Synthesis and Luminescence Properties of Monodisperse Spherical Y₂O₃:Eu³⁺@SiO₂ Particles with Core−shell Structure

Y 2 O 3:Eu 3+ phosphor layers were deposited on monodisperse SiO 2 particles with different sizes (300, 500, 900, and 1200 nm) via a sol−gel process, resulting in the formation of Y 2 O 3:Eu 3+ @SiO 2 core−shell particles. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), time-resolved photoluminescence (PL) spectra, and lifetimes were employed to characterize the Y 2 O 3:Eu 3+ @SiO 2 core−shell samples. The results of XRD indicated that the Y 2 O 3:Eu 3+ layers began to crystallize on the silica surfaces at 600 °C and the crystallinity increased with the elevation of annealing temperature until 900 °C. The obtained core−shell particles have perfect spherical shape with narrow size distribution and non-agglomeration. The thickness of the shells could be easily controlled by changing the number of deposition cycles (60 nm for three deposition cycles). Under the excitation of ultraviolet (250 nm), the Eu 3+ ion mainly shows its characteristic red (611 nm, 5 D 0 − 7 F 2 ) emissions in the core−shell particles from Y 2 O 3:Eu 3+ shells. The emission intensity Eu 3+ can be tuned by the annealing temperature, SiO 2 core size, the number of coating cycles, and polyethylene glycol (PEG) concentration in the precursor solution, respectively.