High-energy x-ray diffraction coupled with atomic pair distribution analysis and large-scale computer simulations are used to study the relationship between the local structure and piezoelectric response of an exemplary ferroelectric from the $\mathrm{BaTi}{\mathrm{O}}_3$ family where Ti is partially replaced by nonferroelectric Ce. Our results indicate that, likely, the increase in the piezoelectric response observed for Ce concentration <10% is due to an increased local rhombohedral distortion of the perovskite lattice. Despite a further increase in the distortion, the piezoelectric response for Ce concentration >10% decays quickly, likely because of rapidly increasing nonuniform strain fields due to the size mismatch between Ti- and Ce-centered octahedra and loss of electric dipoles due to the nonferroactivity of the latter. Thus, the transition between the observed two regimes of piezoelectric response does not appear to involve a crossing of a morphotropic phase boundary where the crystallographic symmetry changes abruptly but is likely to be percolative in nature. A similar behavior, referred to as tricritical phenomenon, is observed with other B-site substituted ferroelectrics from the $\mathrm{BaTi}{\mathrm{O}}_3$ family, indicating the presence of a common structural origin. Our results highlight the importance of chemical substitution-driven rhombohedral distortions in achieving control over the piezoelectric response of perovskite ferroelectrics, thereby providing a different perspective on the ongoing effort to improve their performance in practical applications.

中文翻译：

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具有增强的压电响应的B位取代钙钛矿铁电体的菱面体畸变和渗流现象

高能X射线衍射结合原子对分布分析和大规模计算机模拟被用来研究局部铁电体的示例性铁电体的局部结构和压电响应之间的关系。 $\mathrm{钡钛}{\mathrm{Ø}}_3$钛被非铁电铈部分替代的族。我们的结果表明，很可能在Ce浓度<10％时观察到的压电响应有所增加，这是由于钙钛矿晶格的局部菱面体变形增加所致。尽管畸变进一步增加，但Ce浓度> 10％时的压电响应会迅速衰减，这可能是由于以Ti和Ce为中心的八面体之间的尺寸失配以及非铁磁性导致的电偶极子损耗导致不均匀应变场迅速增加的缘故。后者。因此，观察到的两个压电响应状态之间的过渡似乎不涉及相变相边界的交叉，在该相交相中晶体对称性突然改变，但本质上可能是渗透性的。类似的行为$\mathrm{钡钛}{\mathrm{Ø}}_3$家族，表明存在共同的结构起源。我们的结果强调了化学取代驱动的菱面体畸变在控制钙钛矿铁电体的压电响应中的重要性，从而为正在进行的在实际应用中改善其性能的努力提供了不同的见解。