Luminescent properties of YVO4:Eu/SiO2 core–shell composite particles

We report an efficient process for preparing monodisperse SiO2@Y0.95Eu0.05VO4 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@Y0.95Eu0.05VO4 core–shell phosphors. The XRD results demonstrate that the Y0.95Eu0.05VO4 particles crystallization on the surface of SiO2 annealing at 800 °C is perfectly and the crystallinity increases with raising the annealing temperature. The obtained core–shell 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 YVO4:Eu3+ shells on the SiO2 cores could be easily tailored by changing the mass ratio of shell to core (W = [YVO4]/[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.