The interplay and impact of strain and defect association on the conductivity of rare-earth substituted ceria
The interplay and impact of strain and defect association on the conductivity of rare-earth substituted ceria
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DOI：
10.1016/j.actamat.2018.12.058
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发表时间：
2019-03-01
期刊：
影响因子：
9.4
通讯作者：
Tuller, Harry L.
中科院分区：
文献类型：
--
作者：
Harrington, George F.;Sun, Lixin;Tuller, Harry L.
应变对稀土取代CeO2的离子导电性的影响已被广泛研究，但结果并不一致，主要集中在Gd或Sm取代CeO2等缺陷缔合最小的优化导体上。通过对脉冲激光沉积的外延薄膜进行热处理，我们系统地改变了应变，同时避免了界面或晶界效应的影响。平面电导的激活能随着压缩双轴应变的增加而增大，这与以前的计算和实验研究结果是一致的。这些结果为晶格应变对离子输运的影响提供了一个亟需的定量共识。此外，我们还证明了Yb替代CeO2的激活能变化大约是Gd或La替代时的三倍，这表明缺陷缔合起着重要的作用。这些结果对降低温度或环境温度下的离子传输具有重要意义，在这些温度下，由于应变引起的电导率变化，对于“未优化”的导体来说，可能比“优化”的导体大几个数量级。我们通过考虑这些材料中的缺陷相互作用并通过力场计算来合理地解释我们的结果。(C)2019 Acta Materialia Inc.由Elsevier Ltd.出版。保留所有权利。
The effects of strain on the ionic conductivity of rare-earth substituted CeO2 have been extensively studied, but the results have been inconsistent and focused upon the 'optimised' conductors such as Gd or Sm substituted CeO2 where defect association is minimised. By thermally annealing epitaxial films deposited by pulsed laser deposition, we varied the strain systematically, whilst avoiding any influence from interfacial or grain boundary effects. The activation energy of the in-plane conductivity was found to increase with increasing compressive biaxial strain, which was quantitatively in excellent agreement with previous computational and experimental studies. These results provide a much needed quantitative consensus on the effects of lattice strain on ionic transport. Furthermore, we demonstrate that the change in the activation energy for Yb-substituted CeO2 is around three times that for Gd or La substitutions for the same applied strain, indicating the important role played by defect association. These results have significant implications for ionic transport at reduced or ambient temperatures, where changes in conductivity due to strain may be several orders of magnitude larger for 'non-optimised' conductors compared with 'optimised' conductors. We rationalise our results by considering the defect defect interactions in these materials and through force-field calculations. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.