Luminescent properties of YVO₄:EU/SiO₂ core-shell composite particles

We report an efficient process for preparing monodisperse SiO ₂@Y_0.95Eu_0.05VO₄ core-shell phosphors using a simple citrate sol-gel method and without the use of surface-coupling silane agents or large stabilizers. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectra were used to characterize the resulting SiO₂ @Y_0.95Eu_0.05VO₄ core-shell phosphors. The XRD results demonstrate that the Y _0.95Eu_0.05VO₄ particles crystallization on the surface of SiO₂ annealing at 800 °C is perfectly and the crystallinity increases with raising the annealing temperature. The obtained coreshell phosphors have a near perfect spherical shape with narrow size distribution (average size ca. 500 nm and an average thickness of ∼ 50 nm), are not agglomerated, and have a smooth surface. The thickness of the YVO ₄:Eu³⁺ shells on the SiO₂ cores could be easily tailored by changing the mass ratio of shell to core (W-[YVO ₄]/[SiO₂]) (∼50 nm for W-30%). The Eu³⁺ shows a strong PL luminescence (dominated by ⁵D₀- ⁷F₂ red emission at 618 nm) under the excitation of 320 nm UV light. The PL intensity of Eu³⁺ increases with increasing the annealing temperature and the values of W.