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

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