分子铁电体的对称性破缺与畴工程

项目名称： 分子铁电体的对称性破缺与畴工程

项目编号： No.91622104

项目类型： 重大研究计划

立项/批准年度： 2017

项目学科： 数理科学和化学

项目作者： 任申强

作者单位： 东南大学

项目金额： 80万元

中文摘要： 分子铁电是同时具有铁电性、压电性、非线性光学效应和热释电性等多功能的电介质晶态材料。这些优异性质的产生是由于铁电相变中对称性破缺导致的。空间对称性破缺不仅是导致铁电多功能性产生的直接因素，更是导致铁电畴模式形成的重要原因。理清铁电畴模式形成的规律和铁电畴对外加激励的响应更是理解分子铁电极化反转的基础。本项目以铁电性为研究导向，依托新型分子铁电晶态材料，实现铁电功能材料从宏观晶体块材到（亚）微米及数十纳米晶态薄膜的全物理尺度的可控制备。基于不同物理尺度材料的形态，建立微区和实时的测量技术，实现分子铁电晶态材料中电畴结构的高分辨表征。同时，借助共振增强逆压电响应等新技术，发展原位外加光辐射、电场和磁场等多激励下分子铁电材料的响应行为。通过结构对称性分析和功能基元的复合，实现人工原位调制电畴和纳米电场刻印等新型功能材料表征手段。为分子铁电晶态材料走向集成化应用阶段提供新方法和新材料的支持。

中文关键词： 分子铁电；对称性破缺；铁电畴；压电响应力显微镜；畴壁

英文摘要： Molecule ferroelectric is a multi-functional dielectric crystalline material with both ferroelectricity, piezoelectricity, nonlinear optical effect and pyroelectricity. These excellent properties are due to the symmetry breaking during the ferroelectric phase transition. The spatial symmetry breaking is not only a direct factor leading to the generation of ferroelectric multi-functionality, but also an important reason for the pattern formation of ferroelectric domains. It is also the basis for understanding the polarization reversal of ferroelectrics with clarifying the pattern formation of ferroelectric domains and the response of ferroelectric domains to external excitation. This project takes the ferroelectricity as the research direction, and realizes the controllable preparation of the ferroelectric functional material from macroscopic crystal block to (sub) micron and tens of nanometer crystal thin film based on new molecular ferroelectrics. Based on the morphology of materials at different physical scales, micro - area and real - time measurement techniques are established to realize high - resolution characterization of domain structure in molecular ferroelectrics. At the same time, the response of molecular ferroelectric materials under excitation, such as in situ optical radiation, electric field and magnetic field, is developed by means of new techniques, such as resonant enhancement of inverse piezoelectric response. By means of structural symmetry analysis and functional primitive composition, a novel functional material characterization method of artificial in-situ domain modulation and nanometer electric field imprinting can be realized. To provide new methods and new materials support for the molecular ferroelectric crystalline materials to the integrated application state.

英文关键词： molecular ferroelectric;symmetry breaking;ferroelectric domain;piezoelectric response microscopy;domain wall