The characteristic functionality of ferroelectric materials is due to the symmetry of their crystalline structure. As such, ferroelectrics lend themselves to design approaches that manipulate this structural symmetry by introducing extrinsic strain. Using in situ dark-field X-ray microscopy to map lattice distortions around deeply embedded domain walls and grain boundaries in BaTiO₃, we reveal that symmetry-breaking strain fields extend up to several micrometres from domain walls. As this exceeds the average domain width, no part of the material is elastically relaxed, and symmetry is universally broken. Such extrinsic strains are pivotal in defining the local properties and self-organization of embedded domain walls, and must be accounted for by emerging computational approaches to material design.

铁电材料的特征功能性是由于其晶体结构的对称性。这样，铁电体便适合于设计通过引入外在应变来操纵这种结构对称性的方法。使用原位暗场X射线显微镜绘制深埋的畴壁和BaTiO _3中晶界周围的晶格畸变，我们揭示了对称破坏应变场从畴壁延伸到几微米。当超过平均域宽度时，材料的任何部分都不会弹性松弛，并且对称性通常会破坏。此类外在应变对于定义嵌入式畴壁的局部特性和自组织至关重要，必须通过新兴的材料设计计算方法来解决。