Covalent bonding and the nature of band gaps in some half-Heusler compounds
By Hem Chandra Kandpal, Claudia Felser, R. Seshadri. 2005
250 citations recorded by the source corpus.
Half-Heusler compounds XYZ, also called semi-Heusler compounds, crystallize in the C1b MgAgAs structure, in the space group . We report a systematic examination of band gaps and the nature (covalent or ionic) of bonding in semiconducting 8- and 18-electron half-Heusler compounds through first-principles density functional calculations. We find that the most appropriate description of these compounds from the viewpoint of electronic structures is one of a YZ zinc blende lattice stuffed by the X ion. Simple valence rules are obeyed for bonding in the 8-electron compound. For example, LiMgN can be written Li+ + (MgN)− and (MgN)−, which is isoelectronic with (SiSi), forms a zinc blende lattice. The 18-electron compounds can similarly be considered as obeying valence rules. A semiconductor such as TiCoSb can be written Ti4+ + (CoSb)4−; the latter unit is isoelectronic and isostructural with zinc-blende GaSb. For both the 8- and the 18-electron compounds, when X is fixed as some electropositive cation, the computed band gap varies approximately as the difference in Pauling electronegativities of Y and Z. What is particularly exciting is that this simple idea of a covalently bonded YZ lattice can also be extended to the very important magnetic half-Heusler phases; we describe these as valence compounds, i.e. possessing a band gap at the Fermi energy albeit only in one spin direction. The local moment in these magnetic compounds resides on the X site.
Subfields: Electronic, Optical and Magnetic Materials, Materials Chemistry
View Paper: https://www.semanticscholar.org/paper/69eef46b6f03398e7af66eec640c7d13eb779d54
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In Electronic, Optical and Magnetic Materials
In Materials Chemistry
- Claudia Felser
- Ashvin Vishwanath
- Xiao-Liang Qi
- Shoucheng Zhang
- N. P. Armitage
- E. Mele
- S. Chadov
- G. Fecher
Citations in the corpus
- Strong phonon softening and avoided crossing in aliovalence-doped heavy-band thermoelectrics (2023, background): “TO splitting in ZrNiSn has been reported 5 and this confirms the existence of polar chemical bonds in HH compounds 30 , associated with the optical phonon scattering in electrical transport.”
- Weyl and Dirac semimetals in three-dimensional solids (2017, background): “In the LiYZ compounds, the calculated gap size is larger for compounds with a large Pauli electronegativity difference of the Y and Z species (Kandpal et al., 2006).”
- Tunable multifunctional topological insulators in ternary Heusler compounds. (2010, background): “and XYZ Heuslers (C1 b ) with 18 valence electron”