Electronic structure of alkali-pnictide compounds

M. Tegze, J. Hafner

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31 Citations (Scopus)

Abstract

The authors present an investigation of the electronic structure and the crystal binding in a number of metallic and semiconducting alkali-pnictide compounds based on self-consistent linear-muffin-tin-orbital (LMTO) calculations. They show that at all compositions the electronic structure is dominated by the strong attractive potential of the pnictide anions. In compounds with the 'octet' composition A3B (A=alkali metal, B=Bi, Sb) they find a narrow gap separating the highest occupied anion band from the lowest empty cation band. The large difference in valence leads to a very large negative excess volume and a high electronic pressure on the alkali sites. This large electronic pressure leads to a lowering of the (n-1)d states relative to the ns states, especially for the heavy alkalis. As a consequence, the ionic gap in the octet compounds is very narrow and varies in a non-monotonic way in the series (Li, Na, K, Rb, Cs)3-(Sb, Bi). At the equiatomic composition, the alkali-Sb compounds contain infinite spiral Sb chains stabilized by strong (pp sigma ) interactions. The bands close to the Fermi level are formed by bonding, non-bonding, and antibonding Sb p states, with the Fermi level falling into the gap between the non-bonding and the antibonding band. The Bi-rich alkali-Bi compounds are metallic, but the electronic density of states still bears the signature of the strong Bi potential.

Original languageEnglish
Article number011
Pages (from-to)2449-2474
Number of pages26
JournalJournal of Physics: Condensed Matter
Volume4
Issue number10
DOIs
Publication statusPublished - Dec 1 1992

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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