We have performed density functional calculations of the vibrational modes of three tin-based, cagelike clathrate materials: the pure type-I (Sn46) and type-II (Sn136) frameworks, and the donor/acceptor compensated compound Cs8Ga8Sn38: We have also theoretically identified the infrared- and Raman-active modes in these materials and have computed their Raman spectra. In addition, we report measurements of the Raman spectrum of Cs8Ga8Sn38 and compare the experimental spectrum with the theoretical one. By this means, we are able to unambiguously identify the low-frequency "rattling" vibrational modes in this material, which are due to the motion of the Cs atoms that are loosely bound in the Sn cages.
|Number of pages||21168730|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Jun 15 2002|