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Electronic Structure of K2Bi8Se13

Published online by Cambridge University Press:  21 March 2011

Daniel I Bilc
Affiliation:
Michigan State University, Department of Physics and Astronomy, East Lansing, MI 48824, U.S.A
Paul Larson
Affiliation:
Naval Research Laboratory, Washington D.C., U.S.A
S.D. Mahanti
Affiliation:
Michigan State University, Department of Physics and Astronomy, East Lansing, MI 48824, U.S.A
M.G. Kanatzidis
Affiliation:
Michigan State University, Department of Chemistry, East Lansing, MI 48824, U.S.A
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Abstract

K2Bi8 Se13 belongs to a class of complex Bi-Te-Se systems which show great potential for thermoelectric performance. This compound forms in two distinct phases α-K2Bi8 Se13 (triclinic with space group P-1) and β-K2Bi8 Se13 (monoclinic with space group P 21/m). In the β-phase, there is substantial disorder at four sites in the unit cell, occupied by two K and two Bi atoms. To understand the electronic properties of these two different phases we have carried out band structure calculations within ab initio density functional theory (DFT) using full potential linearized augmented plane wave (LAPW) method. The generalized gradient approximation (GGA) was used to treat the exchange and correlation potential. Spin-orbit interaction (SOI) was incorporated using a second variational procedure. The α. phase is found to be a semiconductor with an indirect band gap of 0.47eV. For the β-phase we have chosen two different ordered structures. The system is a semi-metal for one of the structures whereas for the other, it is a narrow gap semiconductor with a gap of 0.38eV in the absence of SOI, but the gap collapses and the system becomes a semimetal with low density of states at the Fermi energy when SOI is included.

Type
Research Article
Copyright
Copyright © Materials Research Society 2002

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References

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