; Zhang, Jing
; Chen, Xing
; Chen, Zhongjun
; Sun, Minhua
; Wu, Ziyu] Chinese Acad Sci, Inst High Energy Phys, Beijing Synchrotron Radiat Lab, Beijing 100039, Peoples R China
; [Guo, Lin] Beijing Univ Aeronaut & Astronaut, Sch Mat Sci & Engn, Beijing 100083, Peoples R China
Four kinds of cerium oxide nanoparticles coated, respectively, with Sodium bis(2-ethylhexyl) sulfosuccinate (AOT), cetyltrimethyl ammonium bromide (CTAB), poly vinyl pyrrolidone (PVP) and those (naked) without surface coating were prepared using chemical method. The particle sizes were identified to be 2 similar to 3 nm by using transmission electron microscope (TEM) and X-ray diffraction (XRD). Mixed valences of Ce3+ and Ce4+ were detected by X-ray absorption near-edge-structure (XANES) spectra. Extended X-ray absorption. ne structure (EXAFS) spectra of Ce L-3-edge were fitted with a core-shell model. The core parts are almost the same as bulk CeO2 with Ce4+ characteristic, however their shell parts change with surface coatings. The local atomic structures at shell parts (surface) and the contents and thicknesses of the shell parts were evaluated. The averaged Ce-O bond lengths at surface are changed from 2.504 angstrom (AOT), 2.568 angstrom (PVP), 2.628 angstrom (CTAB) to 2.634 angstrom (naked). The contents of surface are changed from 49% (AOT), 15% (PVP), 19% (CTAB) to 15% (naked). The results demonstrate that surface coatings have different influences on the surfaces of cerium oxide nanoparticles. A detailed discussion is given in this paper.