Can undoped calcium tetraborides exist? An answer from the comparison of its density functional theory electronic structure with that of rare-earth metal tetraboride.

Abstract

Periodic density functional theory calculations are used to discuss the existence of metal tetraborides MB4 with divalent metals. Tetraborides which contain metal atoms inserted in a three-dimensional boron network made of B6 octahedra and B2 dumbbells exhibit a pseudo energy gap for a count of 60 valence electrons per M4(B6)2(B2)2 formula unit. Such a count satisfies the stability electron requirement for B6(2-) (20 electrons) octahedra and B2(2-) (8 electrons) units and allows the filling of two supplementary low-lying bands deriving from the valence metallic d atomic orbitals. This favored electron count is not reached for CaB4 which is then formally deficient by one electron per metal atom. This indicates that CaB4 is unlikely to exist without n-doping.

DOI: 10.1021/ic701967n

Cite this paper

@article{Yahia2008CanUC, title={Can undoped calcium tetraborides exist? An answer from the comparison of its density functional theory electronic structure with that of rare-earth metal tetraboride.}, author={Mouna Ben Yahia and Olaf Reckeweg and R{\'e}gis Gautier and Joseph M. Bauer and Thomas Schleid and Jean-François Halet and Jean-Yves Saillard}, journal={Inorganic chemistry}, year={2008}, volume={47 14}, pages={6137-43} }