Calorimetric Study of Frustrated Smectic Liquid Crystals

受阻近晶液晶的量热研究

• 批准号: 8702052
• 负责人: Carl Garland
• 金额: --
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-06-01 至 1990-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8702052&HistoricalAwards=false
• 关键词: Calorimetric; Study; Frustrated; Smectic; Liquid

Professor Garland proposes to carry out high-resolution calorimetric measurements on a variety of polar liquid crystal molecules containing long aromatic cores and on binary mixtures of such molecules. There are two competing order parameters in these systems, and in general they exhibit smectic fluctuations in the nematic phase at two characteristic wavevectors that are incommensurate. Such frustrated compounds can form a wide variety of ordered smectic-A and analogous smectic-C phases. Thus there are many interesting nematic-smecatic transitions and smectic-smectic transitions involving two different smectic-A phases or a smectic-A and a smectic-C phase. An automated, computer-controlled ac microcalorimeter will provide high resolution heat capacity data for second-order phase transitions, special critical and bicritical points, and even weakly first-order transitions. Analysis of such data allows one to characaterize the critical energy fluctuations associated with smectic ordering. The results will test the validity of current theory and should stimulate new and more realistic theoretical models.

加兰教授建议进行高分辨率 各种极性液晶的量热测量 含有长芳香核的分子和二元混合物 这样的分子。 中有两个相互竞争的顺序参数， 这些系统，一般来说，他们表现出近晶波动 在两个特征波矢处的反射相位中， 不相称 这种受挫折的化合物可以形成广泛的 各种有序的近晶-A和类似的近晶-C相。 因此，存在许多有趣的向线-向土转变， 涉及两种不同近晶-A的近晶-近晶转变 相或近晶-A和近晶-C相。 一个自动化的，计算机控制的交流微量热计将 提供二阶相的高分辨率热容数据 过渡，特殊的临界点和双临界点，甚至 弱一阶跃迁 分析这些数据， 来描述与之相关的临界能量波动 近晶有序 其结果将检验当前的有效性 理论，并应激发新的和更现实的理论 模型