0D Bismuth(III)-Based Hybrid Ferroelectric: Tris(acetamidinium) Hexabromobismuthate(III)

Abstract

Ferroelectric properties of haloantimonates­(III) and halobismuthates­(III) have been detected for as much as 40 structures belonging to 7 different types of anionic networks, with RMX4, R2MX5, R3M2X9, and R5M2X11 stoichiometries being the most frequently reported to host these properties. We report on the first ferroelectric of the halobismuthate­(III) family with a R3MX6 stoichiometry, that is, tris­(acetamidinium)­hexabromobismuthate­(III), (CH3C­(NH2)2)3[BiBr6] (ABB), characterized by a one-component organic network. While the stoichiometry and crystal packing of ABB might seem uncomplicated, the temperature-resolved structural and spectroscopic studies paint a different picture in which rich polymorphism in the solid state occurs between tetragonal (paraelastic) and triclinic (ferroelastic) crystal phases: I (P42/n) → II (P1̅) at 272/277 K (cooling/heating), II (P1̅) → III (P1̅) at 207 K, and III (P1̅) → IV (P1) at 98/127 K. The ferroelectric properties of phase IV have been confirmed by the pyroelectric current and hysteresis loop measurements; additionally, the acentric symmetry has been further supported by second harmonic generation measurements. Crystallographic analysis of phase III reveals the antiparallel alignment of acetamidinium dipoles, pointing to the antiferrroelectric nature of this phase. In turn, the character of the ferroelectric transition (III → IV) should be considered as “displacive” for both cationic and anionic substructures.) In this report, we also explore the two-photon absorption property of ABB at 800 nm, a property that is unexplored for any halobismuthate­(III) thus far. We also present periodic ab initio calculations for ABB crystals. The Berry-phase approach at the Hartree–Fock and density functional theory (DFT-D3) method levels is employed for spontaneous polarization calculations. The origin of ferroelectric polarization is studied using DFT-D3 and RHF electronic structure calculations, emphasizing the relationship between P s and the relative orientation of organic/inorganic components.

Ferroelasticity in Organic–Inorganic Hybrid Perovskites

“…Another Bi-based 0D organic inorganic hybrid perovskite, (CH 3 C(NH 2 ) 2 ) 3 [BiBr 6 ], which takes the rare A 3 BX 6 -type reported by Piecha-Bisiorek group. [61] As shown in Figure 4b, bismuthate(III) materials comprising isolated/discrete [MX 6 ] 3À framework anions are quite common, yet the ferroelastics of them were reported rarely. The 0D (CH 3 C(NH 2 ) 2 ) 3 [BiBr 6 ] is a multiferroic (ferroelectric and ferroelastic) compound, which undergoes from P1 to P � 1 to P � 1 to P4 2 /n space group at 127 K, 207 K, and 277 K, respectively.…”

“…Another Bi‐based 0D organic inorganic hybrid perovskite, (CH 3 C(NH 2 ) 2 ) 3 [BiBr 6 ], which takes the rare A 3 BX 6 ‐type reported by Piecha–Bisiorek group [61] . As shown in Figure 4b, bismuthate(III) materials comprising isolated/discrete [MX 6 ] 3− framework anions are quite common, yet the ferroelastics of them were reported rarely.…”

Optically Controlled Polarization Switching in an Organic Ferroelectric with Light- and Temperature-Triggered Phase Transitions

“…During the early pandemic, ferroelectric materials, represented by BaTiO 3 , as an “all-round player” have played a crucial role in this battle for the production of masks, ventilators, ultrasonic medical equipment, and other medical supplies. , Ferroelectrics also have broad applications in nonvolatile memories, capacitors, sensors, infrared detectors, and so on, owing to their various functional properties such as ferroelectricity, dielectricity, piezoelectricity, pyroelectricity, etc. − The most intrinsic property of ferroelectrics is that spontaneous polarization can be electrically switched and reoriented by the application of an external electric field. , In addition to the traditional external stimuli of the electric field, it has been found that polarization switching in some ferroelectrics can be achieved by mechanical stress, chemical environment, and light. − Among them, light is very attractive as a noncontact and noninvasive means for remote control of ferroelectric polarization toward developing future photocontrolled ferroelectric devices, and some progress has been made in switching polarization optically. − For instance, Yang and Alexe reported the optically controlled switching of ferroelectric domains in BiFeO 3 realized by the mediation of the photovoltaic effect . Optically controlled ferroelectric polarization has also been obtained in LiNbO 3 and BaTiO 3 through a light-induced thermal effect and stress change, respectively. , However, so far, only the optical control of ferroelectric polarization has been mainly studied in these classical inorganic ferroelectrics, in which the optically controlled polarization responses are basically realized by the mediation of light-induced photovoltaic effect, thermal effect, and stress change, and not the intrinsic photoinduced structural phase transition. − Although molecular ferroelectrics including the organic and organic–inorganic ones have gained tremendous interest in recent years because of the characteristics of easy processing, light weight, flexibility, and biocompatibility for low-cost, portable, and wearable ferroelectric devices, − optically controlled polarization switching is rarely found in molecular ferroelectrics.…”

Supramolecular Diiodine-Bromostannate(IV) Complexes: Narrow Bandgap Semiconductors

“…Metal halide complexes, or halometalates, represent the class of coordination compounds which, apart from fundamental interest (in particular, related to structural chemistry), attracts attention due to numerous areas of materials science where they can be applied. Those include design of ferroelectric and ferroelastic materials [1][2][3][4][5], photocatalysis [6][7][8], luminescence [9][10][11][12][13][14][15], photochromism [16,17], etc. However, the most prominent area is photovoltaics.…”