Microstructure of ZrO2–CeO2 hetero-multi-layer films grown on YSZ substrate
Microstructure of ZrO2–CeO2 hetero-multi-layer films grown on YSZ substrate
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DOI：
10.1016/j.actamat.2005.01.003
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发表时间：
2005-04
期刊：
影响因子：
9.4
通讯作者：
Chong-Min Wang;S. Azad;V. Shutthanandan;D. Mccready;C. Peden;L. Saraf;S. Thevuthasan
中科院分区：
文献类型：
--
作者：
Chong-Min Wang;S. Azad;V. Shutthanandan;D. Mccready;C. Peden;L. Saraf;S. Thevuthasan
采用氧等离子体辅助分子束外延技术，在氧化钇稳定的氧化锆衬底上生长了纯的氧化锆膜和氧化铈多层膜。用X射线衍射仪、常规和高分辨电子显微镜、电子能量损失谱、能量色散X射线元素图、选区电子衍射和动态电子衍射计算对薄膜的微观结构进行了分析。沉积的纯CeO2层以立方萤石结构存在，而ZrO2层相对于CeO2层表现出良好的外延取向。然而，在薄膜的选区电子衍射图上观察到了明显的(奇、奇、偶)型禁带衍射斑。暗场成像清楚地表明，这些被禁止的衍射点是由氧化锆层单独贡献的。基于氧沿c轴移动的单位四方相(空间群P42/NMC)的动态电子衍射计算与实验图样不符。相反，根据氧亚晶格沿〈111〉移动的立方结构(空间群P4‘3m)计算的衍射图与实验数据相吻合。在薄膜生长过程中引入了氧从理想位置(1/4，1/4，1/4)的位移。
Multi-layer films of pure ZrO2and CeO2were grown using oxygen plasma assisted molecular beam epitaxy on yttria stabilized zirconia substrates. The microstructure of the film was analyzed using X-ray diffraction, conventional and high-resolution transmission electron microscopy, electron energy-loss spectroscopy, energy dispersive X-ray elemental mapping, selected area electron diffraction, and dynamical electron diffraction calculations. The deposited pure CeO2layers exist in the cubic fluorite structure, and the ZrO2layers show a good epitaxial orientation with respect to the CeO2layers. However, distinctive forbidden diffraction spots of (odd, odd, even) type were observed on the selected area electron diffraction patterns of the film. Dark-field imaging clearly reveals that these forbidden diffraction spots were contributed solely by the ZrO2layers. Dynamical electron diffraction calculation based on the tetragonal phase of unity tetragonality (space group P42/nmc) with oxygen displaced along the c-axis does not match with the experimental pattern. Instead, a diffraction pattern calculated based on a cubic structure (space group P4¯3m) for which the oxygen sub-lattice was displaced along the 〈111〉 matches with the experimental data. It is further suggested that the displacement of the oxygen from the ideal (1/4, 1/4, 1/4) position was introduced during the film growth process.