![]() The cores are black spheres with an average size of 300 nm, and the shells have gray color with an average thickness of 20 nm. The PL intensity of Eu 3+ increases with increasing the annealing temperature and the values of W. 5, the coreshell structure for the SiO 2 YVO 4 :Dy 3+ particles can be seen clearly due to the different electron penetrability for the cores and shells. The Eu 3+ shows a strong PL luminescence (dominated by 5D 0 - 7F 2 red emission at 618 nm) under the excitation of 320 nm UV light. The thickness of the YVO 4:Eu 3+ shells on the SiO 2 cores could be easily tailored by changing the mass ratio of shell to core ( W = /) ( 50 nm for W = 30%). 500 nm and an average thickness of 50 nm), are not agglomerated, and have a smooth surface. of YVO4:Eu3+ Nanoparticles via a Novel Core-Shell and Hybridization Approach. The obtained core-shell phosphors have a near perfect spherical shape with narrow size distribution (average size ca. Photoluminescence Spectroscopy of YVO4:Eu3+ Nanoparticles With Aromatic. Layers via Sol-Gel Process: A Simple Method To Obtain Spherical Core-Shell Phosphors. This is mainly because the SiO 2 on the surface of the NCs forms a protecting layer, which would effectively isolate the Eu 3+ ions from water and thus reducing the deleterious effects of water on the luminescence yield. The XRD results demonstrate that the Y 0.95Eu 0.05VO 4 particles crystallization on the surface of SiO 2 annealing at 800 ☌ is perfectly and the crystallinity increases with raising the annealing temperature. After the YVO 4 :Eu cores were coated by a shell of SiO 2, the emission intensity increased substantially. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectra were used to characterize the resulting SiO 0.95Eu 0.05VO 4 core-shell phosphors. We report an efficient process for preparing monodisperse SiO 0.95Eu 0.05VO 4 core-shell phosphors using a simple citrate sol-gel method and without the use of surface-coupling silane agents or large stabilizers.
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