Song Xian-Jiang, Zhang Tie, Gu Zhu-Xiao, Zhang Zhi-Xu, Fu Da-Wei, Chen Xiao-Gang, Zhang Han-Yue, Xiong Ren-Gen
Jiangsu Key Laboratory for Science and Applications of Molecular Ferroelectrics, Southeast University, Nanjing 211189, People's Republic of China.
J Am Chem Soc. 2021 Apr 7;143(13):5091-5098. doi: 10.1021/jacs.1c00613. Epub 2021 Mar 23.
Solid-state molecular rotor-type materials such as host-guest inclusion compounds are very desirable for the construction of molecular ferroelectrics. However, they usually have a low Curie temperature () and uniaxial nature, severely hindering their practical applications. Herein, by regulating the anion to control "momentum matching" in the crystal structure, we successfully designed a high-temperature multiaxial host-guest inclusion ferroelectric [(MeO-CH-NH)(18-crown-6)][TFSA] (MeO-CH-NH = 4-methoxyanilinium, TFSA = bis(trifluoromethanesulfonyl)ammonium) with the Aizu notation of F. Compared to the parent uniaxial ferroelectric [(MeO-CH-NH)(18-crown-6)][BF] with a of 127 K, the introduction of larger TFSA anions brings a lower crystal symmetry at room temperature and a higher energy barrier of molecular motions in phase transition, giving [(MeO-CH-NH)(18-crown-6)][TFSA] multiaxial ferroelectricity and a high up to 415 K (above that of BaTiO). To our knowledge, such a record temperature enhancement of 288 K makes its the highest among the reported crown-ether-based ferroelectrics, giving a wide working temperature range for applications in data storage, temperature sensing, actuation, and so on. This work will provide guidance and inspiration for designing high- host-guest inclusion ferroelectrics.
诸如主客体包合物之类的固态分子转子型材料对于分子铁电体的构建非常理想。然而，它们通常具有较低的居里温度（）和单轴性质，严重阻碍了它们的实际应用。在此，通过调节阴离子来控制晶体结构中的“动量匹配”，我们成功设计了一种高温多轴主客体包合铁电体[(MeO-CH-NH)(18-冠-6)][TFSA]（MeO-CH-NH = 4-甲氧基苯胺鎓，TFSA = 双（三氟甲磺酰）铵），其爱知符号为F。与居里温度为127 K的母体单轴铁电体[(MeO-CH-NH)(18-冠-6)][BF]相比，引入更大的TFSA阴离子在室温下带来更低的晶体对称性以及相变中分子运动的更高能垒，赋予[(MeO-CH-NH)(18-冠-6)][TFSA]多轴铁电性以及高达415 K的居里温度（高于BaTiO的居里温度）。据我们所知，288 K的创纪录温度提升使其居里温度在已报道的基于冠醚的铁电体中最高，为数据存储、温度传感、驱动等应用提供了宽广的工作温度范围。这项工作将为设计高温主客体包合铁电体提供指导和启发。
