Configurational order-disorder induced metal-nonmetal transition in B13C2 studied with first-principles superatom-special quasirandom structure method

A. Ektarawong, S. I. Simak, L. Hultman, J. Birch, and B. Alling
Phys. Rev. B 92, 014202 – Published 6 July 2015

Abstract

Due to a large discrepancy between theory and experiment, the electronic character of crystalline boron carbide B13C2 has been a controversial topic in the field of icosahedral boron-rich solids. We demonstrate that this discrepancy is removed when configurational disorder is accurately considered in the theoretical calculations. We find that while the ordered ground state B13C2 is metallic, the configurationally disordered B13C2, modeled with a superatom-special quasirandom structure method, goes through a metal to nonmetal transition as the degree of disorder is increased with increasing temperature. Specifically, one of the chain-end carbon atoms in the CBC chains substitutes a neighboring equatorial boron atom in a B12 icosahedron bonded to it, giving rise to a B11Ce(BBC) unit. The atomic configuration of the substitutionally disordered B13C2 thus tends to be dominated by a mixture between B12(CBC) and B11Ce(BBC). Due to splitting of valence states in B11Ce(BBC), the electron deficiency in B12(CBC) is gradually compensated.

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  • Received 2 February 2015
  • Revised 19 May 2015

DOI:https://doi.org/10.1103/PhysRevB.92.014202

©2015 American Physical Society

Authors & Affiliations

A. Ektarawong1,*, S. I. Simak2, L. Hultman1, J. Birch1, and B. Alling1,3

  • 1Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
  • 2Theoretical Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden
  • 3Max-Planck-Institut für Eisenforschung GmbH, D-40237 Düsseldorf, Germany

  • *anekt@ifm.liu.se

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Vol. 92, Iss. 1 — 1 July 2015

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