Defect characterization in CeO2−x at elevated temperatures—II: Neutron diffraction
Defect characterization in CeO2−x at elevated temperatures—II: Neutron diffraction
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高温下 CeO2−x 的缺陷表征—II：中子衍射
DOI：
10.1016/0022-3697(76)90030-5
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发表时间：
1976
影响因子：
2.1
通讯作者：
M. Mueller
中科院分区：
文献类型：
--
作者：
J. Faber;M. Seitz;M. Mueller
多晶 CeO/sub 2-x/（0 等于或小于 x 等于或小于 0.21）已在 900/sup 0/C 下通过中子衍射进行了检查，以表征造成非化学计量的主要原子点缺陷。通过将氧分压调节在1和10/sup -21/atm之间来控制化学计量。当 x 等于或小于 0.11 时，通过假设氧亚晶格上的缺陷随机分布，可以获得良好的一致性（剩余等于或小于 1.0%）。从中子数据分析中获得的空位浓度与热重测定一致。在 x 的这个区域内，阳离子和阴离子的温度因子都随着空位浓度的增加而增加，这意味着原子的均方根 (r.m.s.) 位移更大。然而，当 x 大于 0.11 时，中子数据分析表明阴离子振动幅度比接近化学计量的组合物更小，并且伴随着氧原子平衡位置的移动。还考虑了非简谐热运动的影响，但仅靠它无法解释中子数据。本研究的结果与之前的 X 射线实验有很好的相关性。
Polycrystalline CeO/sub 2-x/ (0 equal to or less than x equal to or less than 0.21) has been examined at 900/sup 0/C by means of neutron diffraction to characterize the predominant atomic point defects responsible for nonstoichiometry. The stoichiometry was controlled by adjusting the oxygen partial pressure between 1 and 10/sup -21/ atm. For x equal to or less than 0.11, good agreement (residual equal to or less than 1.0 percent) is obtained by assuming a random distribution of defects on the oxygen sublattice. Vacancy concentrations obtained from the neutron-data analysis are in agreement with thermogravimetric determinations. Over this region of x, the temperature factors of both the cation and anion increase with an increase in vacancy concentration, which implies greater root-mean-square (r.m.s.) displacement of the atoms. However, for x greater than 0.11, the analysis of the neutron data indicates a smaller anion vibrational amplitude than in the near-stoichiometric compositions and is accompanied by a shift in the equilibrium position of the oxygen atoms. The effect of anharmonic thermal motion has also been considered, but alone, cannot explain the neutron data. The results of the present study correlate well with the previous x-ray experiment.