Synthesis and Luminescence Properties of Mono-disperse Spherical SiO_2@SrAl_2Si_2O_8∶Eu~(2+) 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 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(361nm).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.