Materials Data on Ba4SiAs4 by Materials Project
Ba4SiAs4 crystallizes in the cubic P-43n space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded to six As3- atoms to form BaAs6 octahedra that share corners with six equivalent BaAs6 octahedra, corners with three equivalent SiAs4 tetrahedra, edges with twelve BaAs6 octahedra, and a faceface with one SiAs4 tetrahedra. The corner-sharing octahedra tilt angles range from 17–19°. All Ba–As bond lengths are 3.44 Å. In the second Ba2+ site, Ba2+ is bonded to six As3- atoms to form BaAs6 octahedra that share corners with six BaAs6 octahedra, corners with three SiAs4 tetrahedra, edges with twelve BaAs6 octahedra, and a faceface with one SiAs4 tetrahedra. The corner-sharing octahedra tilt angles range from 17–20°. There are a spread of Ba–As bond distances ranging from 3.40–3.46 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four equivalent As3- atoms to form SiAs4 tetrahedra that share corners with twelve equivalent BaAs6 octahedra and faces with four equivalent BaAs6 octahedra. The corner-sharing octahedral tilt angles are 52°. All Si–As bond lengths are 2.43 Å. In the second Si4+ site, Si4+ is bonded to four equivalent As3- atoms to form SiAs4 tetrahedra that share corners with twelve BaAs6 octahedra and faces with four equivalent BaAs6 octahedra. The corner-sharing octahedra tilt angles range from 48–52°. All Si–As bond lengths are 2.44 Å. There are two inequivalent As3- sites. In the first As3- site, As3- is bonded in a 7-coordinate geometry to six Ba2+ and one Si4+ atom. In the second As3- site, As3- is bonded in a 7-coordinate geometry to six Ba2+ and one Si4+ atom.