Materials Physics Department, Sandia National Laboratories, Livermore, California 94551, USA.
J Chem Phys. 2013 Sep 21;139(11):114703. doi: 10.1063/1.4820826.
We determine the atomic structure of the (111) surface of an epitaxial ceria film using low-energy electron diffraction (LEED). The 3-fold-symmetric LEED patterns are consistent with a bulk-like termination of the (111) surface. By comparing the experimental dependence of diffraction intensity on electron energy (LEED-I(V) data) with simulations of dynamic scattering from different surface structures, we find that the CeO2(111) surface is terminated by a plane of oxygen atoms. We also find that the bond lengths in the top few surface layers of CeO2(111) are mostly undistorted from their bulk values, in general agreement with theoretical predictions. However, the topmost oxygen layer is further from the underlying cerium layer than the true bulk termination, an expansion that differs from theoretical predictions.
我们使用低能电子衍射（LEED）确定了外延氧化铈薄膜的（111）表面的原子结构。具有 3 重对称性的 LEED 图案与（111）表面的类似体相的终止相一致。通过将实验上衍射强度对电子能量的依赖关系（LEED-I(V)数据）与来自不同表面结构的动态散射的模拟进行比较，我们发现 CeO2(111)表面由氧原子平面终止。我们还发现，CeO2(111)的表面几个顶层的键长大多数与其体相值没有明显的扭曲，这与理论预测基本一致。然而，最顶层的氧层比真实的体相终止离下面的铈层更远，这种膨胀与理论预测不同。
