论文标题
通过熵稳定，从杂种不当铁电的一阶到二阶相变
From first- to second-order phase transitions in hybrid improper ferroelectrics through entropy stabilisation
论文作者
论文摘要
在过去的几年中，对混合不当铁电（HIF）进行了深入研究，以了解其温度诱导的相变和铁电交换途径。在这里，我们报告了局部HIFS $ CA__ {3-X} SR_XTI_2O_7 $的一阶相转换途径的切换，该途径是由我们识别为与八面体倾斜和旋转的动态运动相关的各个相位的不同熵驱动的。对这类分层的钙钛矿中的过渡途径有更深入的了解，这些物理特性与特定的对称性和八面体旋转和倾斜失真相结合，例如超导性，负面热膨胀，快速电导率，快离子电导率，铁电性等于创建新颖的功能材料的重要步骤。
Hybrid improper ferroelectrics (HIFs) have been intensely studied over the last few years to gain understanding of their temperature induced phase transitions and ferroelectric switching pathways. Here we report a switching from first- to second-order phase transition pathway for topical HIFs $Ca_{3-x}Sr_xTi_2O_7$, which is driven by the differing entropies of the phases that we identify as being associated with the dynamic motion of octahedral tilts and rotations. A greater understanding of the transition pathways in this class of layered perovskites, which host many physical properties that are coupled to specific symmetries and octahedral rotation and tilt distortions -- such as superconductivity, negative thermal expansion, fast ion conductivity, ferroelectricity, among others -- is a crucial step in creating novel functional materials by design.
