稀土-冠醚包合物的分子组装、相变行为及铁介电性质

项目名称： 稀土-冠醚包合物的分子组装、相变行为及铁介电性质

项目编号： No.21471070

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 唐云志

作者单位： 江西理工大学

项目金额： 85万元

中文摘要： 分子基介铁电材料由于其种类多、性能广、可控性强等特点，正成为新一轮介铁电材料的研究热点。离子型稀土具有独特的电子构型，半径大，电荷高，易极化；而冠醚具有可控孔腔，易与客体分子通过配位键、氢键等作用力形成柔性包合物。以两者组装的主客体包合物极有可能发生结构相变，有望获得新型分子基铁介电材料。本研究利用不同类型的冠醚与稀土离子组装，通过反应条件控制，设计合成具有转子-定子型结构、钙钛矿型结构和带插层结构的包合物；通过热分析方法(DSC)测试包合物内部发生的结构变化，获取关于相变机制的信息；通过SHG效应判断铁电相空间群的正确性；通过介电性质测量来研究目标化合物的介电常数随温度和频率变化的依赖性，研究其在不同温度下的介电响应情况；探讨离子型稀土包合物即主客体分子的运动特性及结构相变与介电和铁电性的关系，为新一类高自发极化率、高介电常数、高相变温度铁电体的寻找提供一些新的思路。

中文关键词： 冠醚包合物；稀土离子；相变；铁介电性质

英文摘要： The research on molecular ferroelectric and dielectric material is becoming a new hotspot because of their diversity, wide performance, and easy controllability. Since ionic rare earth elements possess unique electronic configuration of large radius, high charges and easy polarization; crown ether has controllable pore space, can form flexible clathrates with guest molecules via forces of coordination、hydrogen-bonding etc. The host-guest clathrate compounds which assembled from ionic rare earth elements and crown ethers are expected to get a new type of ferro-dielectric materials for their possibility of occurring structural phase transition. This research design and synthesis clathrate compounds of rotor-stator type, perovskite type, and intercalated structures by using different types of crown ethers assemble with rare earth ions under controlled conditions; measure inner structural changes of the clathrates by using DSC (differential scanning calorimetry) measurement to attain information about phase transformation mechanism; judge the validity of space group for target products on ferroelectric phase by SHG (second harmonic generation) effect test; research the temperature-dependence and frequency-dependence properties of dielectric constant for target compounds through dielectric constant measurement, study the dielectric response under different temperature; investigate the kinetic characteristics of ionic rare earth clathrates (host-gust molecules), and the relationship between structural phase transition and ferro-dielectric properties, provide some new ideas for the seek of new-type ferroelectrics with high spontaneous polarization value, high dielectric constant, and high phase transition temperature.

英文关键词： Crown Etherclathrate;Lanthanide ions;phase transition;ferro-dielectric properties