TITLE:
Metal Hexaborides with Sc, Ti or Mn
AUTHORS:
Ian D. R. Mackinnon, Jose A. Alarco, Peter C. Talbot
KEYWORDS:
Metal Hexaborides; Electronic Structure; Superconductivity; Boron Framework
JOURNAL NAME:
Modeling and Numerical Simulation of Material Science,
Vol.3 No.4,
October
15,
2013
ABSTRACT:
Comparison of well-determined single crystal data for
stoichiometric, or near-stoichiometric, metal hexaborides confirms previously identified lattice parameter trends using powder diffraction. Trends
for both divalent and trivalent forms suggest that potential new forms for
synthesis include Sc and Mn hexaborides. Density Functional Theory (DFT)
calculations for KB6, CaB6, YB6, LaB6,
boron octahedral clusters and Sc and Mn forms show that the shapes of bonding
orbitals are defined by the boron framework. Inclusion of metal into the boron
framework induces a reduction in energy ranging from 1 eV to 6 eV increasing
with ionic charge. For metals with d1 character, such a shift in
energy brings a doubly degenerate band section along with the G-M
reciprocal space direction within the conduction bands tangential to the Fermi
surface. ScB6 band structure and density of states calculations show
directions and gap characteristics similar to those of YB6 and LaB6.
These calculations for ScB6 suggest that it may be
possible to realize superconductivity in this compound if synthesized.