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Oxygen Surface Exchange at Grain Boundaries of Oxide Ion Conductors

机译:氧化物离子导体晶界处的氧表面交换

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摘要

The role of grain boundaries on oxygen surface exchange in an oxide ion conductor is reported. Atomic-scale characterization of the microstructure and chemical composition near the grain boundaries of gadolinia-doped ceria (CDC) thin films show the segregation of dopants and oxygen vacancies along the grain boundaries using the energy dispersive spectroscopy in scanning transmission electron microscopy (STEM-EDS). Kelvin probe microscopy is employed to verify the charge distribution near grain boundaries and shows that the grain boundary is positively charged, indicating a high concentration of oxygen vacancies. AC impedance spectroscopy on polycrystalline CDC membranes with thin interfacial layers with different grain boundary densities at the cathodes demonstrated that the cells with higher grain boundary density result in lower electrode impedance and higher exchange current density. These experimental evidences clearly show that grain boundaries on the surface provide preferential reaction sites for facilitated oxygen incorporation into the CDC electrolyte.
机译:据报道,晶界在氧化物离子导体中氧表面交换上的作用。氧化g掺杂二氧化铈(CDC)薄膜晶界附近的微观结构和化学成分的原子尺度表征显示,使用扫描透射电子显微镜(STEM-EDS)中的能量色散谱,沿晶界的掺杂剂和氧空位偏析)。开尔文探针显微镜用于验证晶界附近的电荷分布,并显示晶界带正电,表明氧空位浓度很高。在阴极处具有不同晶界密度的薄界面层的多晶CDC膜上的交流阻抗谱表明,晶界密度较高的电池会导致较低的电极阻抗和较高的交换电流密度。这些实验证据清楚地表明,表面上的晶界为促进氧掺入CDC电解质提供了优先的反应部位。

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  • 来源
    《Advanced Functional Materials》 |2012年第5期|p.965-971|共7页
  • 作者单位

    Nanoscale Prototyping Laboratory Department of Mechanical Engineering Stanford University Stanford, CA 94305, USA,Laboratory of Electrochemical Interfaces, Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA;

    Department of Materials Science and Engineering Stanford University Stanford, CA 94305, USA;

    Department of Materials Science and Engineering Seoul National University Seoul, 151-742, South Korea;

    Nanoscale Prototyping Laboratory Department of Mechanical Engineering Stanford University Stanford, CA 94305, USA;

    Nanoscale Prototyping Laboratory Department of Mechanical Engineering Stanford University Stanford, CA 94305, USA;

    Department of Materials Science and Engineering Stanford University Stanford, CA 94305, USA;

    Nanoscale Prototyping Laboratory Department of Mechanical Engineering Stanford University Stanford, CA 94305, USA,Department of Materials Science and Engineering Stanford University Stanford, CA 94305, USA;

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