We performed small-angle X-ray scattering measurements of liquid Te using a synchrotron radiation facility and observed the maximum scattering intensity near 620 K in the supercooled region (melting temperature 723 K). This result is an experimental observation of the ridge line of the critical density fluctuation associated with the liquid-liquid phase transition that is argued to exist in the supercooled region and verifies the existence of the transition. Similar results have been reported for supercooled liquid water, demonstrating the universality of the liquid-liquid transition concept (or inhomogeneous model) in explaining the thermodynamics of these "anomalous liquids". Moreover, as a more essential issue, it has been demonstrated that liquids can be inhomogeneous at mesoscopic scales, even in their thermal equilibrium state. This will contribute to a greater understanding of the physics of liquids, including glass-forming liquids.
Thermal interface fluctuations of liquids and viscoelastic materials
从液体/空气，粘弹性材料/空气，液体/液体，液体/粘弹性材料界面的广泛的界面的热波动的光谱，测量超过100 Hz至10 MHz的频率范围。得到的光谱进行了比较与波动理论的接口，并发现大多是在相当好的协议，当理论推广到适用于液体/粘弹性材料界面的热波动。使用结合光反射、通过平均相关性的统计降噪和共聚焦显微镜的系统测量光谱。它只需要很小的界面面积（$\sim1\,μ$ m $^2$），相对较短的测量时间（$\lesssim$几分钟），也可以应用于高粘度材料。
The phase behavior of liquids confined in a slit geometry does not reveal a crossover from a three to a two-dimensional behavior as the gap size decreases. Indeed, the prototypical two-dimensional hexatic phase only occurs in liquids confined to a monolayer. Here, we demonstrate that the dimensionality crossover is apparent in the lateral size dependence of the relaxation dynamics of confined liquids, developing a Debye model for the density of vibrational states of confined systems and performing extensive numerical simulations. In confined systems, Mermin-Wagner fluctuations enhance the ampl…
We report a new experimental approach for observing mesoscopic fluctuations underlying the thermodynamic anomalies of ambient liquid water. In this approach, two sound velocity measurements with different frequencies, namely inelastic X-ray scattering (IXS) in THz band and ultrasonic (US) in MHz band, are required to investigate the relaxation phenomenon with the characteristic frequency between the two aforementioned frequencies. We performed IXS measurements to obtain the IXS sound velocity of liquid water from the ambient conditions to the supercritical region of liquid-gas phase transition…
We construct the hydrodynamic theory of coherent collective motion ("flocking") at a solid-liquid interface. The polar order parameter and concentration of a collection of "active" (self-propelled) particles at a planar interface between a passive, isotropic bulk fluid and a solid surface are dynamically coupled to the bulk fluid. We find that such systems are stable, and have long-range orientational order, over a wide range of parameters. When stable, these systems exhibit "giant number fluctuations", i.e., large fluctuations of the number of active particles in a fixed large area. Specifica…
We suggest a simple model to describe polyamorphism in single-component fluids using a maximum-valence approach. The model contains three types of interactions: i) atoms attract each other by van der Waals forces that generate a liquid-gas transition at low pressures, ii) atoms may form covalent bonds that induce association, and iii) bonded atoms attract or repel each other stronger than non-bonded atoms, thus generating liquid-liquid separation. As an example, we qualitatively compare this model with the behavior of liquid sulfur and show that condition (iii) generates a liquid-liquid phase …
The recent discovery of nematic liquid crystals with polar order (ferroelectric nematic) has created immense interest. Despite intensive research, several physical properties of this liquid crystal are yet to be investigated and understood. Here, we report experimental studies on the birefringence and exoelectric coefficient of a polar nematic (NF) liquid crystal. Our experiments directly reveal that the splay fluctuations influence the birefringence several degrees above the nonpolar (N) to polar-nematic (NF) phase transition temperature and the heat capacity exponent obtained from the tilt a…
We compute partial structure factors, Kirkwood-Buff integrals (KBIs) and chemical potentials of model supercooled liquids with and without attractive interactions. We aim at investigating whether relatively small differences in the tail of the radial distribution functions result in contrasting thermodynamic properties. Our results suggest that the attractive potential favours the nucleation of long-range structures. Indeed, upon decreasing temperature, Bathia-Thornton structure factors display anomalous behaviour in the $k\to 0$ limit. KBIs extrapolated to the thermodynamic limit confirm this…
Solidity of viscous liquids. IV. Density fluctuations
本文是探索高粘性液体的固体性的物理后果的系列文章中的第四篇。有人认为，两个基本特征的流事件（两个能量极小值之间的跳跃在配置空间）的局部密度变化和所有粒子位移的总和。在此基础上，提出密度涨落可用含时的Ginzburg-Landau方程描述，方程在k空间中的速率形式为$Γ_0+Dk^2$ with $D\ggΓ_0a^2$，其中$a$是平均分子间距离.该不等式表达了长波长的动力学优势，这意味着哈密顿量（自由能）可以被认为是超本地的。作为理论的一个例子，最简单的非平凡的哈密顿量的情况下，解决了高斯近似的二阶，其中它预测的非对称频率依赖性的等温体积模量与德拜行为在低频率和$ω^{-1/2}$衰减的损失在高频率。最后，一般形式主义的粘性液体动力学的描述，它补充了密度动力学，包括应力场，势能场，和分子取向场，提出。
Recently, maximal valence model has been proposed to model liquid-liquid phase transition induced by polymerization in sulfur. In this paper we present a simple generic model to describe liquid polyamorphism in single-component fluids using a maximum-valence approach for any arbitrary coordination number. The model contains three types of interactions: i) atoms attract each other by van der Waals forces that generate a liquid-gas transition at low pressures, ii) atoms may form covalent bonds that induce association, and iii) additional repulsive forces between atoms with maximal valence and at…
