Faculty of Chemistry, University of Wrocław, Wrocław 50-383, Poland.
Institute of Advanced Materials, Faculty of Chemistry, Wrocław University of Science and Technology, Wrocław 50-370, Poland.
J Phys Chem Lett. 2023 May 18;14(19):4524-4531. doi: 10.1021/acs.jpclett.3c00924. Epub 2023 May 9.
Halobismuthates(III) and haloantimonates(III) with the RMX chemical composition create a new and broadly unexplored class of ferroelectric compounds. In this paper, we report the haloantimonate(III) ferroelectric comprising an aromatic (1,2,4-triazolium) cation, i.e., (CNH)[SbBr] (). Temperature-resolved structural and spectroscopic studies indicate that undergoes two solid-solid phase transitions between tetragonal [4/ (I)] and monoclinic [2/ (II) and 2 (III)] phases. experiences a paraelectric-ferroelectric phase transition at 271/268 K (II-III) driven by "order-disorder" and "displacive" molecular mechanisms. The ferroelectric properties of phase III have been confirmed by hysteresis loop measurement, and additionally, the acentric order has been further supported by second-harmonic generation measurements. Insight into the molecular origins of the ferroelectric polarization was provided by periodic calculations using the Berry phase approach at the density functional theory (DFT-D3) method level employed for calculations of spontaneous polarization.
卤氧化铋（III）和卤氧化锑（III）具有 RMX 化学组成，构成了一类全新且广泛未被探索的铁电化合物。本文报道了一种卤氧化锑（III）铁电化合物，包含一个芳香族（1,2,4-三氮唑）阳离子，即 (CNH)[SbBr] ()。温度分辨结构和光谱研究表明，在四方相 [4/ (I)] 和单斜相 [2/ (II) 和 2 (III)] 之间存在两个固-固相变。在 271/268 K (II-III) 处，经历了由“有序无序”和“位移”分子机制驱动的顺电-铁电相变。通过滞后回线测量证实了相 III 的铁电性能，并且通过二次谐波产生测量进一步支持了非中心有序。通过使用密度泛函理论（DFT-D3）方法水平上的 Berry 相位方法进行周期性计算，提供了对铁电极化分子起源的深入了解，该方法用于计算自发极化。
