We report the physicochemical characteristics of a novel Sb-based formamidinium ferroelectric material, (NH₂CHNH₂)₃Sb₂I₉ (FAIA). FAIA crystallizes at room temperature in the hexagonal P6₃mc space group. The crystal structure of FAIA is isomorphic to that of its bismuth analog, [NH₂CHNH₂]₃Bi₂I₉ (FAIB), which is characterized by a zero dimensional (0D) anionic network (discrete bioctahedral units). From the DSC results three phase transitions (PT) have been found for FAIA: at 187.4/189 K (phase I ↔ phase II), 177.6/177.9 K (II ↔ III) and 148.2/152.3 K (III ↔ IV). The compound exhibits ferroelectricity in the room temperature phase I and in the successive temperature phases (II and III). The spontaneous polarization (P_S = 0.5 × 10⁻² μC cm⁻²) reversibility has been confirmed by the presence of the ferroelectric hysteresis loops and pyroelectric measurements. The origin of ferroelectricity is discussed in terms of the cationic dynamics. This material may be considered as a semiconductor (σ ∼ 10⁻⁶ S m⁻¹, 300 K).

中文翻译：

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[NH2CHNH2] 3Sb2I9：基于锑（III）作为潜在半导体吸收剂的无铅，低毒的有机-无机混合铁电体

我们报告了一种新型的基于Sb的甲ami铁电材料（NH ₂ CHNH ₂）₃ Sb ₂ I ₉（FAIA）的理化特性。FAIA在室温下在六边形P 6 ₃ mc空间群中结晶。FAIA的晶体结构与其铋类似物[NH ₂ CHNH ₂ ] ₃ Bi ₂ I ₉（FAIB）的同构，其特征在于零维（0D）阴离子网络（离散的生物体单元）。从DSC结果三相转变（PT）已发现为FAIA：在187.4 / 189 K（相我↔阶段II），177.6 / 177.9 K（II ↔ III）和148.2 / 152.3 K（III ↔ IV）。该化合物在室温阶段I和随后的温度阶段（II和III）中显示出铁电性。自发极化（P_小号= 0.5×10 ^-2 μC厘米^-2铁电磁滞回线和热电测量结果证实了可逆性。根据阳离子动力学讨论铁电的起源。该材料可以被认为是半导体（σ〜10 ^-6 S M ^-1，300K）。