A large electric field is typically present in anodic or passive oxide films. Stresses induced by such a large electric field are critical in understanding the breakdown mechanism of thin oxide films and improving their corrosion resistance. In this work, we consider electromechanical coupling through the electrostrictive effect. A continuum model incorporating lattice misfit and electric field-induced stresses is developed. We perform a linear stability analysis of the full coupled model and show that, for typical oxides, neglecting electrostriction underestimates the film’s instability, especially in systems with a large electric field. Moreover, a region where electrostriction can potentially provide a stabilizing effect is identified, allowing electrostriction to enhance corrosion resistance. We identified an equilibrium electric field intrinsic to the system and the corresponding equilibrium film thickness. The film’s stability is very sensitive to the electric field: a 40 percent deviation from the equilibrium electric field can change the maximum growth rate by nearly an order of magnitude. Moreover, our model reduces to classical morphological instability models in the limit of misfit-only, electrostatic-only, and no-electrostriction cases. Finally, the effect of various parameters on the film’s stability is studied.

中文翻译：

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电致伸缩薄膜的形态稳定性

大电场通常存在于阳极或钝化氧化膜中。如此大的电场引起的应力对于理解薄氧化膜的击穿机制和提高其耐腐蚀性至关重要。在这项工作中，我们通过电致伸缩效应考虑机电耦合。开发了包含晶格失配和电场诱导应力的连续体模型。我们对全耦合模型进行了线性稳定性分析，结果表明，对于典型的氧化物，忽略电致伸缩会低估薄膜的不稳定性，特别是在具有大电场的系统中。此外，还确定了电致伸缩可能提供稳定作用的区域，从而允许电致伸缩增强耐腐蚀性。我们确定了系统固有的平衡电场和相应的平衡膜厚度。薄膜的稳定性对电场非常敏感：偏离平衡电场 40% 就会使最大生长速率改变近一个数量级。此外，我们的模型在仅失配、仅静电和无电致伸缩情况的限制下简化为经典形态不稳定模型。最后，研究了各种参数对薄膜稳定性的影响。