Liao Wei-Qiang, Ye Heng-Yun, Zhang Yi, Xiong Ren-Gen
Ordered Matter Science Research Center, Southeast University, Nanjing 211189, PR China.
Dalton Trans. 2015 Jun 21;44(23):10614-20. doi: 10.1039/c4dt02875a. Epub 2014 Nov 20.
A new organic-inorganic hexagonal perovskite-type compound with the formula ABX3, thiazolium tribromocadmate(ii) (1), in which thiazolium cations are situated in the space between the one-dimensional chains of face-sharing CdBr(6) octahedra, has been successfully synthesized. Systematic characterizations including differential scanning calorimetry measurements, variable-temperature structural analyses, and dielectric measurements reveal that it undergoes two structural phase transitions, at 180 and 146 K. These phase transitions are accompanied by remarkable dielectric relaxation and anisotropy. The thiazolium cations remain orientationally disordered during the two phase transition processes. The origins of the phase transitions at 180 and 146 K are ascribed to the slowing down and reorientation of the molecular motions of the cations, respectively. Moreover, the dielectric relaxation process well described by the Cole-Cole equation and the prominent dielectric anisotropy are also connected with the dynamics of the dipolar thiazolium cations.
一种新的分子式为ABX₃的有机-无机六角钙钛矿型化合物，噻唑鎓三溴化镉（II）（1）已成功合成，其中噻唑鎓阳离子位于共面的CdBr₆八面体的一维链之间的空间中。包括差示扫描量热法测量、变温结构分析和介电测量在内的系统表征表明，它在180K和146K经历了两个结构相变。这些相变伴随着显著的介电弛豫和各向异性。在两个相变过程中，噻唑鎓阳离子保持取向无序。180K和146K处相变的起源分别归因于阳离子分子运动的减慢和重新取向。此外，由科尔-科尔方程很好描述的介电弛豫过程和显著的介电各向异性也与偶极噻唑鎓阳离子的动力学有关。
