Color-tunable luminescence and energy transfer properties of Dy3+/Eu3+ codoped Sr3Sc(PO4)3 eulytite-type orthophosphate phosphors for NUV-LEDs

A series of single-phase and color-tunable Dy3+, Eu3+ singly doped and Dy3+/Eu3+ co-doped Sr3Sc(PO4)3 phosphors have been synthesized via a solid-state reaction method. The crystal structure, phase and constitution of the prepared phosphors were investigated using X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive X-ray (EDX). The excitation and emission spectra, the powder diffuse reflectance spectra (DRS) and fluorescence decays were measured and discussed. The results revealed that Dy3+ can efficiently transfer excitation energy to Eu3+ via its 4f states and therefore sensitized Eu3+ emission under near-ultraviolet (NUV) excitation. Meanwhile, the energy transfer mechanism could be ascribed to be electric dipole-dipole interaction, which can be validated via the linear fitting of the relationship (IS0/IS)∝Cn/3. The Commission Internationale deL'Eclairage (CIE) chromaticity coordinates of the phosphors can be tuned from wathet blue (0.2509, 0.2149) to light orange (0.4022, 0.2924) by adjusting the ratio of Dy3+ and Eu3+. In addition, the CIE coordinate of Sr3Sc0.89(PO4)3:0.07Dy3+, 0.04Eu3+ phosphor was quite close to (0.333, 0.333), which showed that Sr3Sc(PO4)3:Dy3+, Eu3+ phosphors could be used as NUV excitable white light-emitting phosphors.