HR: 1340h
AN: MR43C-1523    [Abstracts]
TI: Elasticity of hcp Metals at High Pressure and Temperature: the Quasi-harmonic Case of Cobalt
AU: * Antonangeli, D
EM: antonangeli3@llnl.gov
AF: Energy and Environment Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, United States
AU: Krisch, M
EM: krisch@esrf.fr
AF: European Synchrotron Radiation Facility, 6 rue Jules Horowitz, Grenoble, 38043, France
AU: Farber, D L
EM: farber2@llnl.gov
AF: Energy and Environment Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, United States
AU: Fiquet, G
EM: guillaume.fiquet@impmc.jussieu.fr
AF: Institut de Minéralogie et de Physique des Milieux Condensés (UMR CNRS 7590) and Institut de Physique du Globe de Paris, 140 rue de Lourmel, Paris, 75015, France
AB: High-resolution inelastic x-ray scattering (IXS) measurements have been carried out on a single crystal of hcp cobalt at simultaneous high pressure and high temperature. Four out of five independent moduli of the elastic tensor have been derived from simultaneous velocity and density determinations. Our experiments indicate that the elasticity of hcp-Co at high pressure and temperature is well described within the frame of the quasi- harmonic approximation, and that anharmonic high-temperature effects on the elastic moduli, sound velocities and elastic anisotropy are minimal at constant density. These new results on hcp-cobalt are particularly interesting in light of the controversial case of iron, where, on one hand, nuclear resonant inelastic x-ray scattering measurements [1] suggest a negative correlation between the aggregate sound velocities and temperature at constant density, in violation of the "Birch law", and, on the other hand, ab initio finite temperature molecular dynamics simulations [2] support the validity of the "Birch law" for a large number of systems, including bcc- and hcp-Fe. Finally, these measurements highlight the current capabilities of the IXS technique for the studies of elasticity and phonon dispersion of materials under extreme thermodynamic conditions. [1] J.F. Lin et al., Science 308, 1892 (2005). [2] L. Vočadlo, Earth Planet. Sci. Lett. 254, 227 (2007).
DE: 3909 Elasticity and anelasticity
DE: 3924 High-pressure behavior
DE: 3954 X-ray, neutron, and electron spectroscopy and diffraction
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting