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首页> 外文期刊>Journal of Materials Chemistry, A. Materials for energy and sustainability >Interfacial stability and ionic conductivity enhanced by dopant segregation in eutectic ceramics: the role of Gd segregation in doped CeO2/CoO and CeO2/NiO interfaces
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Interfacial stability and ionic conductivity enhanced by dopant segregation in eutectic ceramics: the role of Gd segregation in doped CeO2/CoO and CeO2/NiO interfaces

机译：共晶陶瓷中掺杂剂偏析增强的界面稳定性和离子电导率：Gd偏析在掺杂CeO2 / CoO和CeO2 / NiO界面中的作用

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The conductivity of ceramic ionic materials is highly influenced by dopant segregation at the grain boundaries or interfaces, which usually induces a depletion of charge carriers by space charge effects. Hence, obtaining interfacial configurations that promote the formation of oxygen vacancies is highly desirable. In this paper we have combined high resolution electron microscopy (HREM), kelvin probe force microscopy (KPFM) and density functional theory (DFT) to elucidate the equilibrium state of CGO-CoO and CGO-NiO eutectic ceramics (CGO: cerium-gadolinium oxide). HREM proves that the interface is sharp, formed by a single common oxygen plane, and that in CGO-CoO the concentration of gadolinium ions at the interface is almost three times greater than in the bulk, while they distribute homogeneously in the CGO-NiO system. Accordingly, KPFM experiments suggest that interfacial ionic conductivity is much higher in CoO-CGO than in NiO-CGO. DFT demonstrates that Gd segregation in the CGO-CoO reduces the interface energy, contributing to its stability. The Gd-oxygen vacancy complexes compensate the interfacial ionic charge density discontinuity. Additionally, the induced local distortions around the defect release the strain associated with the lattice mismatch. Therefore, we show that in CGO-based eutectics the structure and ionicity of the constituent oxides are essential to promote the interface dopant segregation, indicating a new way to produce nanocomposites with enhanced interfacial ionic conductivity.
机译：陶瓷离子材料的电导率受到晶界或界面处的掺杂剂偏析的高度影响，这通常会通过空间电荷效应引起电荷载体的耗尽。因此，非常理想地获得促进氧空位的形成的界面配置。在本文中，我们已经组合了高分辨率电子显微镜（HREM），开尔文探针力学（KPFM）和密度泛函理论（DFT）来阐明CgO-CoO和Cg-Nio共晶陶瓷的平衡状态（CgO：氧化铈 - 富含铈 - 氧化钆） ）。 HREM证明界面是锋利的，由单个公共氧平面形成，并且在CGO-COO中，界面处的钆离子的浓度几乎大于散装量，而它们在Cg-NiO系统中均匀地分配。因此，KPFM实验表明，COO-CGO界面离子电导率远高于NIO-CGO。 DFT表明CGO-COO中的GD隔离降低了界面能量，促进其稳定性。 GD-氧空位复合物补偿界面离子电荷密度不连续性。另外，涉及缺陷周围的局部扭曲释放与晶格失配相关的应变。因此，我们表明，在基于CgO的共肠中，构成氧化物的结构和离子性对于促进界面掺杂剂的偏析是必不可少的，表明一种具有增强的界面离子导电性的纳米复合材料的新方法。

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