采用溶胶凝胶法制备了核壳结构SiO2@SrAl2Si2O8∶Eu2+粒子. 经1000℃煅烧，在粒径约为350～400nm的单分散SiO2微球表面包覆了一层SrAl2Si2O8∶Eu2+. 分别以X射线粉末衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、光致发光(PL)对合成产物进行了表征. XRD结果表明, SrAl2Si2O8∶Eu2+包覆层为六方相结构; SEM分析表明, 在进行包覆后, 核壳结构SiO2@SrAl2Si2O8∶Eu2+粒子仍然呈良好的单分散状态; TEM分析表明, 核壳结构粒子存在明显的包覆层, 其厚度约为20～30nm; 激发和发射光谱测试表明, Eu2+有效地掺入了SrAl2Si2O8基质中, 并具有良好的发光性能, SiO2@SrAl2Si2O8∶Eu2+的激发光谱峰值在361nm, 发射光谱峰值在441nm, 为Eu2+5d-4f跃迁.
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.
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