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DOE OSTI2020

Materials Data on Ta2Cr4Si5 by Materials Project

Ta2Cr4Si5 crystallizes in the orthorhombic Ibam space group. The structure is three-dimensional. Ta4+ is bonded to six Si4- atoms to form TaSi6 octahedra that share corners with four equivalent TaSi6 octahedra, corners with six equivalent CrSi7 pentagonal bipyramids, edges with two equivalent TaSi6 octahedra, faces with two equivalent TaSi6 octahedra, and faces with four equivalent CrSi7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 39°. There are a spread of Ta–Si bond distances ranging from 2.57–2.65 Å. There are two inequivalent Cr3+ sites. In the first Cr3+ site, Cr3+ is bonded in a 7-coordinate geometry to seven Si4- atoms. There are a spread of Cr–Si bond distances ranging from 2.30–2.84 Å. In the second Cr3+ site, Cr3+ is bonded to seven Si4- atoms to form CrSi7 pentagonal bipyramids that share corners with six equivalent TaSi6 octahedra, corners with six equivalent CrSi7 pentagonal bipyramids, edges with three equivalent CrSi7 pentagonal bipyramids, faces with four equivalent TaSi6 octahedra, and faces with two equivalent CrSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 39–55°. There are a spread of Cr–Si bond distances ranging from 2.53–2.86 Å. There are three inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 10-coordinate geometry to eight Cr3+ and two equivalent Si4- atoms. Both Si–Si bond lengths are 2.58 Å. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent Ta4+ and five Cr3+ atoms. In the third Si4- site, Si4- is bonded in a 8-coordinate geometry to two equivalent Ta4+, five Cr3+, and one Si4- atom. The Si–Si bond length is 2.37 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2CrSi6 by Materials Project

Ta2CrSi6 is Titanium Disilicide-derived structured and crystallizes in the orthorhombic C222 space group. The structure is three-dimensional. Ta3+ is bonded in a distorted q6 geometry to ten Si+1.33- atoms. There are a spread of Ta–Si bond distances ranging from 2.59–2.76 Å. Cr2+ is bonded in a distorted q6 geometry to ten Si+1.33- atoms. There are a spread of Cr–Si bond distances ranging from 2.51–2.82 Å. There are two inequivalent Si+1.33- sites. In the first Si+1.33- site, Si+1.33- is bonded in a 10-coordinate geometry to two equivalent Ta3+, three equivalent Cr2+, and five Si+1.33- atoms. There are a spread of Si–Si bond distances ranging from 2.50–2.78 Å. In the second Si+1.33- site, Si+1.33- is bonded in a 10-coordinate geometry to four equivalent Ta3+, one Cr2+, and five Si+1.33- atoms. There are a spread of Si–Si bond distances ranging from 2.61–2.87 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta3Cr8Si by Materials Project

Ta3Cr8Si 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 6-coordinate geometry to one Ta, twelve Cr, and three equivalent Si atoms. The Ta–Ta bond length is 3.05 Å. There are a spread of Ta–Cr bond distances ranging from 2.78–2.86 Å. All Ta–Si bond lengths are 2.96 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 2.97 Å. There are a spread of Ta–Cr bond distances ranging from 2.84–2.87 Å. In the third Ta site, Ta is bonded in a 1-coordinate geometry to three equivalent Ta, twelve Cr, and one Si atom. There are a spread of Ta–Cr bond distances ranging from 2.84–2.89 Å. The Ta–Si bond length is 2.94 Å. There are four inequivalent Cr sites. In the first Cr site, Cr is bonded to three equivalent Ta, six Cr, and three equivalent Si atoms to form CrTa3Cr6Si3 cuboctahedra that share corners with twelve CrTa4Cr6Si2 cuboctahedra, edges with six equivalent CrTa3Cr6Si3 cuboctahedra, and faces with twenty CrTa6Cr6 cuboctahedra. There are three shorter (2.42 Å) and three longer (2.44 Å) Cr–Cr bond lengths. All Cr–Si bond lengths are 2.84 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 CrTa4Cr6Si2 cuboctahedra, edges with six equivalent CrTa6Cr6 cuboctahedra, and faces with twenty CrTa3Cr6Si3 cuboctahedra. All Cr–Cr bond lengths are 2.47 Å. In the third Cr site, Cr is bonded to four Ta, six Cr, and two equivalent Si atoms to form CrTa4Cr6Si2 cuboctahedra that share corners with eighteen CrTa3Cr6Si3 cuboctahedra, edges with six CrTa5Cr6Si cuboctahedra, and faces with eighteen CrTa3Cr6Si3 cuboctahedra. There are two shorter (2.38 Å) and two longer (2.46 Å) Cr–Cr bond lengths. Both Cr–Si bond lengths are 2.83 Å. In the fourth Cr site, Cr is bonded to five Ta, six Cr, and one Si atom to form CrTa5Cr6Si cuboctahedra that share corners with eighteen CrTa3Cr6Si3 cuboctahedra, edges with six CrTa5Cr6Si cuboctahedra, and faces with eighteen CrTa3Cr6Si3 cuboctahedra. There are two shorter (2.35 Å) and two longer (2.49 Å) Cr–Cr bond lengths. The Cr–Si bond length is 2.82 Å. Si is bonded in a 10-coordinate geometry to four Ta and twelve Cr atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2Cr3Si by Materials Project

Ta2Cr3Si crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ta is bonded in a 12-coordinate geometry to four equivalent Ta, nine equivalent Cr, and three equivalent Si atoms. All Ta–Ta bond lengths are 3.00 Å. There are six shorter (2.86 Å) and three longer (2.89 Å) Ta–Cr bond lengths. All Ta–Si bond lengths are 2.86 Å. Cr is bonded to six equivalent Ta, four equivalent Cr, and two equivalent Si atoms to form distorted CrTa6Cr4Si2 cuboctahedra that share corners with four equivalent SiTa6Cr6 cuboctahedra, corners with fourteen equivalent CrTa6Cr4Si2 cuboctahedra, edges with six equivalent CrTa6Cr4Si2 cuboctahedra, faces with six equivalent SiTa6Cr6 cuboctahedra, and faces with twelve equivalent CrTa6Cr4Si2 cuboctahedra. There are two shorter (2.36 Å) and two longer (2.51 Å) Cr–Cr bond lengths. Both Cr–Si bond lengths are 2.49 Å. Si is bonded to six equivalent Ta and six equivalent Cr atoms to form SiTa6Cr6 cuboctahedra that share corners with twelve equivalent CrTa6Cr4Si2 cuboctahedra, edges with six equivalent SiTa6Cr6 cuboctahedra, faces with two equivalent SiTa6Cr6 cuboctahedra, and faces with eighteen equivalent CrTa6Cr4Si2 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TaCr4Si by Materials Project

TaCr4Si crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Ta is bonded in a 1-coordinate geometry to three equivalent Ta, twelve Cr, and one Si atom. All Ta–Ta bond lengths are 2.99 Å. There are three shorter (2.85 Å) and nine longer (2.86 Å) Ta–Cr bond lengths. The Ta–Si bond length is 2.79 Å. There are three inequivalent Cr sites. In the first Cr site, Cr is bonded to six equivalent Cr and six equivalent Si atoms to form CrCr6Si6 cuboctahedra that share corners with twelve equivalent CrTa3Cr6Si3 cuboctahedra, edges with six equivalent CrCr6Si6 cuboctahedra, and faces with twenty CrTa6Cr6 cuboctahedra. All Cr–Cr bond lengths are 2.33 Å. All Cr–Si bond lengths are 2.86 Å. In the second Cr site, Cr is bonded to six equivalent Ta and six equivalent Cr atoms to form CrTa6Cr6 cuboctahedra that share corners with twelve equivalent CrTa3Cr6Si3 cuboctahedra, edges with six equivalent CrTa6Cr6 cuboctahedra, and faces with twenty CrCr6Si6 cuboctahedra. All Cr–Cr bond lengths are 2.47 Å. In the third Cr site, Cr is bonded to three equivalent Ta, six Cr, and three equivalent Si atoms to form CrTa3Cr6Si3 cuboctahedra that share corners with eighteen CrCr6Si6 cuboctahedra, edges with six equivalent CrTa3Cr6Si3 cuboctahedra, and faces with eighteen CrCr6Si6 cuboctahedra. There are two shorter (2.36 Å) and two longer (2.51 Å) Cr–Cr bond lengths. There are one shorter (2.71 Å) and two longer (2.76 Å) Cr–Si bond lengths. Si is bonded in a 10-coordinate geometry to one Ta and twelve Cr atoms.

36 MATERIALS SCIENCE↗