Perovskite-like ABX₃ metal–organic frameworks (MOFs) have gathered great interest due to their intriguing chemical and physical properties, including their magnetism, ferroelectricity, and multiferroicity. Pressure is an effective thermal parameter in tuning related properties in MOFs due to the adjustable organic framework. Though spectrum experiments have been made on the structural evolution during decompression, there is a lack of electrical studies on the order–disorder ferroelectric transition in the metal–organic frameworks under pressure. In this work, we use a static pyroelectric current measurement, a dynamic dielectric method combined with a Raman scattering technique with applying in situ pressure, to explore the order–disorder ferroelectric transition in [(CH₃)₂NH₂]Co(HCOO)₃. The ferroelectric transition vanishes around the external pressure of 1.6 GPa, emerging with a new paraelectric phase. Another phase transition was observed at 6.32 GPa, mainly associated with the distortive transition of DMA⁺ cations. A phenomenological theory of ferroelectricity vanishing at 1.6 GPa for [(CH₃)₂NH₂]Co(HCOO)₃ is also discussed. Our study gives a comprehensive understanding in the pressure tuning of ferroelectric properties in hybrid inorganic–organic materials.

中文翻译：

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氢键金属有机骨架中压力对有序无序铁电跃迁的影响

像钙钛矿一样的ABX ₃金属有机框架（MOF）由于其令人着迷的化学和物理特性（包括磁性，铁电性和多铁性）而引起了极大的兴趣。由于有机骨架可调，压力是调节MOF中相关属性的有效热参数。尽管已经对减压过程中的结构演化进行了光谱实验，但仍缺乏有关压力下金属-有机骨架中有序-无序铁电跃迁的电学研究。在这项工作中，我们使用静态热释电电流测量，动态电介质方法与拉曼散射技术相结合并施加原位压力，来探索[（CH₃）₂ NH ₂ ] Co（HCOO）₃。铁电跃迁在1.6 GPa的外部压力附近消失，并出现新的顺电相。在6.32 GPa处观察到另一个相变，主要与DMA ⁺阳离子的畸变转变有关。还讨论了[（CH ₃）₂ NH ₂ ] Co（HCOO）₃在1.6 GPa消失的铁电现象学理论。我们的研究对杂化无机-有机材料中铁电特性的压力调节提供了全面的了解。