We report on our investigation of structural defect and strain formation in electrodegraded reduced and oxidized, Fe‐doped SrTiO₃ (Fe:STO) single crystals using optical second harmonic generation (SHG) and confocal Raman spectroscopy. SHG and Raman spectra reveal structural and electrochemical inhomogeneity resulting from the formation of Fe⁴⁺/oxygen ion and Fe³⁺/oxygen vacancy aggregation sites along the degraded anode and cathode interfaces, respectively. We show that mixed Fe³⁺/Fe⁴⁺ states and structural strain gradients are generated across the color fronts. These results, as well as oxygen sublattice differences between the anodic and cathodic bulk, present the color front as an interface between two dominant oxygen bonding distortions. The strain near the color front shows a strong dependence on oxygen vacancy concentration and diffusion within the crystals. Our characterization of structural and electrochemical changes due to electric field‐induced strain and oxygen vacancy migration advances knowledge of electrodegradation in perovskite‐based titanate single crystals.

中文翻译：

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氧空位迁移导致电梯度掺Fe SrTiO3晶体结构缺陷和应变的形成

我们报告了我们使用光学二次谐波（SHG）和共聚焦拉曼光谱对电还原的，氧化的，掺Fe的SrTiO ₃（Fe：STO）单晶进行结构缺陷和应变形成的研究。SHG和拉曼光谱揭示了分别沿降解的阳极和阴极界面形成Fe ⁴⁺ /氧离子和Fe ³⁺ /氧空位聚集位点导致的结构和电化学不均匀性。我们表明混合的Fe ³⁺ / Fe ⁴⁺状态和结构应变梯度是在整个彩色前沿上生成的。这些结果以及阳极体和阴极体之间的氧亚晶格差异，将颜色前沿呈现为两个主要的氧键畸变之间的界面。靠近颜色前沿的应变显示出对氧空位浓度和晶体内扩散的强烈依赖性。我们对由于电场引起的应变和氧空位迁移而引起的结构和电化学变化的表征，提高了钙钛矿基钛酸酯单晶中电沉积的知识。