Structural characterization, thermal, dielectric, vibrational properties and molecular motions in
作者:A. Piecha、R. Jakubas、A. Pietraszko、J. Baran、W. Medycki、D. Kruk
DOI:10.1016/j.jssc.2009.08.007
日期:2009.11
characterized by the X-ray (at 293 and 110 K), calorimetric, dilatometric and dielectric measurements. At room temperature it crystallizes in the monoclinic space group, C2/m . A crystal structure consists of disordered imidazolium cations and ordered discrete tetramers of [Bi4Br18]6-[Bi4Br18]6-. This compound reveals a rich polymorphism in a solid state. It undergoes three solid–solid phase transitions:
合成了[C 3 N 2 H 5 ] 6 [Bi 4 Br 18 ] [C3N2H5] 6 [Bi4Br18],并通过X射线(293和110 K),量热,膨胀和介电测量对其进行了表征。在室温下,它在单斜晶空间群C 2 / m中 结晶。晶体结构由无序的咪唑鎓阳离子和[Bi 4 Br 18 ] 6- [ Bi 4 Br 18 ] 6-的有序离散四聚体组成。该化合物显示出丰富的固态多态性。它经历了三个固-固相变:在426/423 K下从I相到II相(加热-冷却),II→IIIII→III在227 K和III→IVIII→IV在219.5 / 219 K时。室温II相中发现了清晰的介电弛豫过程。多晶[C 3 N 2 H 5 ] 6 [Bi 4 Br 18 ] [C3N2H5] 6 [Bi4Br18]的红外研究表明,ν(N–H)ν(N–H),δδ (环)和δ(咪唑鎓阳离子的C–H)δ(C–H)模式似