Abstract: In order to develop novel single phase phosphors for warm white LEDs with superior stability, easy synthesis, strong absorption in near ultraviolet matching blue chip and high luminescence efficiency, novel single phase Sr₂V₂O₇(SVO):Ln(Ln=Eu³⁺, Dy³⁺, Sm³⁺, Tb³⁺) phosphors for white LEDs were prepared by the high-temperature solid-state reaction method under air atmosphere. The crystal structures,photoluminescence (PL) properties and energy transfer between the host and rare earth ions were investigated by X-ray diffraction (XRD) patterns and luminescence spectra. SVO phosphor is a novel phosphor for near ultraviolet white LEDs, emitting intense and broad yellow-greenish light upon the 350 nm excitation. It is concluded from the photoluminescence spectra that all samples doped with rare earth ion exhibited a broad near ultraviolet band due to charge transfer transition of the SVO host, indicating that there were energy transfers from the host SVO to Eu³⁺, Dy³⁺, Sm³⁺, Tb³⁺ ions, respectively. Furthermore, the energy transfers from VO₄^3- to rare earth ions occurred mainly via dipole-dipole interactions according to Dexter's theory. The results shows that through doping rare-earth ions into SVO host,the luminescent intensity was enhanced, the CIE coordinates were adjusted and the correlated color temperature were reduced, demonstrating that phosphors SVO:Ln (Ln=Eu³⁺, Dy³⁺, Sm³⁺, Tb³⁺) phosphors are promising single phase converting phosphors for white LEDs with near UV chips.

Key words: Sr₂V₂O₇, white LEDs, near ultraviolet, energy transfer