The AuCu Phase Diagram at the Nano Scale: A Molecular Dynamics Approach

While phase diagrams for metal nanoalloys are important to know the conditions at which a nanoparticle keeps a particular shape and kind of surface, experiments to build phase diagrams at the nanoscale are difficult to implement; a posible alternative is the use of atomistic simulations. In this wor...

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Bibliographic Details
Published inJournal of cluster science Vol. 33; no. 2; pp. 785 - 793
Main Authors Martínez-Muñoz, Henor Ramsés, Mejía-Rosales, Sergio
Format Journal Article
LanguageEnglish
Published New York Springer US 01.03.2022
Springer Nature B.V
Subjects
Alloys
Atoms & subatomic particles
Catalysis
Chemistry
Chemistry and Materials Science
Equilibrium
Geometry
Inorganic Chemistry
Interaction models
Intermetallic compounds
Melting points
Metals
Molecular dynamics
Nanoalloys
Nanochemistry
Nanoparticles
Nucleation
Original Paper
Oxidation
Phase diagrams
Physical Chemistry
Simulation
Temperature
Molecular dynamics
Gold
Melting
Copper
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Summary:While phase diagrams for metal nanoalloys are important to know the conditions at which a nanoparticle keeps a particular shape and kind of surface, experiments to build phase diagrams at the nanoscale are difficult to implement; a posible alternative is the use of atomistic simulations. In this work, a set of molecular dynamics simulations is implemented to build the phase diagram of icosahedral, cuboctahedral, and decahedral AuCu nanoparticles of 2 to 4 nm in size, with several relative concentrations of the metals, using the quantum-corrected version of the Sutton and Chen interaction model. In the obtained phase diagrams, the congruent melting point shifts towards high concentrations of copper in accordance with previous theoretical results, and the local density mapping and bond-order analysis as function of temperature show that for the largest particles, partial premelting of the surface coexists with a pseudo-crystalline region that shrinks as the temperature is incremented, followed by the nucleation of a melted region in the inner volume of the particle that grows until the particle melts as a whole. After melting, it is found that gold has a tendency to migrate to the surface, but the alloy remains in the whole volume of the nanoparticle.
ISSN:1040-7278
1572-8862
DOI:10.1007/s10876-021-02015-6