DOE OSTI2020
Ba3(LiAs)4 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Li1+ is bonded to four As+2.50- atoms to form LiAs4 tetrahedra that share a cornercorner with one BaAs6 octahedra, corners with ten equivalent LiAs4 tetrahedra, edges with two equivalent BaAs6 octahedra, and edges with three equivalent LiAs4 tetrahedra. The corner-sharing octahedral tilt angles are 52°. There are three shorter (2.82 Å) and one longer (2.97 Å) Li–As bond lengths. There are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 6-coordinate geometry to six As+2.50- atoms. There are four shorter (3.40 Å) and two longer (3.42 Å) Ba–As bond lengths. In the second Ba2+ site, Ba2+ is bonded to six As+2.50- atoms to form BaAs6 octahedra that share corners with four equivalent LiAs4 tetrahedra, edges with two equivalent BaAs6 octahedra, and edges with eight equivalent LiAs4 tetrahedra. There are four shorter (3.35 Å) and two longer (3.37 Å) Ba–As bond lengths. There are two inequivalent As+2.50- sites. In the first As+2.50- site, As+2.50- is bonded in a 9-coordinate geometry to two equivalent Li1+, six Ba2+, and one As+2.50- atom. The As–As bond length is 2.52 Å. In the second As+2.50- site, As+2.50- is bonded in a 6-coordinate geometry to six equivalent Li1+ and three Ba2+ atoms.