I.S. Zamulin - Post-graduate Student, Katanov Khakass State University, Abakan. E-mail: zamulin_ivan@mail.ru
S.L. Gafner - Dr.Sc. (Phys.-Math.), Professor, Katanov Khakass State University, Abakan. E-mail: sgafner@khsu.ru sgafner@rambler
L.V. Redel - Ph.D. (Phys.-Math.), Associate Professor, Katanov Khakass State University, Abakan. Е-mail: lredel@khsu.ru
Yu.Ya. Gafner - Dr.Sc. (Phys.-Math.), Professor, Head of Department, Katanov Khakass State University, Abakan. Е-mail: ygafner@khsu.ru

We studied the structural transitions in small clusters of some metals from platinum group using molecular dynamics method involving tight-binding potential. As the initial objects we used the spherical FCC clusters of Pt, Pd and Rh with diameter to 2 nm and obtained in the process of cutting out the sphere from the ideal FCC lattice. The article states that some metal nanoclusters have the icosahedral structure though the mentioned chemical elements had the FCC lattice in the macroscopic state. The presence of 5-part symmetry was observed in the clusters of a certain size, but the clusters exceeding this size did not have the icosahedral structure. Besides, using computer modeling we found out that along with ihfcc transition influenced by size effects there may be the inverse fccih transition connected with the thermal action. These results demonstrate existence of some energy barrier between the structural states of cluster which depends on the size of a particle. The studies show that FCC lattice as stable structure predominates in small size nanoclusters of Pt and Pd while icosahedral lattice predominates in Rh. While conducting computer modeling special attention was paid to analyzing the influence of magic numbers on the structural transitions in the process of thermal action in the studied nanoclusters.

 

1. Rubahn H.G. Nanophysik und Nanotechnologie. Teubner. 2004. 184 p.
2. Edelstein A S. Nanomaterials: Synthesis, Properties, and Applications. Bristol: Institute of Physics Publ. 1996. 596 p.
3. Smirnov B. M. Protsessy generatsii klasternykh puchkov // UFN. 2003. T. 173. Vyp. 6. S. 609-648.
4. Pauly H. Atom, Molecule, and Cluster Beams. V. 2. Cluster Beams, Fast and Slow Beams, Accessory Equipment, and Applications. Berlin: Springer. 2000. 376 p.
5. Perez A., Melinon P., Dupuis V., et al. Cluster assembled materials: a novel class of nanostructured solids with original structures and properties // J. Phys. D: Appl. Phys. 1997. V. 30. P. 709-721.
6. Makarov G.N. Ekstremal'nye protsessy v klasterakh pri stolknovenii s tverdoy poverkhnost'yu // UFN. 2006. T. 176. S. 121-174.
7. Panigrahi S., Kundu S., Ghosh S. K., et al. General method of synthesis for metal nanoparticles // Journal of Nanoparticle Research. 2004. № 6. R. 411-414.
8. H. Hofmeister Forty Years Study of Fivefold Twinned Structures in Small Particles and Thin Films // Crystal Research and Technology. 1998. № 33. P. 3-25.
9. Gryaznov V. G., Heydenreich J., Kaprelov A. M., et al. Pentagonal Symmetry and Disclinations in Small Particles // Crystal Research and Technology. 1999. № 34. P. 1091-1119
10. Smirnov B.M. Klastery s plotnoy upakovkoy i zapolnennymi obolochkami // UFN.-1993. T. 163. № 10. S. 29 - 56.
11. Yeletskiy A.V. «Ekzoticheskie» ob''ekty atomnoy fiziki // SOZh. 1999. № 4. S. 86-96.
12. Cleri F., Rosato V. Tight-binding potentials for transition metals and alloys // Phys. Rev. B. 1993. № 48. P. 22 - 33.
13. Gafner S.L., Redel' L.V., Gafner Yu.Ya. K voprosu o formirovanii strukturnykh modifikatsiy v nanoklasterakh Ni // Fizika metallov i metallovedenie. 2007. T. 104. № 2. S. 189-195.
14. Gafner S.L., Redel' L.V., Gafner Yu.Ya. Modelirovanie protsessov strukturoobrazovaniya nanoklasterov medi v ramkakh potentsiala sil'noy svyazi // ZhETF. 2009. T. 135. № 5. S. 899-916.
15. Nose S. A unified formulation of the constant temperature molecular dynamics methods // J. Phys. Chem. 1984. № 81. P. 511-519.
16. Pang T. An introduction to computational physics. Cambridge: University Press. 2006. P. 385.Chang-hong Yao, Bin Song, Pei-lin Cao. Structures of Al_19 cluster: A full-potential LMTO molecular-dynamics study // Phys. Rev. B. 2004. V. 70. № 7. P. 155-160.