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SYEC: Materials under extreme conditions

SYEC 1: Extreme Conditions I

SYEC 1.3: Hauptvortrag

Mittwoch, 26. März 2003, 15:00–15:30, HSZ/01

High-pressure studies of lattice dynamics by nuclear inelastic scattering of synchrotron radiation — •Gerhard Wortmann — Department of Physics, University of Paderborn, D-33095 Paderborn, Germany

Recent high-pressure experiments with resonant nuclear inelastic scattering (NIS) of synchrotron radiation (SR) are shortly reviewed [1, 2]. Then we present NIS studies of the ε-phase of iron, where, using the pressure induced texture of the sample, the phonon DOS was derived as seen parallel and perpendicular to the hexagonal c-axis of ε-Fe [3, 4]. Recent pressure- and temperature-dependent Fe-57 NIS studies of Fe₆₅Ni₃₅, the “classical” Invar system, provide detailed information about specific properties of the local phonon-DOS and their relationship with the Invar properties. Suppression of the Invar properties is observed around 12 GPa by a loss in magnetism [4] and by discontinuities in the pressure dependence of the derived elastic parameters [4]. Finally we present Sn-119 NIS studies of SnO [5] where again the pressure-induced texture was used to derive the local phonon-DOS as seen parallel and perpendicular to the tetragonal c-axis.

[1] R. Lübbers, H.F. Grünsteudel, A.I. Chumakov, G. Wortmann, Science 287, 1250 (2000).

[2] H.-K. Mao et al., Science 292, 914 (2001).

[3] H. Giefers et al., High Pressure Research 22, 501 (2002).

[4, 5] K. Rupprecht et al.; H. Giefers et al.; contrib. to this symposium. Work supported by the BMBF (05-KS1PPB/3).