Comparative study of synthesis and characterization of monodispersed SiO2 @ Y2O3:Eu3+ and SiO2 @ Y2O3:Eu3+ @ SiO2 core-shell structure phosphor particles

Monodispersed SiO2 @ Y2O3:Eu3+ and SiO2 @ Y2O3:Eu3+ @ SiO2 nanospheres contain SiO2 as core and Y2O3:Eu3+ as shell or another SiO2 shell coated on the surface of SiO2 @ Y2O3:Eu3+ particles were synthesized, respectively. The synthesis of core-shell particles SiO2 @ Y2O3:Eu3+ involved the SiO2 core ultrasonically dispersed into a certain amount of polyethylene glycol solution, and the deposition of Y2O3:Eu3+ on the surface of SiO2 core through homogeneous precipitation of Y3+ and Eu3+ using urea as precipitator. More over, the particles SiO2 @ Y2O3:Eu3+ as core was ultrasonically dispersed into a certain amount of ethanol and followed by sol-gel processing of tetraethoxysilane to form another silica shell. The morphology structures and sizes of the resulting particles were analyzed by SEM and TEM, which indicated that the resulting particles dispersed regularly and the microstructures of the particles are clearly core-shell or core-shell-shell structures. XRD patterns characterized the crystal structures of deposited Y2O3:Eu3+ shell or SiO2 shell after heat treatment at 900 °C. Photoluminescence determination showed that both the phosphors can be excited by ultra violet at 254 nm which showed red-shift. Under the excitation at 254 nm, the Eu3+ ion mainly shows its characteristic red (612 nm, 5D0-7F2) emission in the particles from Y2O3:Eu3+ shell. The emission intensity of Eu3+ was affected by the SiO2 core or shell in some extent.