铁电材料中编织畴形成的力学相场建模
Mechanistic Phase-Field Modelling of Woven-Domain Formation in Ferroelectric Material
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中文总结 AI 辅助
本研究通过无量纲相场框架，结合多物理相互作用与三维扩展模型，揭示缓慢冷却为铁电材料编织畴拓扑选择提供动力学窗口，且模型结果对数值参数变化具鲁棒性。
中文摘要 AI 辅助
近期一项实验研究报道，在通过铁电相变缓慢冷却块状KTN:Li时，会自发形成三维铁电编织畴结构。本研究开发了无量纲相场框架，以探究该状态出现的物理可行路径：首先构建大面积二维模型，结合一阶铁电热力学、静电与弹性相互作用、成分调制及有效电荷屏蔽，解析与冷却速率相关的受挫交叉前驱体形成；缓慢冷却会产生大量与电荷相关的持久交叉结构，而快速冷却路径则不会。随后扩展为三维模型，引入立方梯度各向异性、 flexoelectric耦合及应变梯度正则化，探究平面前驱体是否能形成真实编织拓扑；在研究的无量纲参数范围内，缓慢冷却会使交叉畴壁族间出现明确的几何分离与深度序交换，快速冷却路径则无此现象，该差异在独立模拟实现中可重复，且对时间步长优化和计算域尺寸变化具有鲁棒性。模拟表明，缓慢冷却为拓扑选择提供了动力学窗口，全局电荷弛豫可与存活交叉点处的强局域电荷浓度共存；该模型未针对KTN:Li的材料特定系数校准，也未复现实验观测到的低温下编织态消失现象。
英文摘要
A recent experimental study reports the spontaneous formation of a three-dimensional woven ferroelectric domain fabric in bulk KTN:Li during sufficiently slow cooling through the ferroelectric transition. The present work develops a nondimensional phase-field framework to examine a physically plausible route by which such a state can emerge. A large-area two-dimensional model first resolves the cooling-rate-dependent formation of a frustrated crossing precursor by combining first-order ferroelectric thermodynamics, electrostatic and elastic interactions, compositional modulation, and effective charge screening. Slow cooling produces a persistent population of charge-associated crossings, whereas the corresponding fast-cooling pathway does not. A three-dimensional extension then incorporates cubic gradient anisotropy, flexoelectric coupling, and strain-gradient regularization to examine whether the planar precursor can develop a genuine woven topology. Within the explored nondimensional parameter regime, slow cooling produces a directly resolved geometrical separation and exchange of depth ordering between the intersecting wall families, whereas the corresponding fast-cooling pathway does not. This distinction is reproduced across independent realisations and remains robust to timestep refinement and changes in computational domain size. The simulations suggest that slow cooling provides a kinetic window for topological selection and that global charge relaxation can coexist with strong local charge concentration at surviving crossings. The model is not calibrated to material-specific KTN:Li coefficients and does not reproduce the experimentally observed low-temperature disappearance of the woven state.
