An Above-Room-Temperature Phase Transition with Dielectric-Switching Properties in a Halogenobismuthate(III) - Tris(Cyclohexylmethylammonium) Pentabromobismuthate(III) Bromide

作者：Yin, Zi; Gao, Ji-Xing; Chen, Hai-Peng; Liao, Wei-Qiang^*

来源：European Journal of Inorganic Chemistry, 2017, 2017(29): 3555-3560.

DOI：10.1002/ejic.201700529

• Phase transitions
• Bismuth
• Dielectric properties
• Structure elucidation

A one-dimensional halogenobismuthate(III), [CMA]3 center dot[BiBr5]center dot[Br] (1, CMA = cyclohexylmethylammonium), is discovered as a high-temperature phase-transition material with reversible and switchable dielectric behavior. Compound 1 undergoes a solid-state phase transition at T-C = 401.6 K, as confirmed by differential scanning calorimetry (DSC), variabletemperature single-crystal X-ray diffraction, variable-temperature powder X-ray diffraction (PXRD), and dielectric measurements. Compound 1 crystalizes in the monoclinic space group P2(1)/c in the room-temperature phase (RTP). The asymmetric unit of 1 consists of three independent CMA cations, one isolated Br- anion, and one [BiBr5](2-) anion, which extends along the c axis to form a one-dimensional zigzag chain through corner-sharing BiBr6 octahedra. Interestingly, the temperature-dependent dielectric constants display striking steplike dielectric anomalies with two distinct dielectric states below and above TC; therefore, 1 could be conceived to be an appealing candidate for dielectric switches. It is believed that this finding might pave the way to the exploration and design of high-temperature phase-transition materials for practical applications.

• 出版日期2017-8-10
• 单位东南大学