Intercalation-driven ferroelectric-to-ferroelastic conversion in a layered hybrid perovskite crystal

Abstract

Two-dimensional (2D) organic-inorganic hybrid perovskites have attracted intense interests due to their quantum well structure and tunable excitonic properties. As an alternative to the well-studied divalent metal hybrid perovskite based on Pb2+, Sn2+ and Cu2+, the trivalent metal-based (eg. Sb3+ with ns2 outer-shell electronic configuration) hybrid perovskite with the A3M2X9 formula (A = monovalent cations, M = trivalent metal, X = halide) offer intriguing possibilities for engineering ferroic properties. Here, we synthesized 2D ferroelectric hybrid perovskite (TMA)3Sb2Cl9 with measurable in-plane and out-of-plane polarization. Interestingly, (TMA)3Sb2Cl9 can be intercalated with FeCl4 ions to form a ferroelastic and piezoelectric single crystal, (TMA)4-Fe(iii)Cl4-Sb2Cl9. Density functional theory calculations were carried out to investigate the unusual mechanism of ferroelectric-ferroelastic crossover in these crystals.

Influence of Pd(II) Adsorption on High-Temperature Ferroelastic Phase Transition in (2-Amino-2-thiazolinium)PbBr3

“…Through the propagation of actual domain walls, the domain variant C (dark) in the crystal grows at the expense of the domain variant B (bright), while new nucleated domains C are created (Figure 4d,e). 4 These changes represent that strain can be switched by temperature and mechanical stress, which is strong evidence that 1 undergoes a ferroelastic phase transition. In addition, 1-Pd was made into a thin film to observe the change of domains, and it was found that neither the heating and cooling process nor the mechanical stressing process changed significantly, indicating the disappearance of ferroelasticity after adsorption (Figure S6).…”

“…Moreover, by clamping the bulk crystal of 1 with tweezers along the crystallographic axis, the changes in the domain structure can be observed after applying mechanical stress at 300 K: after applying the stress, the domains show similar texture and higher density. Through the propagation of actual domain walls, the domain variant C (dark) in the crystal grows at the expense of the domain variant B (bright), while new nucleated domains C are created (Figure d,e) . These changes represent that strain can be switched by temperature and mechanical stress, which is strong evidence that 1 undergoes a ferroelastic phase transition.…”

“…Ordinary crystals have a linear relationship between the stress and strain within the elastic limit; however, in a certain temperature range, the stress and strain of some crystals do not have a linear relationship but show a complicated relationship similar to the hysteresis loop in ferroelectrics, such crystals are called ferroelastics. − As a major class of materials with ferroic properties, ferroelastic materials have received special attention in the applications of mechanical switches and piezoelectric sensors due to their amazing mechanical and physical properties. At first, ferroelastic materials were found in a few inorganic oxides such as BaTiO 3 and Gd 2 (MoO 4 ) 3 , while ferroelasticity was also found in a number of organic molecular materials. − Recently, increasingly developing fields have put forward more demands on ferroelastic materials, such as low acoustic impedance, light weight, high biocompatibility, and good flexibility.…”

Metal ion induced dual switchable dielectric and luminescent properties in hybrid halides

“…The above analysis of hydrogen bonding forces indicates that the intermolecular forces weaken with increasing temperature, leading to changes in the molecular structure and causing the phase transition behavior. 34,35 As dielectric materials, the dielectric response signal shows a significant abnormality near the phase transition temperature. [36][37][38] The dielectric constant rises sharply as the temperature rises to the phase transition temperature because the phase transition of the crystal structure triggered by the molecular order-disorder change exhibits significant dielectric anomalies near the phase transition temperature.…”

“…The above analysis of hydrogen bonding forces indicates that the intermolecular forces weaken with increasing temperature, leading to changes in the molecular structure and causing the phase transition behavior. 34,35…”