Materials Data on Ta3AlCr8 by Materials Project

Abstract

Ta3Cr8Al is Hexagonal Laves-derived structured and crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. there are three inequivalent Ta sites. In the first Ta site, Ta is bonded in a 12-coordinate geometry to one Ta, twelve Cr, and three equivalent Al atoms. The Ta–Ta bond length is 3.04 Å. There are a spread of Ta–Cr bond distances ranging from 2.82–2.87 Å. All Ta–Al bond lengths are 2.97 Å. In the second Ta site, Ta is bonded in a 12-coordinate geometry to four Ta and twelve Cr atoms. All Ta–Ta bond lengths are 2.98 Å. There are six shorter (2.85 Å) and six longer (2.87 Å) Ta–Cr bond lengths. In the third Ta site, Ta is bonded in a 12-coordinate geometry to three equivalent Ta, twelve Cr, and one Al atom. There are three shorter (2.85 Å) and nine longer (2.86 Å) Ta–Cr bond lengths. The Ta–Al bond length is 2.98 Å. There are four inequivalent Cr sites. In the first Cr site, Cr is bonded to three equivalent Ta, six Cr, and three equivalent Al atoms to form CrTa3Al3Cr6 cuboctahedra that share corners with twelve CrTa4Al2Cr6 cuboctahedra, edges with six equivalent CrTa3Al3Cr6 cuboctahedra, and faces with twenty CrTa6Cr6 cuboctahedra. All Cr–Cr bond lengths are 2.45 Å. All Cr–Al bond lengths are 2.85 Å. In the second Cr site, Cr is bonded to six Ta and six Cr atoms to form CrTa6Cr6 cuboctahedra that share corners with twelve CrTa4Al2Cr6 cuboctahedra, edges with six equivalent CrTa6Cr6 cuboctahedra, and faces with twenty CrTa3Al3Cr6 cuboctahedra. There are three shorter (2.46 Å) and three longer (2.48 Å) Cr–Cr bond lengths. In the third Cr site, Cr is bonded to four Ta, six Cr, and two equivalent Al atoms to form CrTa4Al2Cr6 cuboctahedra that share corners with eighteen CrTa3Al3Cr6 cuboctahedra, edges with six CrTa5AlCr6 cuboctahedra, and faces with eighteen CrTa3Al3Cr6 cuboctahedra. There are two shorter (2.39 Å) and two longer (2.47 Å) Cr–Cr bond lengths. Both Cr–Al bond lengths are 2.85 Å. In the fourth Cr site, Cr is bonded to five Ta, six Cr, and one Al atom to form CrTa5AlCr6 cuboctahedra that share corners with eighteen CrTa3Al3Cr6 cuboctahedra, edges with six CrTa5AlCr6 cuboctahedra, and faces with eighteen CrTa3Al3Cr6 cuboctahedra. There are two shorter (2.37 Å) and two longer (2.49 Å) Cr–Cr bond lengths. The Cr–Al bond length is 2.85 Å. Al is bonded in a 6-coordinate geometry to four Ta and twelve Cr atoms.