中国物理B ›› 2020, Vol. 29 ›› Issue (7): 77801-077801.doi: 10.1088/1674-1056/ab99b4

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

A theoretical study on chemical ordering of 38-atom trimetallic Pd-Ag-Pt nanoalloys

Songül Taran, Ali Kemal Garip, Haydar Arslan   

  1. 1 Department of Physics, Duzce University, Duzce 81620, Turkey;
    2 Department of Physics, Zonguldak Bulent Ecevit University, Zonguldak 67100, Turkey
  • 收稿日期:2020-03-25 修回日期:2020-05-28 出版日期:2020-07-05 发布日期:2020-07-05
  • 通讯作者: Songül Taran E-mail:songultaran@duzce.edu.tr

A theoretical study on chemical ordering of 38-atom trimetallic Pd-Ag-Pt nanoalloys

Songül Taran1, Ali Kemal Garip2, Haydar Arslan2   

  1. 1 Department of Physics, Duzce University, Duzce 81620, Turkey;
    2 Department of Physics, Zonguldak Bulent Ecevit University, Zonguldak 67100, Turkey
  • Received:2020-03-25 Revised:2020-05-28 Online:2020-07-05 Published:2020-07-05
  • Contact: Songül Taran E-mail:songultaran@duzce.edu.tr

摘要: In this study, truncated octahedron (TO) structure is selected for further analysis and we focus on 38-atom Pd-Pt-Ag trimetallic nanoalloys. The best chemical ordering structures of PdnAg32-nPt6 trimetallic nanoalloys are obtained at Gupta level. The structures with the lowest energy at Gupta level are then re-optimized by density functional theory (DFT) relaxations and DFT results confirm the Gupta level calculations with small shifts on bond lengths indicating TO structure is favorable for 38-atom of PdnAg32-nPt6 trimetallic nanoalloys. The DFT excess energy analysis shows that Pd8Ag24Pt6 composition has the lowest excess energy value in common with excess energy analysis at Gupta level. In Pd8Ag24Pt6 composition, eight Pd atoms are central sites of 8 (111) hexagonal facets of TO, 24 Ag atoms locate on surface, and 6 Pt atoms locate at the core of the structure. It is also obtained that all of the compositions except Pd18Ag14Pt6 and Pd20Ag12Pt6 exhibit a octahedral Pt core. Besides, it is observed that there is a clear tendency for Ag atoms to segregate to the surface and also Pt atoms prefer to locate at core due to order parameter (R) variations.

关键词: nanoalloys, chemical ordering, optimization, density functional theory (DFT)

Abstract: In this study, truncated octahedron (TO) structure is selected for further analysis and we focus on 38-atom Pd-Pt-Ag trimetallic nanoalloys. The best chemical ordering structures of PdnAg32-nPt6 trimetallic nanoalloys are obtained at Gupta level. The structures with the lowest energy at Gupta level are then re-optimized by density functional theory (DFT) relaxations and DFT results confirm the Gupta level calculations with small shifts on bond lengths indicating TO structure is favorable for 38-atom of PdnAg32-nPt6 trimetallic nanoalloys. The DFT excess energy analysis shows that Pd8Ag24Pt6 composition has the lowest excess energy value in common with excess energy analysis at Gupta level. In Pd8Ag24Pt6 composition, eight Pd atoms are central sites of 8 (111) hexagonal facets of TO, 24 Ag atoms locate on surface, and 6 Pt atoms locate at the core of the structure. It is also obtained that all of the compositions except Pd18Ag14Pt6 and Pd20Ag12Pt6 exhibit a octahedral Pt core. Besides, it is observed that there is a clear tendency for Ag atoms to segregate to the surface and also Pt atoms prefer to locate at core due to order parameter (R) variations.

Key words: nanoalloys, chemical ordering, optimization, density functional theory (DFT)

中图分类号:  (Nanocrystals, nanoparticles, and nanoclusters)

  • 78.67.Bf
36.40.-c (Atomic and molecular clusters)