and their optical properties were monitored by photoluminescence spectroscopy. The Dy3+ ions acted as luminescent centers and substituted Y3+ ions in the SrY2O4 host lattice, where they are located in C-s sites, and the characteristic emission of Dy3+ ions (F-4(9/2) -> H-6(15/2) and F-4(9/2) -> H-6(13/2) transitions) with intense yellow emission band at 578 nm occurred. When the Eu3+ ions were co-doped into the SrY2O4:Dy3+ (1 mol%) nanocrystalline phosphor, white-light emission was observed under excitation at 381 nm. The energy transfer between Eu3+ and Dy3+ ions was calculated and the chromaticity coordinates were also presented. The cathodoluminescence (CL) spectra confirmed that the penetration depth is inversely proportional to the total atomic weight and atomic number of the compound. From CL analysis, the emission intensities of Dy3+ ion single-doped and Dy3+/Eu3+ co-doped SrY2O4 nanocrystalline phosphors increased continuously upon increasing both the accelerating voltage from 1 to 5 kV and the filament current from 30 to 47 mu A.