Photoluminescence characteristics of the single-host white-light-emitting Sr3−3x/2(VO4)2:xEu (0≤x≤0.3) phosphors for LEDs

In this article, the single-host white-light-emitting Sr3−3x/2(VO4)2:xEu (0≤x≤0.3) phosphors were synthesized by solution combustion method using citric acid as a fuel. The synthesized phosphors were annealed at 850–1150 °C for 10 h. At first, the photoluminescence (PL) characteristics of the prepared Sr3−3x/2(VO4)2:xEu (0≤x≤0.3) phosphors emit bluish-green light with the maximum wavelength at 510 nm and sharp red emission at 611 nm under 360 nm excitation, due to the charge transfer transitions of image and f–f transitions of Eu3+ ions, respectively. The XRD results show that as the europium concentration is increased, an additional EuVO4 secondary phase is formed, which is efficient red-emitting phosphor. On the other half, the luminescence intensity of imagedecreases when the annealing temperature increases with emerging of the 5D0–7FJ (J=1, 2) transitions of Eu3+ due to efficient energy transfer from vanadate group to Eu3+. Thus, the Sr3−3x/2(VO4)2:xEu (0≤x≤0.3) phosphors were affected by the Eu3+ contents and annealing temperature. In addition, the optimal composition is found to be Sr2.85Eu0.1(VO4)2 at 1150 °C. Our results suggest that the Sr3−3x/2(VO4)2:xEu (0≤x≤0.3) phosphors may be good candidate for a new phosphor to convert the near-UV(ultraviolet) into visible wavelength bands.