A new organic–inorganic ABX₃ perovskite-type semiconducting hybrid, N-methylpyrrolidinium trichlorocadmate (MPCC), has been synthesized. It is found that MPCC exhibits semiconducting behaviour with an optical bandgap of ∼4.65 eV, as well as remarkable dielectric switching properties. It displays a structural phase transition (SPT) at T_c = 254 K, being confirmed by DSC and specific heat measurements. Dielectric measurements display distinct step-like anomalies around T_c, suggesting MPCC as a switchable dielectric material. Variable temperature single-crystal X-ray diffraction reveals that symmetry-breaking occurs from Pnma (at 280 K, >T_c) to P2₁/c (at 230 K, <T_c), which is attributed to the ordering of the disordered N-methylpyrrolidinium (MP) cation. The most distinct difference between its low- and high-temperature structures is the order–disorder dynamics of the MP cation, which mainly contribute to the SPT and switchable dielectric activities of MPCC. This finding paves a new way for designing multi-featured ABX₃-type SPT hybrids by choosing disordered cationic moieties.

中文翻译：

---

[C ₅ H ₁₂ N] CdCl ₃：ABX ₃钙钛矿型半导体可转换介电相变材料

合成了一种新的有机-无机ABX ₃钙钛矿型半导体杂化物，N-甲基吡咯烷鎓三氯cadnate（MPCC）。发现MPCC表现出半导体行为，光学带隙约为4.65 eV，并且具有显着的介电开关特性。它显示了在T _c = 254 K时的结构相变（SPT），这已通过DSC和比热测量得到了证实。介电测量结果显示在T _c附近存在明显的阶梯状异常，这表明MPCC是可切换的介电材料。可变温度单晶X射线衍射表明，对称断裂发生于Pnma（在280 K，> T _c）到P 2 ₁ / c（在230 K，< T _c），这归因于无序的N-甲基吡咯烷鎓（MP）阳离子的有序性。其低温和高温结构之间最明显的区别是MP阳离子的有序无序动力学，这主要有助于MPCC的SPT和可切换的介电活性。该发现为通过选择无序的阳离子部分来设计多功能ABX ₃型SPT杂种铺平了一条新途径。