AI 中文总结
本研究揭示了反铁电PbZrO₃中由八面体倾斜驱动铁电性的机制，发现了对称性主导的竞争性非本征铁电性途径，证实了类Pmc2₁结构的存在，对反铁电材料具有重要意义。
AI 中文摘要
我们揭示了原型反铁电材料PbZrO₃中铁电性的一种由倾斜驱动的机制。具体而言，向反铁电Pbam相中引入额外的八面体倾斜，会打破强制使反向偶极子相等的对称性约束，将补偿性的“↑↑↓↓”非极性构型转化为非补偿性的“↑↑↓↓”极性Pmc2₁相。第一性原理计算表明，Pmc2₁相在晶格收缩下变得稳定，且在有限温度下相较于竞争相获得的自由能优势不断增大。原子尺度成像直接证实了薄膜和单晶中存在类Pmc2₁结构。本研究确定了一种由对称性主导、动力学上易于实现的铁电性途径，确立了一种“竞争性”非本征铁电性，对反铁电材料具有广泛意义。
英文摘要
We reveal a tilt-driven mechanism for ferrielectricity in prototypical antiferroelectric PbZrO$_3$. Specifically, introducing an additional octahedral tilt into the antiferroelectric $Pbam$ phase breaks the symmetry constraint that enforces equal antiparallel dipoles, converting the compensated ``$\uparrow \uparrow \downarrow \downarrow$'' nonpolar configuration into an uncompensated ``$\uparrow \uparrow \downarrow \downarrow$'' polar $Pmc2_1$ phase. First-principles calculations show that the $Pmc2_1$ phase becomes stabilized under lattice contraction and gains increasing free-energy advantage over competing phases at finite temperatures. Atomic-scale imaging directly confirms the presence of $Pmc2_1$-like structures in thin films and single crystals. This work identifies a symmetry-governed, kinetically easily accessible pathway to ferrielectricity and establishes a form of ``competitive'' improper ferroelectricity, with broad implications for antiferroelectrics.
