DOE OSTI2020
Ta2V4Al3C3 is H-Phase-derived structured and crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. there are four inequivalent Ta sites. In the first Ta site, Ta is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All Ta–Al bond lengths are 2.84 Å. All Ta–C bond lengths are 2.16 Å. In the second Ta site, Ta is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All Ta–Al bond lengths are 2.89 Å. All Ta–C bond lengths are 2.18 Å. In the third Ta site, Ta is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All Ta–Al bond lengths are 2.88 Å. All Ta–C bond lengths are 2.17 Å. In the fourth Ta site, Ta is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All Ta–Al bond lengths are 2.84 Å. All Ta–C bond lengths are 2.16 Å. There are eight inequivalent V sites. In the first V site, V is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All V–Al bond lengths are 2.78 Å. All V–C bond lengths are 2.04 Å. In the second V site, V is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All V–Al bond lengths are 2.78 Å. All V–C bond lengths are 2.04 Å. In the third V site, V is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All V–Al bond lengths are 2.72 Å. All V–C bond lengths are 2.04 Å. In the fourth V site, V is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All V–Al bond lengths are 2.77 Å. All V–C bond lengths are 2.05 Å. In the fifth V site, V is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All V–Al bond lengths are 2.78 Å. All V–C bond lengths are 2.04 Å. In the sixth V site, V is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All V–Al bond lengths are 2.72 Å. All V–C bond lengths are 2.04 Å. In the seventh V site, V is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All V–Al bond lengths are 2.75 Å. All V–C bond lengths are 2.04 Å. In the eighth V site, V is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All V–Al bond lengths are 2.74 Å. All V–C bond lengths are 2.04 Å. There are six inequivalent Al sites. In the first Al site, Al is bonded to three equivalent Ta, three equivalent V, and six equivalent Al atoms to form distorted AlTa3Al6V3 cuboctahedra that share corners with six equivalent AlTa3Al6V3 cuboctahedra, corners with six CTa6 octahedra, edges with six equivalent AlTa3Al6V3 cuboctahedra, edges with six CTa6 octahedra, and faces with six equivalent AlTa3Al6V3 cuboctahedra. The corner-sharing octahedra tilt angles range from 16–19°. All Al–Al bond lengths are 2.99 Å. In the second Al site, Al is bonded to six V and six equivalent Al atoms to form AlAl6V6 cuboctahedra that share corners with six equivalent AlAl6V6 cuboctahedra, corners with six CTa3V3 octahedra, edges with six equivalent AlAl6V6 cuboctahedra, edges with six CTa3V3 octahedra, and faces with six equivalent AlAl6V6 cuboctahedra. The corner-sharing octahedra tilt angles range from 19–20°. All Al–Al bond lengths are 2.99 Å. In the third Al site, Al is bonded to six V and six equivalent Al atoms to form AlAl6V6 cuboctahedra that share corners with six equivalent AlAl6V6 cuboctahedra, corners with six CTa3V3 octahedra, edges with six equivalent AlAl6V6 cuboctahedra, edges with six CTa3V3 octahedra, and faces with six equivalent AlAl6V6 cuboctahedra. The corner-sharing octahedra tilt angles range from 19–20°. All Al–Al bond lengths are 2.99 Å. In the fourth Al site, Al is bonded to three equivalent Ta, three equivalent V, and six equivalent Al atoms to form distorted AlTa3Al6V3 cuboctahedra that share corners with six equivalent AlTa3Al6V3 cuboctahedra, corners with six CTa6 octahedra, edges with six equivalent AlTa3Al6V3 cuboctahedra, edges with six CTa6 octahedra, and faces with six equivalent AlTa3Al6V3 cuboctahedra. The corner-sharing octahedra tilt angles range from 16–18°. All Al–Al bond lengths are 2.99 Å. In the fifth Al site, Al is bonded to three equivalent Ta, three equivalent V, and six equivalent Al atoms to form AlTa3Al6V3 cuboctahedra that share corners with six equivalent AlTa3Al6V3 cuboctahedra, corners with six CTa3V3 octahedra, edges with six equivalent AlTa3Al6V3 cuboctahedra, edges with six CTa3V3 octahedra, and faces with six equivalent AlTa3Al6V3 cuboctahedra. The corner-sharing octahedra tilt angles range from 16–19°. All Al–Al bond lengths are 2.99 Å. In the sixth Al site, Al is bonded to three equivalent Ta, three equivalent V, and six equivalent Al atoms to form distorted AlTa3Al6V3 cuboctahedra that share corners with six equivalent AlTa3Al6V3 cuboctahedra, corners with six CTa3V3 octahedra, edges with six equivalent AlTa3Al6V3 cuboctahedra, edges with six CTa3V3 octahedra, and faces with six equivalent AlTa3Al6V3 cuboctahedra. The corner-sharing octahedra tilt angles range from 16–19°. All Al–Al bond lengths are 2.99 Å. There are six inequivalent C sites. In the first C site, C is bonded to six Ta atoms to form CTa6 octahedra that share corners with six AlTa3Al6V3 cuboctahedra, edges with six AlTa3Al6V3 cuboctahedra, and edges with six equivalent CTa6 octahedra. In the second C site, C is bonded to three equivalent Ta and three equivalent V atoms to form CTa3V3 octahedra that share corners with six AlTa3Al6V3 cuboctahedra, edges with six AlTa3Al6V3 cuboctahedra, and edges with six equivalent CTa3V3 octahedra. In the third C site, C is bonded to three equivalent Ta and three equivalent V atoms to form CTa3V3 octahedra that share corners with six AlTa3Al6V3 cuboctahedra, edges with six AlTa3Al6V3 cuboctahedra, and edges with six equivalent CTa3V3 octahedra. In the fourth C site, C is bonded to six V atoms to form CV6 octahedra that share corners with six AlTa3Al6V3 cuboctahedra, edges with six AlTa3Al6V3 cuboctahedra, and edges with six equivalent CV6 octahedra. In the fifth C site, C is bonded to six V atoms to form CV6 octahedra that share corners with six AlAl6V6 cuboctahedra, edges with six AlAl6V6 cuboctahedra, and edges with six equivalent CV6 octahedra. In the sixth C site, C is bonded to six V atoms to form CV6 octahedra that share corners with six AlTa3Al6V3 cuboctahedra, edges with six AlTa3Al6V3 cuboctahedra, and edges with six equivalent CV6 octahedra.