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Theoretical Calculation of the Vibrational modes in Ge46 Clathrate and Related MxGayGe46-y Type Clathrates

Published online by Cambridge University Press:  10 February 2011

Jianjun Dong ,
Otto F. Sankey ,
A. A. Demkov ,
Ganesh K. Ramachandran ,
Jan Gryko ,
Paul McMillan  and
Wolfgang Windl
Jianjun Dong
Affiliation:
Department of Physics and Astronomy and Materials Research Center, Arizona State University, Tempe, Arizona 85287
Otto F. Sankey
Affiliation:
Department of Physics and Astronomy and Materials Research Center, Arizona State University, Tempe, Arizona 85287
A. A. Demkov
Affiliation:
Motorola Inc., Mesa AZ
Ganesh K. Ramachandran
Affiliation:
Department of Chemistry and Materials Research Center, Arizona State University
Jan Gryko
Affiliation:
Department of Chemistry and Materials Research Center, Arizona State University Jacksonville State University
Paul McMillan
Affiliation:
Department of Chemistry and Materials Research Center, Arizona State University
Wolfgang Windl
Affiliation:
Motorola Inc, Los Alamos National Laboratory, Los Alamos, NM 87545
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Abstract

We have calculated theoretically the vibrational modes of the type-I Ge46 clathrate and some related Zintl phase structures MxGayGe46-y using ab initio density functional theory. The vibrational modes of pure Ge46 (without guest species) are compared to the MxGayGe46-y structures, and it is found that small metal atoms (e.g. Na) have vanishing restoring force in the large cage, while the larger alkali-earth metal Ba has a restoring force constant less than 10% of that of the a framework atom. This makes them ideal “rattler” systems.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 545: Symposium Z – Thermoelectric Materials 1998 - The Next Generation… , 1998 , 443
Copyright
Copyright © Materials Research Society 1999

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References

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