Electronic Structure and Bonding in YTi2Ga4 – A Gallide with Linear Titanium Chains and Four-bonded Gallium Atoms

Abstract

The gallium-rich ternary intermetallic compound YTi₂Ga₄ is isotypic with YbMo₂Al₄, I4/mmm, Z =2. Yttrium is located in a large cage built up by 12 gallium atoms. Chains of condensed Y@Ga₁₂ polyhedra and linear titanium chains build up a tetragonal rod packing. The gallium atoms are bonded within Ga4 squares (265 pm Ga-Ga) which are condensed via longer Ga-Ga bonds (292 pm) to a three-dimensional gallium substructure with formally four-connected gallium, in agreement with a Bader charge partitioning scheme [YTi₂]⁴⁺[Ga₄]^4-. These features are addressed with electronic structure and chemical bonding considerations. The metallic behavior of YTi₂Ga₄ is found to be of the itinerant electron type within the valence band and Ti d-like states at E_F. Ga-Ga and Ti-Ga bonding characteristics provide mechanical properties derived from the full set of elastic constants leading to a brittle material.

Graphical Abstract

Electronic Structure and Bonding in YTi2Ga4 – A Gallide with Linear Titanium Chains and Four-bonded Gallium Atoms