Synthesis and Characterization of Monodispersed Rare-earth Ion Doped CeO2 Coated on SiO2 Spheres
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1074-I10-36
Synthesis and Characterization of Monodispersed Rare-earth Ion Doped CeO2 Coated on SiO2 Spheres P. Muralidharan, Seung Hwan Jo, Hyun Wook Lee, and Do Kyung Kim Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong-dong, Yuseong-gu, Daejeon, 305-701, Korea, Republic of ABSTRACT Core–shell microspheres of monodisperse SiO2 coated with rare-earth ion doped CeO2 (Eu3+ Sm3+ and Dy3+) were prepared through a sol-gel method and followed by heat treatment at 800 °C for 4 h. XRD patterns revealed the crystal structures of the doped CeO2 coated on amorphous SiO2 sphere as a shell subsequent to heat treatment at 800 °C. The SEM and TEM images indicated the microstructure of the coating and uniform size distributions of microspheres. Photoluminescence studies showed that the luminescent property had significant influence depending on different dopant ions and the number of layers of shell coated on SiO2 spheres. Keywords: Monodisperse SiO2 spheres; Rare-earth ions; CeO2; Photoluminescence INTRODUCTION Nanostructured functional core-shell composite materials that possess the shape of monodisperse spherical particles can exhibit excellent properties and find applications in the fields of catalysis, separation technology, luminescent devices, bio-labeling and biomaterials engineering [1-7]. Recently, it has been reported that the silica spheres coated with layers of phosphors can form a kind of core-shell structured phosphor material with spherical morphology and the size of the phosphor particles can be controlled by the silica cores [2-4]. The core–shell phosphors have attracted much attention of the researcher because of their different properties from those of single-component materials. CeO2 can be used as a potential photoluminescent host material because of Ce4+ has no 4f electron [8-12]. The rare-earth ion doped CeO2 nanocrystals have been proved to show significant changes in the optical properties, which can find wide applications in various fields. For example, Er doped CeO2 materials have been previously investigated to exhibit excellent upconversion luminescent properties [13]. The spherical phosphors have been possibly prepared by controlling purity of phase, size distribution, surface area and microstructure uniformity of the powder by different wet chemical techniques, such as chemical precipitation, combustion synthesis, hydrothermal, emulsion and sol-gel method [14]. Among the various methods, the sol-gel process has been found to possess low processing temperature, high homogeneity, cost effective and easy synthesis steps to obtained high quality samples. Therefore, this work focus to prepare the rare-earth ion doped (Eu3+, Sm3+, Dy3+) CeO2 nanocrystals and in-situ coating on the surface of silica spheres to form uniform and monodisperse spherical morphological core-shell structure. The samples were
characterized for the structure, morphology, and luminescent properties of the core-shell particles. EXPERIMENT The precursor mater
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