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首页> 外文期刊>Physical review >Evolution of the local structure at the phase transition in CeO_2-Gd_2O_3 solid solutions
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Evolution of the local structure at the phase transition in CeO_2-Gd_2O_3 solid solutions

机译:CeO_2-Gd_2O_3固溶体相变过程中局部结构的演化

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摘要

We investigated the local environment of the Ce and Gd ions in one of the most important oxygen ion conductors, the CeO_2-Gd_2O_3 solid solution, using L_III edge extended x-ray absorption fine structure (EXAFS) spectroscopy and x-ray absorption near edge spectroscopy (XANES). The average Gd-O distance, as deduced by EXAFS, decreases gradually with increasing Gd content, whereas a sharp decrease in the average Ce-O distance occurs at 25 mol% Gd, accompanying the appearance of structural features characteristic of double fluorite symmetry. An abrupt change in the local environment of Ce, rather than of Gd, is also supported by the XANES spectra. Efforts at stabilizing the oxygen conducting Fm-3m phase in CeO_2-Gd_2O_3 solid solutions should therefore concentrate on tailoring the local environment of the Ce ion. We further suggest that our data may provide an explanation for the recently discovered giant electrostriction effect in Ce_(0.8)Gd_(0.2)O_(1.9). Since this composition is at the limit of stability of the fluorite phase, local distortions in Ce_(0.8)Gd_(0.2)O_(1.9) may be modulated by an external electric field more readily than those of the other solid solutions.
机译:我们使用L_III边缘扩展X射线吸收精细结构(EXAFS)光谱和X射线近边缘吸收光谱技术研究了最重要的氧离子导体之一CeO_2-Gd_2O_3固溶体中Ce和Gd离子的局部环境(XANES)。由EXAFS推算出的平均Gd-O距离随着Gd含量的增加而逐渐减小,而平均Ce-O距离在25 mol%Gd时出现急剧下降,并伴有双重萤石对称特征的结构特征的出现。 XANES光谱也支持Ce而不是Gd的局部环境的突然变化。因此,在CeO_2-Gd_2O_3固溶体中稳定氧传导Fm-3m相的努力应集中于调整Ce离子的局部环境。我们进一步建议,我们的数据可能为最近发现的Ce_(0.8)Gd_(0.2)O_(1.9)中的巨大电致伸缩效应提供了解释。由于该组成处于萤石相稳定性的极限,因此,Ce_(0.8)Gd_(0.2)O_(1.9)的局部变形比其他固溶体更容易受到外部电场的调制。

著录项

  • 来源
    《Physical review》 |2013年第5期|054101.1-054101.5|共5页
  • 作者单位

    Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel;

    Physics Department, Yeshiva University, 245 Lexington Avenue, New York, New York 10016, USA;

    Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel;

    Chemistry Division, Bhabha Atomic Research Center, Mumbai, India;

    Chemical Research Support Unit, Weizmann Institute of Science, Rehovot, Israel;

    Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel;

    Chemistry Division, Bhabha Atomic Research Center, Mumbai, India;

    Physics Department, Yeshiva University, 245 Lexington Avenue, New York, New York 10016, USA;

    Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel;

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  • 正文语种 eng
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  • 关键词

    solid-oxidefuelcells(SOFC);

    机译:固体氧化物燃料电池(SOFC);

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