厘米级无铅卤化物双钙钛矿单晶实现铁弹性相变触发介电开关性质

Centimeter-sized single crystal of a lead-free halide double perovskite with ferroelastic phase transition-triggered switchable dielectric properties

在铅基卤化物钙钛矿突破性发展的推动下,卤化物双钙钛矿因其环境友好、丰富的物理化学性能和结构可调性而成为杰出的多用途材料.尽管卤化物双钙钛矿的研究取得了飞速的进展,但在这个吸引人的钙钛矿家族中对可切换电介质的探索仍然很少.本工作通过溶液冷却法成功地生长了单层卤化物双钙钛矿(3-溴丙胺)_(4)AgBiBr_(8)(1)的大尺寸单晶,其尺寸达20 mm×17 mm×5 mm.它经历了由Aizu符号定义的mmm F2/m的铁弹性相变,通过结构分析可知该铁弹相变是八面体畸变和柔性分子运动协同作用的结果.值得注意的是,它在373 K附近具有理想的铁弹性相变触发的可切换电介质性能,可以在两个稳定的电介质状态之间切换.而且,1展现出间接带隙半导体特性和X射线响应,其中在40 V的偏压下1的灵敏度高达517μC Gy_(air)^(-1)cm^(-2).这项工作为具有智能功能的无铅卤化物双钙钛矿提供了一条有效的应用路径.

Driven by the breakthrough development of lead(Pb)-based halide perovskites,halide double perovskites have also emerged as remarkably multipurpose materials owing to their environmental friendliness,abundant physicochemical properties,and structural tunability.However,despite their recent soaring progress,the realization of switchable dielectrics in this fascinating family remains considerably less explored.In this study,centimeter-sized single crystals of a single-layer halide double perovskite(3-bromopropylaminium)_(4)AgBiBr_(8)(1)with dimensions up to 20 mm×17 mm×5 mm have been successfully synthesized by using the solution cooling method.The single crystal undergoes a ferroelastic phase transition of mmmF2/m defined by the Aizu notation,which is attributed to the synergistic interaction between octahedral distortion and flexible molecular motion according to structural analysis.Noteworthily,it possesses desirable ferroelastic phase transition-triggered switchable dielectric properties near the high temperature of 373 K,which can be switched between two stable dielectric states.Additionally,1 possesses an indirect-bandgap semiconducting feature and exhibits an X-ray response with a sensitivity of up to 517μC Gy_(air)^(-1) cm^(-2) at a 40 V bias voltage.We believe that this study provides another efficient application path for Pb-free halide double perovskites with intelligent functions.