The composition effect for the thermal properties of Pd_nAg_(42-n)Pt₁₃ ternary nanoalloys: a molecular dynamics study

ABSTRACT

In this study, the classical molecular dynamics simulations in canonical ensemble conditions (NVT) were used to investigate the dynamical properties of trimetallic Pd–Pt–Ag nanoalloy clusters with the interatomic interactions modelled by the Gupta many-body potential. The optimisations for best homotops were performed using the basin-hopping algorithm for 55 atom icosahedral Pd_nAg_(42-n)Pt₁₃ trimetallic clusters. We performed optimisations to search the best chemical ordering of icosahedron structure not allowing any geometric changes. The icosahedron structures which are the best homotops have a core-shell segregation. The obtained icosahedral structures with best homotops were taken as the initial configurations for MD simulations. The temperature ranges were explored which the surface sites of the clusters stay thermally stable. We estimated the melting temperatures of Pd_nAg_(42-n)Pt₁₃ trimetallic clusters using caloric curves and Lindemann parameters. No simple correlation between alloy composition and melting temperatures was determined. The Pd₃₅Ag₇Pt₁₃ composition has the highest melting temperature, however, the Pd₂₁Ag₂₁Pt₁₃ is the most stable composition according to the relative stability investigation. The simulation results showed that the melting of all Pd_nAg_(42-n)Pt₁₃ clusters takes place as a whole without any surface premelting.

KEYWORDS:

• Optimisation
• melting
• palladium
• platinum
• silver

Acknowledgements

DL_POLY_4 is a molecular dynamics simulation package written by I.T. Todorov and W. Smith, and has been obtained from STFC’s Daresbury Laboratory via the website ‘http://www.ccp5.ac.uk/DL_POLY’. The author wishes to thank Dr Haydar Arslan and Professor Riccardo Ferrando for useful discussions about simulation results.

Disclosure statement

No potential conflict of interest was reported by the author.

ORCID

Ali Kemal Garip http://orcid.org/0000-0002-9299-4641

Additional information

Funding

The author also acknowledges the support from Zonguldak Bülent Ecevit University Scientific Research Projects Coordinatorship foundation with the project code 2016-22794455-02.