Details

Autor(en) / Beteiligte

• Chakoumakos, B. C
• Keppens, V
• Mandrus, D
• Sales, B. C
• Dai, P
• Coldea, R
• Maple, M. B
• Gajewski, D. A
• Freeman, E. J
• Bennington, S

Titel

Localized vibrational modes in metallic solids

Ist Teil von

• Nature (London), 1998-10, Vol.395 (6705), p.876-878

Ort / Verlag

London: Nature Publishing

Erscheinungsjahr

1998

Quelle

EBSCOhost Psychology and Behavioral Sciences Collection

Beschreibungen/Notizen

• Filled skutterudite antimonides, are cubic compounds with the formula RM4Sb12, where R is a rare-earth element (such as La or Ce), and M is a transition metal (for example, Fe or Co). The rare-earth ion is weakly bound in an oversized atomic cage formed by the other atoms. Its presence has been shown to cause a dramatic reduction in the lattice component of the thermal conductivity, while having little effect on the electronic properties of the compound. This combination of properties makes filled skutterudites of interest as thermoelectric materials. It has been suggested that localized, incoherent vibrations of the rare-earth ion are responsible for the reduction in thermal conductivity, but no direct evidence for these local vibrational modes exists. Here we report the observation of local modes in La-filled skutterudites, using heat capacity, elastic constant and inelastic neutron scattering measurements. The La atoms show unusual thermodynamic behaviour, characterized by the presence of two low-energy localized modes. Our results suggest that consideration of local modes will play an important role in the design of the next generation of thermoelectric materials.