Structure transformations and reducibility of nanocrystalline Ce_{1鈭?span style='font-style: italic'>x}Yb_xO_2鈭?x/2) mixed oxides

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• 作者：Ma艂gorzata A. Ma艂ecka^a ; ^b ; ^{M.Malecka@int.pan.wroc.pl} ; Juan J. Delgado^b ; ^{juanjose.delgado@uca.es} ; Leszek K臋pi艅ski^a ; Jose J. Calvino^b ; Serafin Bernal^b ; Ginesa Blanco^b ; Xiaowei Chen^b
• 关键词：Nanoparticle structure ; Ceria based oxides ; CeO2&ndash ; Yb2O3 ; HRTEM ; Images simulation
• 刊名：Catalysis Today
• 出版年：2012
• 期刊代码：13_09205861
• 类别：ce
• 出版时间：30 June, 2012
• 卷：187
• 期：1
• 页码：56-64
• 文件大小：1597 K

摘要

This work presents results of multitechnique (HRTEM, EDX, XRD, XPS, ICP, BET and EELS) studies on structure evolution of nanocrystalline ceria-based Ce_1鈭?em>xYb_xO_2鈭?x/2) mixed oxides with increasing Yb content. Nano-sized (鈭? nm) mixed oxides were prepared by precipitation in water-in-oil (W/O) microemulsion method. No phase separation or/and segregation were observed for studied samples after heating in oxygen up to 950 掳C. Realistic models of the intermediate structures (defected F- and C-type) for mixed oxides and mechanism of CeO₂ 鈫?#xA0;Ce_1鈭?em>xYb_xO_2鈭?x/2) 鈫?#xA0;Yb₂O₃ structural changes have been proposed and tested (HRTEM images and diffraction patterns simulation). Reducibility of Ce_1鈭?em>xYb_xO_2鈭?x/2) mixed oxides and its changes with increasing of Yb content was measured and correlated with the structure features. The highest reducibility of Ce ions was observed for Ce_0.5Yb_0.5O_1.75, which has a structure intermediate between F and C-type, with maximum number of defects and the highest average strain.