Ai Yong, Chen Xiao-Gang, Shi Ping-Ping, Tang Yuan-Yuan, Li Peng-Fei, Liao Wei-Qiang, Xiong Ren-Gen
Ordered Matter Science Research Center , Nanchang University , Nanchang 330031 , People's Republic of China.
Jiangsu Key Laboratory for Science and Applications of Molecular Ferroelectrics , Southeast University , Nanjing 211189 , People's Republic of China.
J Am Chem Soc. 2019 Mar 13;141(10):4474-4479. doi: 10.1021/jacs.9b00886. Epub 2019 Mar 5.
The past decade has witnessed much progress in designing molecular ferroelectrics, whose intrinsic mechanical flexibility, structural tunability, and easy processability are desirable for next-generation flexible and wearable electronic devices. However, an obstacle in expanding their promising applications in nonvolatile memory elements, capacitors, and sensors is effectively modulating the Curie temperature ( T). Here, taking advantage of fluorine substitution on the reported molecular ferroelectric, (pyrrolidinium)MnCl, we present enantiomeric perovskite ferroelectrics, namely, ( R) - and ( S) -3-(fluoropyrrolidinium)MnCl. The close van der Waal's radii and the similar steric parameters between H and F atoms ensure the minimum disruption of the crystal structure, while their different electronegativity and polarizability can trigger significant changes in the physical and chemical properties. As expected, the T gets successfully increased from 295 K in (pyrrolidinium)MnCl to 333 K in these two homochiral compounds. Such a dramatic enhancement of 38 K signifies an important step toward designing high- T molecular ferroelectrics. In the light of the conceptually new idea of fluorine substitution, one could look forward to a continuous succession of new molecular ferroelectric materials and technology developments.
在过去十年中，分子铁电体的设计取得了很大进展，其固有的机械柔韧性、结构可调性和易于加工性对于下一代柔性和可穿戴电子设备来说是非常理想的。然而，要将它们在非易失性存储元件、电容器和传感器等领域的应用前景进一步拓展，一个障碍是有效调节居里温度（T）。在此，利用在已报道的分子铁电体（吡咯烷鎓）MnCl上进行氟取代，我们展示了对映体钙钛矿铁电体，即（R）-和（S）-3-（氟吡咯烷鎓）MnCl。H和F原子之间相近的范德华半径和相似的空间参数确保了晶体结构的最小破坏，而它们不同的电负性和极化率能够引发物理和化学性质的显著变化。正如预期的那样，居里温度在（吡咯烷鎓）MnCl中为295K，而在这两种纯手性化合物中成功提高到了333K。38K的显著提升标志着朝着设计高居里温度分子铁电体迈出了重要一步。鉴于氟取代这一全新概念，人们可以期待新的分子铁电材料和技术发展不断涌现。
