Synthesis and Luminescence Properties of Mono-disperse Spherical SiO2@SrAl2Si2O8:Eu2+ Particles with Core-shell Structure

Nanocrystalline SrAl2Si2O8 : Eu2+ phosphor layers were coated on non-aggregated, mono-dispersed, and spherical SiO2 particles by sol-gel process at relatively low temperature, resulting in the formation of core-shell SiO2 @ SrAl2Si2O8 : Eu2+ particles. X-ray diffraction, scanning electron microscope (SEM), transmission electron microscope (TEM), as well as photoluminescence were utilized to characterize the core-shell structured SiO2 @ SrAl2Si2O8 : Eu2+ particles. XRD analysis confirms the formation of SiO2@SrAl2Si2O8 : Eu2+ particles, it indicates that the SiO2 @ SrAl2Si2O8 : Eu2+ phosphor layers coated on SiO2 particles are hexagonal crystal phase. SEM and TEM indicate that the roughness of the SiO2 particles' surface obviously increases. The obtained core-shell phosphors consist of well dispersed submicron spherical particles with a narrow size distribution, and the thickness of coated layers is about 20 - 30nm. The core-shell particles show strong blue emission, which is ascribed to transition from 5d to 4f (around 440nm) of Eu2+ under the excitation of ultraviolet light (361 nm) The excitation and emission spectra show that Eu2+ can be incorporated into SrAl2Si2O8 effectively. The study of optical properties suggest that these particles may be used in plasma display panel (PDP) device and other luminescent apparatus.