https://doi.org/10.1140/epjb/e2016-70142-3
Regular Article
Discrete breathers in alpha-uranium
1 Institute for Metals Superplasticity Problems, Russian Academy of Sciences, 39 Khalturin Street, 450001 Ufa, Russia
2 School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore, Singapore
3 Ufa State Aviation Technical University, 12 K. Marx Street, 450000 Ufa, Russia
4 NSC Kharkov Institute of Physics and Technology, Akademicheskya Str. 1, 61108 Kharkov, Ukraine
5 Research Laboratory for Mechanics of New Nanomaterials, Peter the Great St.Petersburg Polytechnic University, 195251 St. Petersburg, Russia
a
e-mail: elena.a.korznikova@gmail.com
Received: 6 March 2016
Received in final form: 27 May 2016
Published online: 18 July 2016
Uranium is an important radioactive material used in the field of nuclear energy and it is interesting from the scientific point of view because it possesses unique structure and properties. There exist several experimental reports on anomalies of physical properties of uranium that have not been yet explained. Manley et al. [Phys. Rev. Lett. 96, 125501 (2006); Phys. Rev. B 77, 214305 (2008)] speculate that the excitation of discrete breathers (DBs) could be the reason for anisotropy of thermal expansion and for the deviation of heat capacity from the theoretical prediction in the high temperature range. In the present work, with the use of molecular dynamics, the existence of DBs in α-uranium is demonstrated and their properties are studied. It is found that DB frequency lies above the phonon band and increases with DB amplitude. DB is localized on half a dozen of atoms belonging to a straight atomic chain. DB in uranium, unlike DBs in fcc, bcc and hcp metals, is almost immobile. Thus, the DB reported in this study cannot contribute to thermal conductivity and the search for other types of DBs in α-uranium should be continued. Our results demonstrate that even metals with low-symmetry crystal lattices such as the orthorhombic lattice of α-uranium can support DBs.
Key words: Solid State and Materials
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2016