发表机构
Aiiso Yufeng Li Family Department of Chemical and Nano Engineering; Program in Materials Science and Engineering, University of California San Diego（加州大学圣地亚哥分校艾思友峰李家族化学与纳米工程系；材料科学与工程计划）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究以多晶SrTiO3为模型，发现大电流下阳极附近形成异常晶粒，其生长偏离经典动力学，机制涉及电场驱动的元素重分布、p-i-n结及氧化还原调控的晶界迁移。
AI 中文摘要
多晶SrTiO3被用作模型系统，研究在施加电流下的微观结构演化。在较大电流密度下，闪烧事件后，阳极附近形成排列良好、拉长的异常晶粒，这与先前报道的在可忽略电流下阴极侧增强的晶粒生长形成对比。异常晶粒的等效直径随时间线性增加，偏离经典的抛物线晶粒生长动力学。施加的电流驱动阳极附近的元素重新分布，产生一个富Ti区域，邻近一个向阴极迁移的富Sr带，异常晶粒从该带形核。像差校正扫描透射电子显微镜和电子能量损失谱揭示，富Ti体区内的快速移动晶界（GBs）富Sr、贫O、且Ti减少。基于Brouwer图的分析表明，在施加电场下形成了p-i-n区域。电子电流和离子电流在p-i和i-n结处的转换、场驱动的富Sr Ruddlesden-Popper相的析出和溶解，以及场驱动的Sr和O空位迁移，共同解释了元素重新分布和富Sr带的氧化还原调控迁移。移动结处的不完全氧化还原反应产生了移动的富Sr带，并生成局部还原环境，从而产生快速移动的、富Sr的、还原态晶界。这些发现揭示了电场驱动的缺陷介导的微观结构演化的新机制。
英文摘要
Polycrystalline SrTiO3 is employed as a model system to investigate microstructural evolution under applied electric currents. Under a substantial current density, well-aligned, elongated abnormal grains develop near the anode following a flash event, in contrast to previously reported cathode-side enhanced grain growth under negligible currents. The equivalent diameter of the abnormal grains increases linearly with time, deviating from classical parabolic grain growth kinetics. The applied current drives elemental redistribution near the anode, producing a Ti-rich region adjacent to a Sr-rich belt that migrates toward the cathode, from which the abnormal grains nucleate. Aberration-corrected scanning transmission electron microscopy and electron energy-loss spectroscopy reveal that the fast-moving grain boundaries (GBs) within the Ti-rich bulk region are Sr-enriched, O-depleted, and Ti-reduced. An analysis based on the Brouwer diagram suggests the formation of p-i-n regions under the applied electric field. Conversion between electronic and ionic currents at the p-i and i-n junctions, field-driven precipitation and dissolution of the Sr-rich Ruddlesden-Popper phase, and field-driven migration of Sr and O vacancies collectively explain the elemental redistribution and redox-modulated migration of the Sr-rich belt. Incomplete redox reactions at the moving junctions create the moving Sr-rich belt and generate a locally reducing environment, consequently producing fast-moving, Sr-rich, reduced GBs. These findings reveal new mechanisms of electric current-driven defect-mediated microstructural evolution.
