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Title: Lattice dynamics and phase diagram of aluminum at high temperatures

The dispersion of phonons in the fcc, hcp, and bcc phases of aluminum is calculated at ultrahigh pressures by the method of small displacements in a supercell. The stability of the phonon subsystem is studied. The thermodynamic characteristics are calculated in the quasi-harmonic approximation, and a phase diagram of aluminum is plotted. As compared to the Debye model, the use of a phonon spectrum calculated in the quasi-harmonic approximation significantly broadens the hcp phase field and strongly shifts the phase boundary between the fcc and bcc phases. The normal isentrope is calculated at megabar pressures. It is shown to intersect the fcc-hcp and hcp-bcc phase boundaries. The sound velocity along the normal isentrope is calculated. It is shown to have a nonmonotonic character.
Authors:
; ; ;  [1] ; ;  [2]
  1. National Research Nuclear University 'MEPhI,', Sarov State Institute of Physics and Technology (Russian Federation)
  2. Russian Federal Nuclear Center-All-Russian Research Institute of Experimental Physics (Russian Federation)
Publication Date:
OSTI Identifier:
22210404
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Experimental and Theoretical Physics; Journal Volume: 117; Journal Issue: 4; Other Information: Copyright (c) 2013 Pleiades Publishing, Inc.; http://www.springer-ny.com; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ALUMINIUM; APPROXIMATIONS; BCC LATTICES; COMPARATIVE EVALUATIONS; FCC LATTICES; HCP LATTICES; PHASE DIAGRAMS; PHONONS; SPECTRA; TEMPERATURE RANGE 0400-1000 K; THERMODYNAMIC PROPERTIES