Abstract High-index-oriented epitaxial ferroelectric films have recently attracted great attention due to their emergent functional properties related to the multi-domain structures. Here, the equilibrium phases and domain structures in (111)-oriented ferroelectric PbTiO3 films were investigated via phase-field simulations and the misfit strain-temperature equilibrium phase diagram was constructed. It was found that the epitaxial strain can effectively control the orientations of polarization vectors, which uniquely determine the domain variant patterns, domain wall orientations and densities. In particular, two types of tetragonal-like domain patterns can form under different strains with their distinct structural characteristics, ferroelectric properties and thermal conductivities. These results provide guidance for interpreting and understanding experimental data as well as designing of (111)-oriented ferroelectric films with specified domain structures and properties.

中文翻译：

---

(111)取向铁电PbTiO3薄膜中多畴结构的错配应变-温度相图

摘要 高折射率取向外延铁电薄膜由于其与多畴结构相关的新兴功能特性，最近引起了极大的关注。在这里，通过相场模拟研究了（111）取向铁电 PbTiO3 薄膜中的平衡相和畴结构，并构建了失配应变-温度平衡相图。结果表明，外延应变可以有效地控制极化矢量的方向，独特地决定了畴变图案、畴壁方向和密度。特别是，在不同的应变下可以形成两种类型的四方晶畴图案，它们具有不同的结构特征、铁电特性和热导率。