Structural and Electronic Properties of Type I Clathrates M^sub 8^Ga^sub 16^Ge^sub 30^ (M = Ba, Sr, Yb) from First-Principles Calculations

In this work, the effects of filling atoms on the structural and electronic properties of type I clathrates M^sub 8^Ga^sub 16^Ge^sub 30^ (M = Ba, Sr, Yb) have been investigated by first-principles calculations. It is found that these alloys are all indirect-gap semiconductors, among which Yb^sub 8^G...

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Bibliographic Details
Published in:Journal of electronic materials 2011-05, Vol.40 (5), p.1298
Main Authors: Li, D C, Fang, L, Deng, S K, Ruan, H B, Saleem, M, Wei, W H, Kong, C Y
Format: Article
Language:English
Subjects:
Alloys
Atoms & subatomic particles
Density
Heat conductivity
Semiconductors
Online Access:Get full text
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Summary:In this work, the effects of filling atoms on the structural and electronic properties of type I clathrates M^sub 8^Ga^sub 16^Ge^sub 30^ (M = Ba, Sr, Yb) have been investigated by first-principles calculations. It is found that these alloys are all indirect-gap semiconductors, among which Yb^sub 8^Ga^sub 16^Ge^sub 30^ possesses the smallest band gap and the largest bulk modulus, and a unique feature of a sharp peak in the density of states (DOS) near the Fermi level, implying good potential as a thermoelectric material for band engineering. Moreover, calculations indicate direct chemical bonds between Yb and the nearest host Ga/Ge atoms, which can play an important role in the reduction of the lattice thermal conductivity via large off-center rattling of the Yb in the larger cage of the clathrate structure, suggesting that Yb^sub 8^Ga^sub 16^Ge^sub 30^ is of interest for future thermoelectric applications. [PUBLICATION ABSTRACT]
ISSN:0361-5235
1543-186X