Dresden 2003 – wissenschaftliches Programm
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SYEC: Materials under extreme conditions
SYEC 3: Extreme Conditions (Poster Session)
SYEC 3.4: Poster
Mittwoch, 26. März 2003, 13:00–19:00, P2a
Inelastic x-ray scattering in Cs under pressure — •I. Loa1, K. Kunc1,2, K. Syassen1, M. Krisch3, A. Mermet3, and M. Hanfland3 — 1MPI für Festkörperforschung, D-70569 Stuttgart, Germany — 2CNRS and Université Pierre et Marie Curie, F-75252 Paris, France — 3European Synchrotron Radiation Facility, F-38043 Grenoble, France
Recent progress in synchrotron inelastic x-ray scattering (IXS) has made possible the measurement of phonon dispersions throughout the Brillouin zone from 100-µm-size samples pressurized in a diamond anvil cell. Here, we report results of high-pressure IXS experiments on the bcc and fcc phases of Cs. Our study was partly motivated by recent predictions of small or negative mode Grüneisen parameters in fcc-Cs and related anomalies in thermodynamic properties [1–3]. The experimental challenge was that the phonons of interest have quite low frequencies (∼4 meV ≈ 30 cm−1 at ambient). We compare the experimental data obtained for zone-boundary LA phonon frequencies with results of first principles frozen-phonon calculations.
[1] N. E. Christensen et al., J. Phys.: Condens. Matter 12, 3293 (2000).
[2] J. J. Xie et al., Phys. Rev. B 62, 3624 (2000).
[3] Y. Kong and O. Jepsen, J. Phys.: Condens. Matter 12, 8973 (2000).