Journal Article

PreJuSER-11953

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Lattice dynamics of rhenium trioxide from the quasiharmonic approximation

Wdowik, U. D. ; Parlinski, K. ; Chatterji, T.FZJ* ; Rols, S. ; Schober, H.

2010
APS College Park, Md.

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Please use a persistent id in citations: http://hdl.handle.net/2128/10967  doi:10.1103/PhysRevB.82.104301

Abstract: The quasiharmonic theory is applied to study the lattice dynamics and thermal properties of rhenium trioxide, a material exhibiting the negative thermal-expansion phenomenon. Phonons are calculated at several external pressures. The pressure dependence of the M, R, and zone-center phonon modes is analyzed. Relying on the Gruneisen formalism an influence of temperature on the M phonon mode is investigated. The calculated free energy of the system provides predictions for the temperature dependence of such quantities as equilibrium volume and crystal thermal expansivity. The mean-squared vibrations of rhenium-trioxide atoms are investigated versus temperature and pressure. Results of the calculations indicate a softening of the M and R phonons with pressure and a large negative Gruneisen constants for these modes. A decrease in the crystal volume is observed up to 170 K. The thermal-expansion coefficient shows a minimum in the vicinity of 100 K which corresponds to a minimum of the anisotropy in the oxygen thermal vibrations perpendicular to the Re-O bond and along the bond. Anisotropy in the oxygen Debye-Waller factors follows from the anisotropy of the force constants at the oxygen site. Inelastic neutron-scattering measurements performed at room temperature are reported together with the generalized phonon densities of states. A comparison between present calculations and the experimental data as well as other theoretical studies is provided.

Keyword(s): J

Note: Interdisciplinary Modeling Center ICM, Warsaw University, Poland is acknowledged for providing the computer facilities to support part of the present calculations under Grant No. G28-12.

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Contributing Institute(s):

1. Neutronenstreuung (IFF-5)
2. Streumethoden (IFF-4)
3. JCNS (Jülich Centre for Neutron Science JCNS (JCNS) ; JCNS)

Research Program(s):

1. BioSoft: Makromolekulare Systeme und biologische Informationsverarbeitung (P45)
2. Großgeräte für die Forschung mit Photonen, Neutronen und Ionen (PNI) (P55)

Appears in the scientific report 2010

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