Center for Nanophase Materials Sciences, §Material Science and Technology Division, and ∥Chemical Sciences Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
Department of Materials Science and Engineering and ⊥The George Woodruff School of Mechanical Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
ACS Appl Mater Interfaces. 2018 Feb 7;10(5):4816-4823. doi: 10.1021/acsami.7b16900. Epub 2018 Jan 23.
Proton-conducting perovskites have been widely studied because of their potential application as solid electrolytes in intermediate temperature solid oxide fuel cells. Structural and chemical heterogeneities can develop during synthesis, device fabrication, or service, which can profoundly affect proton transport. Here, we use time-resolved Kelvin probe force microscopy, scanning transmission electron microscopy, atom probe tomography, and density functional theory calculations to intentionally introduce Ba-deficient planar and spherical defects and link the resultant atomic structure with proton transport behavior in both stoichiometric and nonstoichiometric epitaxial, yttrium-doped barium zirconate thin films. The defects were intentionally induced through high-temperature annealing treatment, while maintaining the epitaxial single crystalline structure of the films, with an overall relaxation in the atomic structure. The annealed samples showed smaller magnitudes of local lattice distortions because of the formation of proton polarons, thereby leading to decreased proton-trapping effect. This resulted in a decrease in the activation energy for proton transport, leading to faster proton transport.
质子导体钙钛矿因其在中温固体氧化物燃料电池中作为固体电解质的潜在应用而受到广泛研究。在合成、器件制造或使用过程中，可能会出现结构和化学不均匀性，这会深刻影响质子传输。在这里，我们使用时间分辨的 Kelvin 探针力显微镜、扫描透射电子显微镜、原子探针断层扫描和密度泛函理论计算，有意引入钡缺陷的平面和球形缺陷，并将所得的原子结构与化学计量和非化学计量外延、掺钇钡锆酸盐薄膜中的质子传输行为联系起来。通过高温退火处理，在保持薄膜的外延单晶结构的同时，整体弛豫原子结构，有意诱导缺陷。退火后的样品由于形成质子极化子，局部晶格畸变幅度较小，从而减少了质子捕获效应。这导致质子输运的激活能降低，从而导致质子输运加快。
