Luminescence properties and energy transfer behavior of single-component NaY(WO4)2:Tm3+/Dy3+/Eu3+ phosphors for ultraviolet-excited white light-emitting diodes

The single-component NaY(WO4)(2):Tm3+/Dy3+/Eu3+ color-controllable phosphors were synthesized by a facile high-temperature solid-state reaction technique. The X-ray diffraction patterns, field-emission electron scanning microscope images and photoluminescence (PL) spectra were measured to characterize the prepared phosphors. All the samples possessed pure tetragonal phase and consisted of micro-sized particles. Under ultraviolet light excitation, the characteristic emissions of Tm3+, Dy3+ and Eu3+ ions were observed. Moreover, the emission color of the NaY(WO4)(2):Tm3+/Dy3+/Eu3+ phosphors was tuned from blue to white by adjusting the Dy3+ ion concentration. The PL spectra revealed that there existed an efficient energy transfer (ET) from Tm3+ to Dy3+ ions and the ET mechanism was determined to be a resonant type via dipole-dipole interaction. Through theoretical calculation, the ET efficiency was found to be as high as 46.1% when x = 0.05 and the critical distance was 6.54 angstrom. With the introduction of Eu3+ ions, the corrected color temperature of the products was modified and the emission color was also changed from pure white to reddish white. These obtained single-component white light-emitting NaY(WO4)(2):Tm3+/Dy3+/Eu3+ phosphors were expected to be a potential candidate for phosphor-converted white light-emitting diode applications. (C) 2016 Elsevier B.V. All rights reserved.