各向同性相向列液晶的绝热体积模量和声速

IF 1.5 4区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY
Carlindo Vitoriano
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引用次数: 0

摘要

我们从向列相动力学中得到了向列相液晶各向同性相声速\(\varvec{v}_{\varvec{s}}\)的表达式,该表达式包含了向列-各向同性跃迁的阶参量\(\varvec{Q}_{\varvec{\alpha \beta }}\varvec{(} \textbf{r}\varvec{)}\)与局部质量密度\(\varvec{\rho }\varvec{(} \textbf{r}\varvec{)}\)的不均匀性之间的能量耦合。它不同于众所周知的公式\(\varvec{v}_{\varvec{s}}\varvec{=}\sqrt{\varvec{B}_{\varvec{s}}\varvec{/}\varvec{\rho }_{\varvec{0}}}\),其中\(\varvec{B}_{\varvec{s}}\)是绝热体积模量,\(\varvec{\rho }_{\varvec{0}}\)是\(\varvec{\rho }\varvec{(} \textbf{r}\varvec{)}\)的平均值。利用\(\varvec{v}_{\varvec{s}}\)在低频状态下的测量值,我们计算出\(\varvec{B}_{\varvec{s}}\)作为三种不同液晶温度的函数。出现的临界形式\(\varvec{B}_{\varvec{s}}\)是意想不到的,并且它的物理解释讨论了安德森-格拉尼森参数。给出了向列-各向同性跃迁附近\(\varvec{v}_{\varvec{s}}\)临界倾角的解释。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Adiabatic Bulk Modulus and Sound Velocity of Nematic Liquid Crystals in the Isotropic Phase

We obtain an expression for the sound velocity \(\varvec{v}_{\varvec{s}}\) in the isotropic phase of nematic liquid crystals from the nematodynamics that incorporates the energetic coupling between \(\varvec{Q}_{\varvec{\alpha \beta }}\varvec{(} \textbf{r}\varvec{)}\) (the order parameter of the nematic-isotropic transition) and inhomogeneities in the local mass density \(\varvec{\rho }\varvec{(} \textbf{r}\varvec{)}\). It differs from the well-known formula \(\varvec{v}_{\varvec{s}}\varvec{=}\sqrt{\varvec{B}_{\varvec{s}}\varvec{/}\varvec{\rho }_{\varvec{0}}}\), in which \(\varvec{B}_{\varvec{s}}\) is the adiabatic bulk modulus and \(\varvec{\rho }_{\varvec{0}}\) is the average value of \(\varvec{\rho }\varvec{(} \textbf{r}\varvec{)}\). Using the measured values of \(\varvec{v}_{\varvec{s}}\) in the regime of low frequencies, we then calculate \(\varvec{B}_{\varvec{s}}\) as a function of temperature for three different liquid crystals. The critical form of \(\varvec{B}_{\varvec{s}}\) that emerges is unexpected, and its physical interpretation is discussed in terms of the Anderson-Grüneisen parameter. An explanation for the critical dip of \(\varvec{v}_{\varvec{s}}\) near the nematic-isotropic transition is provided.

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来源期刊
Brazilian Journal of Physics
Brazilian Journal of Physics 物理-物理:综合
CiteScore
2.50
自引率
6.20%
发文量
189
审稿时长
6.0 months
期刊介绍: The Brazilian Journal of Physics is a peer-reviewed international journal published by the Brazilian Physical Society (SBF). The journal publishes new and original research results from all areas of physics, obtained in Brazil and from anywhere else in the world. Contents include theoretical, practical and experimental papers as well as high-quality review papers. Submissions should follow the generally accepted structure for journal articles with basic elements: title, abstract, introduction, results, conclusions, and references.
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