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DY: Dynamik und Statistische Physik

DY 36: Nonlinear dynamics II

DY 36.6: Vortrag

Mittwoch, 26. März 2003, 17:45–18:00, G\"OR/226

Einstein oscillator in Thallium filled Antimony skutterudites: Inelastic neutron scattering and heat capacity measurements — •Raphaël P. Hermann¹, Werner Schweika², R. Jin³, Fernande Grandjean¹, David Mandrus³, Brian C. Sales³, and Gary J. Long⁴ — ¹Department of Physics, University of Liege, Belgium — ²Institut für Festkörperforschung, Forschungszentrum Jülich — ³Solid State Division, Oak Ridge National Laboratory, U.S.A. — ⁴Department of Chemistry, University of Missouri-Rolla, U.S.A.

Inelastic neutron scattering measurements on several Tl filled skutterudites show a well-defined peak in the vibrational density of states. The peak energy for Tl_0.5Co_3.5Fe_0.5Sb₁₂, Tl_0.8Co₃FeSb₁₂, and Tl_0.8Co₄Sb₁₁Sn is 5.0, 4.9, and 4.7 ± 0.1 meV, respectively. This peak is absent in the unfilled CoSb₃ skutterudite. Comparison of the heat capacity measurements on Tl_0.8Co₄Sb₁₁Sn and CoSb₃ clearly indicates a nearly localized vibrational mode associated with the No-dqrattlingNo-dq thallium atoms in this filled skutterudite compound. The inelastic neutron scattering and heat capacity measurements are both well described by a localized Einstein mode with an Einstein temperature, Θ_E, of 57 ± 2 K. These experimental data provide one of the clearest examples of a local mode behavior in a concentrated metallic system. Further, the inelastic neutron scattering measurements show that substituting antimony by tin in the first near neighbor shell of the thallium atoms broadens the peak in the vibrational density of states.