高岭土-极性客体插层超分子铁电材料的制备及性能研究

Ferroelectric materials with giant dielectric constants have become one focus of condensed matter physics and solid-state electric fields for their important applications in information electric and solid-state devices. Based on the design idea of supramolecular chemistry, the project chooses kaolinite as host materials and a series of designed and synthesized polar molecules with special organic functional groups, such as hydroxyl, carbonyl, amino group and so on, as guest ones to insert into kaolinite layers in order to produce one new kaolinite intercalation supramolecular ferroelectric materials under mild reaction conditions by means of autoclave improved the pressure of system. After kaolinite pretreatment, polar molecules synthesis, optimization of reaction conditions and tests of related thermodynamic performances, a theoretical model for preparation of kaolinite intercalation supramolecular compounds in autoclave will be constructed and their ferroelectric and dielectric property will be researched. The research may provide a novel attacking approach for designation of ferroelectric and giant dielectric materials, and also enrich preparation methods of supramolecular compounds. As a result, it may not only present some key paraments for deeply researching of this method, but also provide the theory basis for researching and developing of other layer mineral materials in field of ferroelectric and giant dielectric materials in the future.

高介电常数的铁电材料在信息电子和固态器件方面有着非常重要的应用，已成为凝聚态物理、固体电子学领域的研究热点。本项目根据超分子化学设计思想，选择天然矿物高岭土作为主体材料，并借助不锈钢高压釜，提升反应体系压力，实现在温和条件下，将设计合成的一系列含羟基、羰基、氨基等基团的极性客体分子插入高岭土层间，制备新的高岭土插层型超分子铁电材料。通过对高岭土的预处理和极性分子的预合成，优化反应条件，测试相关热力学性能，构建不锈钢高压釜法制备高岭土插层型超分子化合物的理论模型，并进行铁电和介电性能研究。本研究为铁电和高介电材料设计提供了新思路，同时丰富了超分子化合物的制备方法。不仅能为不锈钢高压釜法制备高岭土插层型超分子化合物的进一步研究提供关键参数，而且为今后层状矿物材料在铁电和高介电材料领域的开发和利用，提供理论依据。

高岭土具有极性非心层状结构，在外电场作用下，层间极性客体分子可以趋向某种有序排列、或者偶极矩发生反转，因此极性分子-高岭土插层复合物可望被应用在高介电常数的铁电材料中。我们选择广东水洗和安徽产高岭土为主体材料，通过高压釜提升体系压力，制备了三个系列的极性客体分子-高岭土插层复合物，包括1）小分子系列：DMSO/Urea、醋酸盐、甲酰胺/乙酰胺/NMF、乙醇胺、乙二醇、甘氨酸、水合肼；2）六元芳香环 系列：(2,3,4)-氨基吡啶、磺基水杨酸；3）两性离子（内盐）系列：2-吡啶羧酸、2-吡嗪羧酸。并对以上样品的结构、光谱、介电性能开展了一系列研究。研究表明，该方法具有一定的普适性，尤其适合极性小分子插层，部分适用带六元芳香环和两性离子（内盐）结构的极性分子插层，并且所需反应时间能缩短至5-12小时。性能测试证实，高岭土插层复合物是一类介电体，交变电场下可以观察到明显的介电弛豫行为；外电场作用下，片层中水、DMSO、Urea、氨基吡啶 等客体分子，可以实现极性反转呈现铁电性，而醋酸钾、2-吡啶羧酸具有离子导体行为；铁电测量过程中，样品吸潮和电磁信号干扰会对高岭土插层复合物的铁电性能产生影响。进一步功能化高岭土的研究，可以从剥片-组装制备配合物-高岭土超分子复合物着手。