Marchbank Huw R, Clark Adam H, Hyde Timothy I, Playford Helen Y, Tucker Matthew G, Thompsett David, Fisher Janet M, Chapman Karena W, Beyer Kevin A, Monte Manuel, Longo Alessandro, Sankar Gopinathan
Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK.
Johnson Matthey Technology Centre, Blount's Court, Sonning Common, Reading, RG4 9NH, UK.
Chemphyschem. 2016 Nov 4;17(21):3494-3503. doi: 10.1002/cphc.201600697. Epub 2016 Sep 20.
The structure of several nano-sized ceria, CeO , systems was investigated using neutron and X-ray diffraction and X-ray absorption spectroscopy. Whilst both diffraction and total pair distribution functions (PDFs) revealed that in all of the samples the occupancy of both Ce and O are very close to the ideal stoichiometry, the analysis using Reverse Monte Carlo technique revealed significant disorder around oxygen atoms in the nano-sized ceria samples in comparison to the highly crystalline NIST standard. In addition, the analysis revealed that the main differences observed in the pair correlations from various X-ray and neutron diffraction techniques were attributable to the particle size of the CeO prepared by the reported three methods. Furthermore, detailed analysis of the Ce L - and K-edge EXAFS data support this finding; in particular the decrease in higher shell coordination numbers with respect to the NIST standard, is attributed to differences in particle size.
利用中子和X射线衍射以及X射线吸收光谱对几种纳米级二氧化铈（CeO₂）体系的结构进行了研究。虽然衍射和总对分布函数（PDF）均表明，所有样品中Ce和O的占有率都非常接近理想化学计量比，但与高度结晶的美国国家标准与技术研究院（NIST）标准相比，使用反向蒙特卡罗技术的分析表明，纳米级二氧化铈样品中氧原子周围存在明显的无序现象。此外，分析表明，各种X射线和中子衍射技术在对关联中观察到的主要差异归因于通过所报道的三种方法制备的CeO₂的粒径。此外，对Ce L-边和K-边扩展X射线吸收精细结构（EXAFS）数据的详细分析支持了这一发现；特别是相对于NIST标准，较高壳层配位数的降低归因于粒径的差异。
