scholarly journals Polyamorphism Mirrors Polymorphism in the Liquid–Liquid Transition of a Molecular Liquid

2020 ◽  
Vol 142 (16) ◽  
pp. 7591-7597 ◽  
Author(s):  
Finlay Walton ◽  
John Bolling ◽  
Andrew Farrell ◽  
Jamie MacEwen ◽  
Christopher D. Syme ◽  
...  
Keyword(s):  
Molecular Liquid ◽  
Liquid Transition

scholarly journals Microscopic identification of the order parameter governing liquid–liquid transition in a molecular liquid

2015 ◽  
Vol 112 (19) ◽  
pp. 5956-5961 ◽  
Author(s):  
Ken-ichiro Murata ◽  
Hajime Tanaka
Keyword(s):  
Order Parameter ◽  
Structural Evolution ◽  
Characteristic Size ◽  
Number Density ◽  
Time Resolved ◽  
X Ray ◽  
Molecular Liquid ◽  
X Ray Scattering ◽  
Liquid Transition ◽  
Scattering Measurements

A liquid–liquid transition (LLT) in a single-component substance is an unconventional phase transition from one liquid to another. LLT has recently attracted considerable attention because of its fundamental importance in our understanding of the liquid state. To access the order parameter governing LLT from a microscopic viewpoint, here we follow the structural evolution during the LLT of an organic molecular liquid, triphenyl phosphite (TPP), by time-resolved small- and wide-angle X-ray scattering measurements. We find that locally favored clusters, whose characteristic size is a few nanometers, are spontaneously formed and their number density monotonically increases during LLT. This strongly suggests that the order parameter of LLT is the number density of locally favored structures and of nonconserved nature. We also show that the locally favored structures are distinct from the crystal structure and these two types of orderings compete with each other. Thus, our study not only experimentally identifies the structural order parameter governing LLT, but also may settle a long-standing debate on the nature of the transition in TPP, i.e., whether the transition is LLT or merely microcrystal formation.

scholarly journals Order Parameter of the Liquid–Liquid Transition in a Molecular Liquid

2014 ◽  
Vol 6 (1) ◽  
pp. 38-43 ◽  
Author(s):  
Joanna Mosses ◽  
Christopher D. Syme ◽  
Klaas Wynne
Keyword(s):  
Order Parameter ◽  
Molecular Liquid ◽  
Liquid Transition

scholarly journals Link between molecular mobility and order parameter during liquid–liquid transition of a molecular liquid

2019 ◽  
Vol 116 (15) ◽  
pp. 7176-7185 ◽  
Author(s):  
Ken-ichiro Murata ◽  
Hajime Tanaka
Keyword(s):  
Molecular Dynamics ◽  
Molecular Mobility ◽  
Order Parameter ◽  
Temporal Change ◽  
Glassy State ◽  
Unstable State ◽  
Local Order ◽  
Time Resolved ◽  
Molecular Liquid ◽  
Liquid Transition

Liquid–liquid transition (LLT) is the transformation of one liquid to another via first-order phase transition. For example, LLT in a molecular liquid, triphenyl phosphite, is macroscopically the transformation from liquid I in a supercooled state to liquid II in a glassy state. Reflecting the transformation from the liquid to glassy state, the LLT is accompanied by considerable slowing down of overall molecular dynamics, but little is known about how this proceeds at a molecular level coupled with the evolution of the order parameter. We report such information by performing time-resolved simultaneous measurements of dielectric spectroscopy and phase contrast microscopy/Raman spectroscopy by using a dielectric cell with transparent electrodes. We find that the temporal change in molecular mobility crucially depends on whether LLT is nucleation growth type occurring in the metastable state or SD type occurring in the unstable state. Furthermore, our results suggest that the molecular mobility is controlled by the local order parameter: more specifically, the local activation energy of molecular rotation is controlled by the local fraction of locally favored structures formed in the liquid. Our study sheds light on the temporal change in the molecular dynamics during LLT and its link to the order parameter evolution.

scholarly journals Drastic enhancement of crystal nucleation in a molecular liquid by its liquid–liquid transition

2019 ◽  
Vol 116 (50) ◽  
pp. 24949-24955 ◽  
Author(s):  
Rei Kurita ◽  
Hajime Tanaka
Keyword(s):  
Phase Transition ◽  
Order Parameter ◽  
Experimental Studies ◽  
Grain Structure ◽  
Crystal Nucleation ◽  
Control Factor ◽  
Mechanical And Thermal Properties ◽  
Molecular Liquid ◽  
Nucleation Frequency ◽  
Liquid Transition

Crystallization is one of the most familiar and fundamental phase transition phenomena. There is a possibility that crystallization may be enhanced by critical-like fluctuations associated with another nearby phase transition if the order parameter of the former is coupled to that of the latter; however, the mechanism of such order parameter coupling and its generality remain elusive due to the lack of experimental studies. Here we report experimental evidence for a nontrivial coupling between crystallization and liquid–liquid transition (LLT) for a molecular liquid, triphenyl phosphite. We find that the crystal nucleation frequency is drastically enhanced by short-time preannealing near but above the spinodal temperature of LLT. By successfully separating the thermodynamic and kinetic factors governing crystal nucleation, we show that this enhancement is induced by the lowering of the crystal–liquid interfacial energy due to the presence of critical-like order parameter fluctuations. This finding may be regarded as a fingerprint of the presence of LLT below the melting point. Thus, it may allow us not only to control the crystal nucleation frequency by LLT but also to unveil LLT hidden behind crystallization. This enhancement of nucleation frequency by critical-like fluctuations of another ordering phenomenon may be general to a variety of combinations of phase transitions. It would provide a way to control a crystal grain structure, which is a crucial control factor of mechanical and thermal properties of crystalline materials.

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