Vitrification of a monatomic metallic liquid

Bhat, M. Harish; Molinero, Valeria; Soignard, Emmanuel; Solomon, Virgil C.; Sastry, Srikanth; Yarger, Jeffery L.; Angell, C. Austen

doi:10.1038/nature06044

Cited by 207 publications

(151 citation statements)

References 33 publications

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“…However, the latter is more logical and consistent with the LLT behavior of liquid Si and Ge. [2][3]25 The thermodynamically stable crystal 1 has a hexagonal crystal lattice in which each molecule assumes an approximately pyramidal shape. 26 However, a conformational polymorph was found to crystalize in a monoclinic lattice when the process was carried out by fast cooling in an ionic liquid.…”

Section: Fluorescence From C153 Incorporated Into Crystal 1 Of Tpp mentioning

confidence: 99%

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

Mosses

Syme

Wynne

2014

J. Phys. Chem. Lett.

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Liquid-liquid transitions (LLTs) between amorphous phases of a single (chemically unchanged) liquid were predicted to occur in most molecular liquids but have only been observed in triphenyl phosphite (TPP) and n-butanol, and even these examples have been dismissed as "aborted crystallization". One of the foremost reasons that LLTs remain so controversial is the lack of an obvious order parameter, that is, a physical parameter characterizing the phase transition. Here, using the technique of fluorescence lifetime imaging, we show for the first time that the LLT in TPP is characterized by a change in polarity linked to changes in molecular ordering associated with crystal polymorphs. We conclude that the LLT in TPP is a phase transition associated with frustrated molecular clusters, explaining the paucity of examples of LLTs seen in nature.

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Section: Fluorescence From C153 Incorporated Into Crystal 1 Of Tpp mentioning

confidence: 99%

“…2 Amorphous to amorphous LLTs in strongly interacting atomic liquids are well established and have been observed in liquid Ge, Si, P, etc. [3][4][5] as well as melts of Al2O3-Y2O3. 6 It has been predicted 7 that LLTs should be common in all molecular liquids.…”

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confidence: 99%

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

Mosses

Syme

Wynne

2014

J. Phys. Chem. Lett.

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confidence: 99%

Hidden polymorphs drive vitrification in B2O3

Ferlat

Seitsonen²,

Lazzeri³

et al. 2012

Nature Mater

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Understanding the conditions which favor crystallisation or vitrification of liquids has been a long-standing scientific problem [1][2][3]. Another connected, and not yet well understood question is the relationship between the glassy and the various possible crystalline forms a system may adopt [4,5]. In this context, B2O3 is a puzzling case of study since i) it is one of the best glass-forming systems despite an apparent lack of lowpressure polymorphism ii) it vitrifies in a glassy form abnormally different from the only known crystalline phase at ambient pressure [6] iii) it never crystallises from the melt unless pressure is applied, an intriguing behaviour known as the crystallisation anomaly [7][8][9]. Here, by means of ab-initio calculations, we discover the existence of novel B2O3 crystalline polymorphs with structural properties similar to the glass and formation energies comparable to the known ambient crystal. The resulting configurational degeneracy drives the system vitrification at ambient pressure. The degeneracy is lifted under pressure, unveiling the origin of the crystallisation anomaly. This work reconciles the behaviour of B2O3 with that from other glassy systems and reaffirms the role played by polymorphism in a system's ability to vitrify [10,11]. Some of the predicted crystals are cage-like materials entirely made of three-fold rings, opening new perspectives for the synthesis of boron-based nanoporous materials. PACS numbers:Polymorphism, the possibility for a substance to form several distinct crystalline phases of identical composition, is observed for a wide range of materials. This phenomenon has tremendous importance not only per se for understanding the crystallisation process but also because of practical implications such as the design and control of new materials with specific properties [12], a major issue for the pharmaceutical industry [13]. Indeed, the ability of molecular units to pack in various ways generates crystal phases which generally differ in their physical properties and cohesive energies. Another important implication of polymorphism is related to the glassy state: as pointed out earlier [10,11], glass formation is often prevalent for those materials which are found in a variety of crystalline forms. An obvious example is silica (SiO 2 ), the archetypal glass-former, which at low pressure is found as quartz, cristobalite, keatite, tridymite, coesite and moganite [14]. The existence of these many polytypes illustrate that the structural units, here the SiO 4 tetrahedra, can occur in several conformations with little difference in strain energy, allowing for the possibility of metastable states [14]. The ease of glass formation is usually understood as the result of the system frustration associated to the presence of many minima of comparable energy in the crystal energy landscape (CEL). In the context of organic chemistry, it has also been observed that systems with many almost equi-energetic structures containing a common interchangeable motif, correlate with a t...

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“…They have been quite properly called glasses or glassy states. However, there is another category of materials where the amorphous states appear to have some kind of thermodynamic stability with respect to crystallization or melting; particularly interesting among them are pure substances: carbon [32][33][34], semiconductors [35,36], one-component metals [37,38], and water [39]. Such states may be called amorphous phases.…”

Section: Discussionmentioning

confidence: 99%

“…Such states may be called amorphous phases. A number of experimental data indicate that the stability of the amorphous phases in pure substances may be a size effect [32][33][34][35][36][37][38][39].…”

Section: Discussionmentioning

confidence: 99%

Thermodynamic Stability of Transition States in Nanosystems

Umantsev

2009

J Stat Phys

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We present a theory which shows that, in a closed system of fixed volume capable of undergoing a phase transition, the transition state can be thermodynamically stable against the bulk phases if a certain material parameters criterion is fulfilled. In a small system below the critical size the transition state turns into a globally stable phase that can be observed experimentally. This effect is analogous to stabilization of icosahedral structures in clusters of certain sizes and energies. Stabilization of the transition state in small systems of limited resources allows us to conjecture that, in the case of a melting/freezing transition in pure substances, this state corresponds to an amorphous phase. Although unstable in open systems, this phase may be observed experimentally due to slow kinetics of its decomposition at low temperatures. The material-parameters criterion should help experimenters select the materials for the experimental verification of the phenomenon. In the present paper we consider thin films where the phase separation is permitted only parallel to the plane of the film. The calculations, however, hold true for 3D small systems: e.g., nanoparticles.

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Vitrification of a monatomic metallic liquid

Cited by 207 publications

References 33 publications

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

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

Hidden polymorphs drive vitrification in B2O3

Thermodynamic Stability of Transition States in Nanosystems

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