Synthesis and Mechanistic Studies of New Series of Ferroelastic and Ferroelectric Crystals

新型铁弹铁电晶体系列的合成及机理研究

• 批准号: 0809845
• 负责人: Mark Hollingsworth
• 金额: $ 39万
• 依托单位: Kansas State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0809845&HistoricalAwards=false
• 关键词: Synthesis; Mechanistic; Studies; New; Series

One of the principal goals of modern crystal engineering is the design, synthesis and optimization of new materials with specified function. This research program focuses on the technologically useful properties of ferroelastic and ferroelectric domain switching, in which theorientations of domains or regions within a crystal can be changed by application of anisotropic stress (ferroelasticity) or electric fields (ferroelectricity). The rational design of such materials (which can act as light gates or memory devices) requires a deeper understanding of the mechanisms of domain switching, a visible, macroscopic phenomenon that is controlled at the molecular, nanoscopic and mesoscopic scales. Building upon earlier work on the molecular determinants of ferroelasticity, this work will focus on mechanistic studies of domain switching in series of ferroelastic andferroelectric crystals in which the cooperative, elastic barriers to domain switching and ferroelectric ordering can be optimized and tailored. Because such a large number of closely related structures can be generated and compared, it concentrates on the design, synthesis and mechanistic studies ofseries of inclusion compounds, co-crystals and organic salts that exhibit ferroelastic and/or ferroelectric domain switching.Because of the insights they can provide about the barriers to domain switching, this work will utilize a variety of techniques (e.g., X-ray diffraction, synchrotron white beam X-ray topography, solid state nuclear magnetic resonance, ultrafast videomicroscopy, birefringence mapping) to probethe phenomenon of "memory effects" or "rubber-like behavior," in which the daughter domain that is generated by stress (or electric field) spontaneously reverts back to the parent orientation. A more thorough understanding of such memory effects will facilitate a targeted and iterative approach toforming series of ferroelectric crystals with well-defined properties.Broader Impacts: Because they will be required to integrate results from various methods and to utilize these results in the design of new materials, this research program will provide a broad-based training for undergraduate, graduate and postdoctoral students who will pursue careers in materialschemistry. By integrating numerous experimental results on a series of closely related structures,it should be possible to develop a more fundamental understanding of the factors controlling domain switching and memory effects in a variety of ferroelectric materials. This work will be disseminatedwidely in papers and presentations and utilized in graduate-level courses and undergraduate laboratories.

现代晶体工程的主要目标之一是设计、合成和优化具有特定功能的新材料。该研究计划重点关注铁弹性和铁电域切换的技术上有用的特性，其中晶体内域或区域的方向可以通过施加各向异性应力（铁弹性）或电场（铁电性）来改变。此类材料（可用作光门或存储器件）的合理设计需要更深入地了解域切换机制，域切换是一种在分子、纳米级和介观尺度上控制的可见宏观现象。基于早期关于铁弹性的分子决定因素的工作，这项工作将重点关注一系列铁弹性和铁电晶体中域切换的机制研究，其中可以优化和定制域切换和铁电排序的协作弹性障碍。由于可以生成和比较如此大量的密切相关的结构，因此它专注于表现出铁弹性和/或铁电域转换的一系列包合物、共晶和有机盐的设计、合成和机理研究。他们可以提供有关域转换的障碍，这项工作将利用多种技术（例如，X射线衍射、同步加速器白束X射线形貌、固态核磁共振、超快视频显微镜、双折射测绘）来探测“记忆效应”或“类橡胶行为”的现象，其中由压力（或电场）产生的子域自发地恢复到母体方向。对这种记忆效应的更彻底的了解将有助于采用有针对性的迭代方法来形成一系列具有明确特性的铁电晶体。更广泛的影响：因为他们将需要整合各种方法的结果，并在新的设计中利用这些结果材料，该研究计划将为从事材料化学职业的本科生、研究生和博士后提供广泛的培训。通过整合一系列密切相关结构的大量实验结果，应该可以对各种铁电材料中控制磁畴切换和记忆效应的因素有更基本的了解。这项工作将在论文和演示文稿中广泛传播，并在研究生课程和本科生实验室中使用。