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

Klaudia Mencel,Vasyl Kinzhybalo,Marek Drozd,Anna Piecha-Bisiorek,Przemysław Szklarz,Piotr Durlak,Jan K Zaręba,Ryszard Jakubas

doi:10.1021/acs.chemmater.1c01266

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 Ps and the relative orientation of organic/inorganic components.

Highlights

Hybrid materials with a rich solid-to-solid phase transition (PT) behavior attract widespread attention because of their high-profile applications in which they could be employed
With the use of the solid-state two-photon exited fluorescence (SSTPEF) technique,[53] we found that the value of two-photon brightness (σ2φ, the product of two-photon absorption cross section σ2 and quantum yield of luminescence φ) at 800 nm is ca. 5 × 10−4 GM per (CH3C(NH2)2)3[BiBr6] structural unit
The ferroelectric property is evidenced for dozens of haloantimonates(III) and halobismuthates(III), the bulk of which adapted R2MX5, R3M2X9, and R5M2X11 stoichiometries

Summary

INTRODUCTION

Hybrid materials with a rich solid-to-solid phase transition (PT) behavior attract widespread attention because of their high-profile applications in which they could be employed. Some of the most interesting examples are the dialkylammonium derivatives crystallizing in the polar space group R3c9,10 and allylammonium analogues characterized by a complex sequence of PTs and ferroelastic properties.[11,12] Within the R3MX6 subgroup, above-room-temperature (RT) switching of the second harmonic generation (SHG) response has been reported for (C4H16N3)[BiBr6] by Wu13 and visible luminescence for (C6H5−CH2NH3)3[MBr6] (M = Bi(III) and Sb(III)) by Chen.[14]. The first mononuclear halobismuthate(III) comprising two disparate organic cations has been reported by Wang et al.[15] in this case, the cationic substructure consists of two different moieties: one dimethylammonium (R′) and two benzylammonium (R′′) cations, whereas the anionic component consists of an isolated octahedral unit [BiBr6]3−. ABB is the first example of a “pure” organic−inorganic hybrid ferroelectric within halobismuthates(III) of the R3MX6 type of stoichiometry characterized by a one-component organic network. Experimental characterizations of ABB, focused primarily on the polar order of its lowest temperature phase, are further supported by periodic ab initio calculations of Ps by employing the Berry-phase (BP) approach at the Hartree−Fock (HF) and density functional theory (DFT-D3) method levels

EXPERIMENTAL SECTION

RESULTS AND DISCUSSION

CONCLUSIONS

■ ACKNOWLEDGMENTS

■ REFERENCES