Anions Distorting Triggering Ferroelectricity in a Molecular Crystal

• Published in: Chinese journal of chemistry 2022-09, Vol.40 (18), p.2226-2231
• Main Authors: Ye, Si‐Yu, Liu, Jing‐Yuan, Tong, Liang, Wang, Yan‐Ning, Wan, Min, Mensah, Abraham, Jiang, Xiao‐Fan, Li, Jun‐Yi, Chen, Li‐Zhuang
• Format: Article
• Language: English
• Subjects: Anions; Barium titanates; Cations; Crystals; Curie temperature; Design modifications; Design strategy; Ferroelectric materials; Ferroelectricity; Hysteresis loops; Molecular ferroelastic; Organic‐inorganic hybrid composites; Phase transitions; Tetrahedra
• ISSN: 1001-604X; 1614-7065
• DOI: 10.1002/cjoc.202200297

Comprehensive Summary Recently, molecular ferroelectrics have attracted more and more attention due to their structural diversity, low cost of manufacture, and environmental‐friendly processing. However, most of the design strategies for molecular ferroelectrics have focused on the selection and modification of cations, and the use of anions has been rarely reported. Here, introducing distorted [CuBr4]2– tetrahedra, we obtained a high curie temperature (Tc) ferroelectric, [cyclopentylammonium]2CuBr4, with a Tc as high as 393 K, and exceeding commercial and most of reported molecular ferroelectric BaTiO3 (393 K). Variable‐temperature hysteresis loop shows the nonlinear P‐E loop of the crystal under a wide temperature range. Variable‐temperature single‐crystal X‐ray diffraction revealed that the Aizu expression can be written as mmmFmm2. In short, this work will inspire more creative strategies by exploiting the tunability of the anion module. We present a new strategy for the design of molecular ferroelectric: Inducing ferroelectricity in phase transition compounds by introducing anions with different symmetries. Specifically, we have constructed a molecular ferroelectric (CPA)2CuBr4 with high Tc(393 K)and switchable dielectric properties using distorted [CuBr4]2– anion instead of orthotetrahedron [ZnBr4]2–.