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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Ba4GeAs4 by Materials Project

Ba4GeAs4 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 GeAs4 tetrahedra, edges with twelve BaAs6 octahedra, and a faceface with one GeAs4 tetrahedra. The corner-sharing octahedra tilt angles range from 15–16°. There are three shorter (3.43 Å) and three longer (3.47 Å) Ba–As bond lengths. 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 GeAs4 tetrahedra, edges with twelve BaAs6 octahedra, and a faceface with one GeAs4 tetrahedra. The corner-sharing octahedra tilt angles range from 15–18°. There are a spread of Ba–As bond distances ranging from 3.39–3.48 Å. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four equivalent As3- atoms to form GeAs4 tetrahedra that share corners with twelve equivalent BaAs6 octahedra and faces with four equivalent BaAs6 octahedra. The corner-sharing octahedral tilt angles are 53°. All Ge–As bond lengths are 2.51 Å. In the second Ge4+ site, Ge4+ is bonded to four equivalent As3- atoms to form GeAs4 tetrahedra that share corners with twelve BaAs6 octahedra and faces with four equivalent BaAs6 octahedra. The corner-sharing octahedra tilt angles range from 49–52°. All Ge–As bond lengths are 2.52 Å. There are two inequivalent As3- sites. In the first As3- site, As3- is bonded to six Ba2+ and one Ge4+ atom to form a mixture of distorted edge, face, and corner-sharing AsBa6Ge pentagonal bipyramids. In the second As3- site, As3- is bonded to six Ba2+ and one Ge4+ atom to form a mixture of distorted edge, face, and corner-sharing AsBa6Ge pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(GeAs)2 by Materials Project

Ba(GeAs)2 crystallizes in the tetragonal P4_2mc space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a body-centered cubic geometry to eight equivalent As3- atoms. There are four shorter (3.54 Å) and four longer (3.61 Å) Ba–As bond lengths. In the second Ba2+ site, Ba2+ is bonded in a body-centered cubic geometry to eight equivalent As3- atoms. There are four shorter (3.42 Å) and four longer (3.49 Å) Ba–As bond lengths. There are two inequivalent Ge2+ sites. In the first Ge2+ site, Ge2+ is bonded in a water-like geometry to two equivalent As3- atoms. Both Ge–As bond lengths are 2.46 Å. In the second Ge2+ site, Ge2+ is bonded in a bent 120 degrees geometry to two equivalent As3- atoms. Both Ge–As bond lengths are 2.46 Å. As3- is bonded in a 6-coordinate geometry to four Ba2+ and two Ge2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba2GeAs2 by Materials Project

Ba2GeAs2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 6-coordinate geometry to six As3- atoms. There are a spread of Ba–As bond distances ranging from 3.29–3.72 Å. In the second Ba2+ site, Ba2+ is bonded to six As3- atoms to form edge-sharing BaAs6 octahedra. There are a spread of Ba–As bond distances ranging from 3.33–3.53 Å. Ge2+ is bonded in a bent 120 degrees geometry to two As3- atoms. There are one shorter (2.43 Å) and one longer (2.44 Å) Ge–As bond lengths. There are two inequivalent As3- sites. In the first As3- site, As3- is bonded to six Ba2+ and one Ge2+ atom to form a mixture of distorted corner and edge-sharing AsBa6Ge pentagonal bipyramids. In the second As3- site, As3- is bonded in a 7-coordinate geometry to six Ba2+ and one Ge2+ atom.

36 MATERIALS SCIENCE↗