Ordered Matter Science Research Center, Nanchang University, Nanchang 330031, People's Republic of China.
Institute for Science and Applications of Molecular Ferroelectrics, Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Zhejiang Normal University, Jinhua 321004, People's Republic of China.
J Am Chem Soc. 2020 Jul 15;142(28):12486-12492. doi: 10.1021/jacs.0c05372. Epub 2020 Jun 30.
For a century ferroelectricity has attracted widespread interest from science and industry. Inorganic ferroelectric ceramics have dominated multibillion dollar industries of electronic ceramics, ranging from nonvolatile memories to piezoelectric sonar or ultrasonic transducers, whose polarization can be reoriented in multiple directions so that they can be used in the ceramic and thin-film forms. However, the realization of macroscopic ferroelectricity in the polycrystalline form is challenging for molecular ferroelectrics. In pursuit of low-cost, biocompatible, and mechanically flexible alternatives, the development of multiaxial molecular ferroelectrics is imminent. Here, from quinuclidinium perrhenate, we applied fluorine substitution to successfully design a multiaxial molecular ferroelectric, 3-fluoroquinuclidinium perrhenate ([3-F-Q]ReO), whose macroscopic ferroelectricity can be realized in both powder compaction and thin-film forms. The fluorination effect not only increases the intrinsic polarization but also reduces the coercive field strength. More importantly, it is also, as far as we know, the softest of all known molecular ferroelectrics, whose low Vickers hardness of 10.5 HV is comparable with that in poly(vinylidene difluoride) (PVDF) but almost 2 orders of magnitude lower than that in BaTiO. These attributes make it an ideal candidate for flexible and wearable devices and biomechanical applications.
一个世纪以来，铁电性一直引起科学界和工业界的广泛关注。无机铁电陶瓷已经主导了数十亿美元的电子陶瓷产业，从非易失性存储器到压电声纳或超声换能器，其极化可以在多个方向上重新定向，从而可以用于陶瓷和薄膜形式。然而，对于分子铁电体来说，在多晶形式中实现宏观铁电性具有挑战性。为了寻找低成本、生物相容性和机械柔韧性的替代品，多轴分子铁电体的发展迫在眉睫。在这里，我们从金纳灵过铼酸根中应用氟取代成功设计了一种多轴分子铁电体，3-氟金纳灵过铼酸根([3-F-Q]ReO)，其宏观铁电性可以在粉末压实和薄膜形式中实现。氟化效应不仅增加了固有极化，而且降低了矫顽场强度。更重要的是，据我们所知，它也是所有已知分子铁电体中最软的一种，其维氏硬度值 10.5HV 与聚偏二氟乙烯（PVDF）相当，但比钛酸钡低 2 个数量级。这些特性使其成为柔性和可穿戴设备以及生物力学应用的理想候选材料。
