The core structures of dislocations are crucial for understanding the plastic deformation mechanisms and the functional properties of materials. Here, we use the scanning transmission electron microscopy imaging techniques of high-resolution high angle annular dark field and integrated differential phase contrast to investigate the atomic structure of a pair of climb-dissociated $\frac{1}{2}a[01\overline{1}]$ dislocations in a bending-deformed relaxor ferroelectric Pb(In_1/2Nb_1/2)O₃–Pb(Mg_1/3Nb_1/3)O₃–PbTiO₃ single crystal. Cations at one dislocation core are found to arrange in the same way as the climb-dissociated $\frac{1}{2}a[01\overline{1}]$ dislocation core in SrTiO₃, while the other one is different. Oxygen depletion was observed at both dislocation cores. Geometric phase analysis of the lattice rotation shows opposite signs at both sides of the dislocations, demonstrating the strain gradient, which is known to give rise to flexoelectric polarization. Using the peak finding method, the polarization (a combination of ferroelectric and flexoelectric) around dislocations was mapped at the unit-cell scale. The polarization direction obtained is consistent with that predicted based on the flexoelectric effect in a perovskite oxide with [011] geometry. Head-to-head positively charged and tail-to-tail negatively charged domain walls were revealed based on the polarization map, suggesting a new way to stabilize charged domain walls via dislocations. A distinct dislocation core configuration has been observed, and a unit-cell scale polarization map helps understand the flexoelectric effects (coupling between strain gradient and polarization) around dislocations in a relaxor ferroelectric.

中文翻译：

---

弛豫铁电体PIN-PMN-PT中塑性变形产生的一对12a[011¯]位错核周围的原子坐标和极化图

位错的核心结构对于理解材料的塑性变形机制和功能特性至关重要。在这里，我们使用高分辨率大角度环形暗场和积分微分相差的扫描透射电子显微镜成像技术来研究一对爬离解的原子结构。$\frac{1}{2}\mathrm{一种}[01\overline{1}]$弯曲变形的弛豫铁电体 Pb(In _1/2 Nb _1/2 )O ₃ –Pb(Mg _1/3 Nb _1/3 )O ₃ –PbTiO ₃单晶中的位错。发现一个位错核心的阳离子以与爬离解离的相同方式排列$\frac{1}{2}\mathrm{一种}[01\overline{1}]$SrTiO _{3 中的}位错核，而另一个则不同。在两个位错核心处都观察到氧耗竭。晶格旋转的几何相位分析在位错的两侧显示相反的符号，表明应变梯度，这已知会引起弯曲电极化。使用寻峰方法，位错周围的极化（铁电和挠电的组合）被映射到晶胞尺度。获得的极化方向与基于具有[011]几何形状的钙钛矿氧化物中的挠曲电效应预测的极化方向一致。基于极化图揭示了头对头带正电荷和尾对尾带负电荷的畴壁，提出了一种通过位错稳定带电畴壁的新方法。已观察到明显的位错核心配置，