揭示倾斜驱动的混合非本征铁电体中的结构异质性：空间分辨晶体学研究
Revealing tilt-driven structural heterogeneity in hybrid improper ferroelectrics by spatially-resolved crystallography
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中文总结 AI 辅助
本研究利用扫描三维X射线衍射技术，在混合非本征铁电体中揭示了畴壁的扩展结构，其宽度远超传统界面，并通过倾斜序参量的连续旋转形成四方中间态，为理解铁弹畴壁形成和铁电切换提供了微观机制。
中文摘要 AI 辅助
铁性氧化物中的畴壁可以承载与周围体相根本不同的涌现功能，使其微观结构成为理解和控制宏观行为的关键。我们使用扫描三维X射线衍射技术，在混合非本征铁电体Ca$_{2.15}$Sr$_{0.85}$Ti$_{2}$O$_{7}$中铁弹畴壁上，绘制了耦合八面体畸变模式的空间演化。通过将断层扫描重建与八面体旋转、倾斜及相关应变模式的对称性适应分析相结合，我们绘制了它们在体相晶体中单个畴壁上的空间演化。我们发现畴壁本质上是扩展的，其宽度远超传统Ising型铁性界面所预期的宽度。畴壁结构以倾斜序参量通过四方中间态的连续旋转为特征。这些结果为控制铁弹畴壁形成、铁电切换和畴壁处涌现功能的结构机制提供了新的微观见解。
英文摘要
Domain walls in ferroic oxides can host emergent functionalities that differ fundamentally from those of the surrounding bulk, making their microscopic structure central to understanding and controlling macroscopic behaviour. We use scanning three-dimensional X-ray diffraction to map the spatial evolution of coupled octahedral distortion modes across ferroelastic domain walls in the hybrid improper ferroelectric Ca$_{2.15}$Sr$_{0.85}$Ti$_{2}$O$_{7}$. By combining tomographic reconstruction with symmetry-adapted analysis of the octahedral rotation and tilt and associated strain modes, we map their spatial evolution across individual walls in the bulk crystal. We find that the walls are intrinsically extended, with widths far exceeding those expected for conventional Ising-like ferroic interfaces. The wall structure is characterised by a continuous rotation of the tilt order parameter through a tetragonal intermediate. These results provide new microscopic insight into the structural mechanisms governing ferroelastic wall formation, ferroelectric switching, and emergent functionality at domain walls.
发表机构
- University of Warwick（华威大学）
- European Synchrotron Radiation Facility（欧洲同步辐射装置）
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