Intercalation-driven ferroelectric-to-ferroelastic conversion in a layered hybrid perovskite crystal
Zhenyue Wu, Shunning Li, Yasmin Mohamed Yousry, Walter P. D. Wong, Xinyun Wang, Teng Ma, Zhefeng Chen, Yan Shao, Weng Heng Liew, Kui Yao, Feng Pan, Kian Ping Loh
Abstract
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 Pb 2+ , Sn 2+ and Cu 2+ , the trivalent metal-based (eg. Sb 3+ with ns2 outer-shell electronic configuration) hybrid perovskite with the A 3 M 2 X 9 formula (A = monovalent cations, M = trivalent metal, X = halide) offer intriguing possibilities for engineering ferroic properties. Here, we synthesized 2D ferroelectric hybrid perovskite (TMA) 3 Sb 2 Cl 9 with measurable in-plane and out-of-plane polarization. Interestingly, (TMA) 3 Sb 2 Cl 9 can be intercalated with FeCl 4 ions to form a ferroelastic and piezoelectric single crystal, (TMA) 4 -Fe(iii)Cl 4 -Sb 2 Cl 9 . Density functional theory calculations were carried out to investigate the unusual mechanism of ferroelectric-ferroelastic crossover in these crystals.