Crystal and electronic structure of La₂LiAlGe₂

Chem. Met. Alloys 5 (2012) 148-154

https://doi.org/10.30970/cma5.0223

Andrij STETSKIV, Ivan TARASIUK, Volodymyr PAVLYUK

The new quaternary dilanthanum lithium aluminum digermanide La₂LiAlGe₂ crystallizes with a structure derivative of the orthorhombic α-GdSi₂, tetragonal α-ThSi₂ and LaPtSi types. The relations between these structures are described by a group-subgroup scheme on the basis of Bärnighausen formalism. The crystal structure consists of six crystallographically distinct atom sites in Wyckoff positions 2a and 2b (space group Imm2), site symmetry mm2. The La atoms are surrounded by 20-vertex Frank-Kasper polyhedra. The germanium, lithium and aluminum atoms are coordinated by tricapped trigonal prisms. The bonding between the atoms was explored by means of the TB-LMTO-ASA (tight-binding linear muffin-tin orbital atomic spheres approximation) method. The highest electron concentration is around Ge. The density of states at the Fermi level indicates metallic behavior.

Projection of the unit cell and coordination polyhedra of the atoms.

Keywords

Intermetallic compound / Crystal structure / Electronic structure / Rare earth elements / Lithium