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A5: Nanoscale and low dimensional effects

Neutron Scattering Investigation of Phonon Scattering Rates in Ag1-xSb1+xTe2+x

J. Ma1, O. Delaire2, E. Specht2, J. Budai2, A. May2, M. McGuire2, Tao. Hong1, O. Gourdon1, D. Abernathy1, and G. Ehlers1
1Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA, 2Material science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA

The phonon dispersions and scattering rates of the thermoelectric material AgSbTe2 were measured as a function of temperature with inelastic neutron scattering. The results show that phonon scattering rates are large and weakly dependent on temperature. The lattice thermal conductivity was calculated from the measured phonon lifetimes and group velocities, providing good agreement with bulk transport measurements. The measured phonon scattering rates and their temperature dependence are compared with models of phonon scattering by anharmonicity and point defect. We find that these processes cannot account for the large total phonon scattering rates observed, and their lack of temperature dependence. Additional neutron diffraction measurements suggest that a nanostructure inherent to the material could be responsible for the strong phonon scattering.