Inelastic scattering on antimony bearing thermoelectric materials: rattlers revisited

Antimony element specific measurements on EuFe$_4$Sb$_{12}$ and Zn$_4$Sb$_3$ will be presented in parallel with inelastic neutron scattering measurements on Zn$_4$Sb$_3$. These results yield new insight in the rattler concept. First, the antimony specific DOS in EuFe$_4$Sb$_{12}$ and CoSb$_{3}$ provides experimental insight into the guest-host interaction mechanism which is required for a lowering of the thermal conductivity[1]. Second, the scattering vector dependence of the Zn$_4$Sb$_3$ inelastic response reveals that ''rattling'' behavior is not restricted to single atoms and that more complex structural units, such as dumbbells, can exhibit a similar behavior that is responsible for a low thermal conductivity.[2] [The European Synchrotron Radiation Facility is acknowledged for provision of the synchrotron radiation facility at beamlines ID18 and ID22N and the European Community - ARI HPRI-2001-00175 is acknowledged for provision of neutron scattering beam time at the FRJ-II research reactor in J\"ulich, Germany.] [1] Schweika W. et al. Phys. Rev. Lett. 99, 125501 (2007). [2] Wille H.-C. et al. Phys. Rev. B 76, 140301(R) (2007).