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Metals 2014, 4(3), 359-387; doi:10.3390/met4030359
Article

Crystallization of Supercooled Liquid Elements Induced by Superclusters Containing Magic Atom Numbers

Received: 30 April 2014; in revised form: 10 July 2014 / Accepted: 16 July 2014 / Published: 6 August 2014
(This article belongs to the Special Issue Liquid Metals)
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Abstract: A few experiments have detected icosahedral superclusters in undercooled liquids. These superclusters survive above the crystal melting temperature Tm because all their surface atoms have the same fusion heat as their core atoms, and are melted by liquid homogeneous and heterogeneous nucleation in their core, depending on superheating time and temperature. They act as heterogeneous growth nuclei of crystallized phase at a temperature Tc of the undercooled melt. They contribute to the critical barrier reduction, which becomes smaller than that of crystals containing the same atom number n. After strong superheating, the undercooling rate is still limited because the nucleation of 13-atom superclusters always reduces this barrier, and increases Tc above a homogeneous nucleation temperature equal to Tm/3 in liquid elements. After weak superheating, the most stable superclusters containing n = 13, 55, 147, 309 and 561 atoms survive or melt and determine Tc during undercooling, depending on n and sample volume. The experimental nucleation temperatures Tc of 32 liquid elements and the supercluster melting temperatures are predicted with sample volumes varying by 18 orders of magnitude. The classical Gibbs free energy change is used, adding an enthalpy saving related to the Laplace pressure change associated with supercluster formation, which is quantified for n = 13 and 55.
Keywords: thermal properties; solid-liquid interface energy; crystal nucleation; undercooling; superclusters; liquid-solid transition; overheating; non-metal to metal transition in cluster; Laplace pressure thermal properties; solid-liquid interface energy; crystal nucleation; undercooling; superclusters; liquid-solid transition; overheating; non-metal to metal transition in cluster; Laplace pressure
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Tournier, R.F. Crystallization of Supercooled Liquid Elements Induced by Superclusters Containing Magic Atom Numbers. Metals 2014, 4, 359-387.

AMA Style

Tournier RF. Crystallization of Supercooled Liquid Elements Induced by Superclusters Containing Magic Atom Numbers. Metals. 2014; 4(3):359-387.

Chicago/Turabian Style

Tournier, Robert F. 2014. "Crystallization of Supercooled Liquid Elements Induced by Superclusters Containing Magic Atom Numbers." Metals 4, no. 3: 359-387.


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