Crystal structure and non-stoichiometry of cerium brannerite: Ce0.975Ti2O5.95
Crystal structure and non-stoichiometry of cerium brannerite: Ce0.975Ti2O5.95
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DOI：
10.1016/j.jssc.2012.03.057
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发表时间：
2012-08-01
影响因子：
3.3
通讯作者：
Hyatt, N. C.
中科院分区：
文献类型：
--
作者：
Stennett, M. C.;Freeman, C. L.;Hyatt, N. C.
由高分辨中子粉末衍射数据(空间群C2/m，a=119.230(1)埃，b=3.75287(6)埃，c=6.8852(1)埃，β=6.8852(1)埃)的Rietveld分析确定了Ce0.975Ti2O5.95的晶体结构。Rietveld分析和缺陷能计算结合相图的仔细研究证实了Ce和O空位的存在。氧空位在O1位的形成，被Ce空位补偿，缓解了相当大的库仑排斥力，从而缓解了与形成相邻TiO6多面体共同边缘的短O1-O1接触相关的结构应变。根据对21个晶体结构的分析，考虑Ce0.975Ti2O5.95中Ce4+的键价和，得到参考键长度的修正值r(0)=2.098+/-0.039埃。(C)2012 Elsevier Inc.保留所有权利。
The crystal structure of cerium brannerite, Ce0.975Ti2O5.95, was determined from Rietveld analysis of high resolution neutron powder diffraction data (space group C2/m, a=9.8320(1) angstrom, b=3.75287(6) angstrom, c=6.8852(1) angstrom, beta=119.230(1)degrees). The presence of both cerium and oxygen vacancies was confirmed from Rietveld analysis and defect energy calculations, combined with careful investigation of the phase diagram. Formation of oxygen vacancies at the O1 site, charge compensated by Ce vacancies, relieves considerable Coulombic repulsion and hence structural strain associated with short O1-O1 contacts forming the shared edge of neighbouring TiO6 polyhedra. Consideration of the bond valence sum of Ce4+ in Ce0.975Ti2O5.95 afforded a revised value of the r(0)=2.098 +/- 0.039 angstrom for the reference bond length, based on analysis of 21 crystal structures mined from the ICSD. (C) 2012 Elsevier Inc. All rights reserved.