Pan Qiang, Xiong Yu-An, Sha Tai-Ting, Feng Zi-Jie, Zhou Ru-Jie, Yao Jie, Hu Hui-Hui, You Yu-Meng
Jiangsu Key Laboratory for Science and Applications of Molecular Ferroelectrics, Southeast University, Nanjing, 211189, P. R. China.
State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, P. R. China.
Adv Mater. 2025 Jan;37(1):e2410585. doi: 10.1002/adma.202410585. Epub 2024 Nov 5.
Multiferroics are appealing because of application potentials in data storage devices, sensors, transducers, and energy harvesters. Molecular multiferroics emerge as a promising alternative to inorganic multiferroics due to flexibility, light weight, low toxicity, solution processing, structural diversity, and chemical tunability. While researches have predominantly focused on perovskite structures, studies on molecular ionic multiferroics remain relatively limited. It is urgent to creatively build a novel platform for studying and developing the coupling and interaction between the stress, electricity, and magnetism. Knowing this, the work focuses on a novel organic-inorganic hybrid multiferroic N-ethyl-N-(fluoromethyl)-N-methylethylammonium tetrabromoferrate (III) showing coexisting magnetic and electric orderings. It undergoes antiferromagnetic, ferroelectric, and ferroelastic transitions. Notably, under a strain of 2.0%, the piezoelectric response increases tenfold, and the coercive field of ferroelectric polarization is reduced by half. The strain-induced enhancement of piezoelectricity is rarely reported in molecular multiferroics. Density functional theory is employed to predict that the mechanism of the large piezoelectric response under strain engineering is related to the cation rotation and phase switching between the stable phase and an energetically competitive metastable phase. This study creates a new paradigm to develop molecular multiferroics and future microelectronic devices for energy conversion.
多铁性材料因其在数据存储设备、传感器、换能器和能量收集器中的应用潜力而备受关注。分子多铁性材料由于具有柔韧性、重量轻、低毒性、可溶液加工、结构多样性和化学可调性等优点，成为无机多铁性材料的一种有前途的替代方案。虽然研究主要集中在钙钛矿结构上，但对分子离子多铁性材料的研究仍然相对有限。迫切需要创造性地构建一个新的平台，用于研究和开发应力、电和磁之间的耦合和相互作用。基于此，这项工作聚焦于一种新型的有机-无机杂化多铁性材料四溴铁酸（III）N-乙基-N-（氟甲基）-N-甲基乙铵，它同时存在磁有序和电有序。它经历反铁磁、铁电和铁弹转变。值得注意的是，在2.0%的应变下，压电响应增加了十倍，铁电极化的矫顽场降低了一半。应变诱导的压电增强在分子多铁性材料中很少被报道。采用密度泛函理论预测，应变工程下大压电响应的机制与阳离子旋转以及稳定相和能量上有竞争力的亚稳相之间的相转变有关。这项研究为开发分子多铁性材料和未来用于能量转换的微电子器件创造了一种新的范例。
