Beryllium-Based ABX₃-Type Organic–Inorganic Hybrid Halide Ferroelastic

Organic-inorganic hybrid ferroelastic materials attract great interest in multiple application scenarios, including data storage, shape memory, actuators, mechanical switches, etc. Despite hybrid molecular ferroelastics being the subject of extensive studies due to their remarkable structural and compositional versatility, hybrid metal halide ferroelastics composed of group IIA metal elements have rarely been reported up to now. Herein, a beryllium (Be)-based hybrid halide ABX₃-type ferroelastic, CBA-BeF₃ (CBA = cyclobutylamine), has been reported for the first time. CBA-BeF₃ demonstrates an order-disorder structural phase transition at 356 K, accompanied by a distinct change in symmetry that belongs to the paraelastic-ferroelastic transition with an Aizu notation of <i>mmmF</i>2/<i>m</i>. The observation of ferroelastic domain evolution and stress-strain hysteresis phenomena indicates the ferroelastic nature of CBA-BeF₃. This work showcases a brand-new family of hybrid halide ferroelastics and is of great inspiration to explore more group IIA metal-based ferroelastic materials.