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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on U(CrSi)2 by Materials Project

U(CrSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. U3+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All U–Si bond lengths are 3.02 Å. Cr+2.50+ is bonded to four equivalent Si4- atoms to form a mixture of corner and edge-sharing CrSi4 tetrahedra. All Cr–Si bond lengths are 2.39 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent U3+, four equivalent Cr+2.50+, and one Si4- atom. The Si–Si bond length is 2.38 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U2Cr3Si by Materials Project

U2Cr3Si crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. U is bonded in a 10-coordinate geometry to one U, nine Cr, and three equivalent Si atoms. The U–U bond length is 2.63 Å. There are a spread of U–Cr bond distances ranging from 2.87–3.07 Å. There are one shorter (3.02 Å) and two longer (3.03 Å) U–Si bond lengths. There are three inequivalent Cr sites. In the first Cr site, Cr is bonded to six equivalent U, four Cr, and two equivalent Si atoms to form distorted CrU6Cr4Si2 cuboctahedra that share corners with four equivalent SiU6Cr6 cuboctahedra, corners with fourteen CrU6Cr4Si2 cuboctahedra, edges with six equivalent CrU6Cr4Si2 cuboctahedra, faces with six equivalent SiU6Cr6 cuboctahedra, and faces with twelve CrU6Cr4Si2 cuboctahedra. There are a spread of Cr–Cr bond distances ranging from 2.46–2.64 Å. Both Cr–Si bond lengths are 2.53 Å. In the second Cr site, Cr is bonded to six equivalent U, four Cr, and two equivalent Si atoms to form distorted CrU6Cr4Si2 cuboctahedra that share corners with four equivalent SiU6Cr6 cuboctahedra, corners with fourteen CrU6Cr4Si2 cuboctahedra, edges with six equivalent CrU6Cr4Si2 cuboctahedra, faces with six equivalent SiU6Cr6 cuboctahedra, and faces with twelve CrU6Cr4Si2 cuboctahedra. There are one shorter (2.47 Å) and one longer (2.63 Å) Cr–Cr bond lengths. Both Cr–Si bond lengths are 2.53 Å. In the third Cr site, Cr is bonded to six equivalent U, four Cr, and two equivalent Si atoms to form distorted CrU6Cr4Si2 cuboctahedra that share corners with four equivalent SiU6Cr6 cuboctahedra, corners with fourteen CrU6Cr4Si2 cuboctahedra, edges with six equivalent CrU6Cr4Si2 cuboctahedra, faces with six equivalent SiU6Cr6 cuboctahedra, and faces with twelve CrU6Cr4Si2 cuboctahedra. Both Cr–Si bond lengths are 2.53 Å. Si is bonded to six equivalent U and six Cr atoms to form SiU6Cr6 cuboctahedra that share corners with twelve CrU6Cr4Si2 cuboctahedra, edges with six equivalent SiU6Cr6 cuboctahedra, faces with two equivalent SiU6Cr6 cuboctahedra, and faces with eighteen CrU6Cr4Si2 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U4Cr7Si by Materials Project

U4Cr7Si crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. there are two inequivalent U sites. In the first U site, U is bonded in a 12-coordinate geometry to four U and twelve Cr atoms. There are one shorter (2.98 Å) and three longer (3.13 Å) U–U bond lengths. There are a spread of U–Cr bond distances ranging from 2.94–3.01 Å. In the second U site, U is bonded in a 12-coordinate geometry to four U, nine equivalent Cr, and three equivalent Si atoms. All U–U bond lengths are 3.11 Å. There are six shorter (2.93 Å) and three longer (2.96 Å) U–Cr bond lengths. All U–Si bond lengths are 2.97 Å. There are two inequivalent Cr sites. In the first Cr site, Cr is bonded to six U, five Cr, and one Si atom to form distorted CrU6Cr5Si cuboctahedra that share corners with two equivalent SiU6Cr6 cuboctahedra, corners with sixteen CrU6Cr5Si cuboctahedra, edges with six equivalent CrU6Cr5Si cuboctahedra, faces with three equivalent SiU6Cr6 cuboctahedra, and faces with fifteen CrU6Cr5Si cuboctahedra. There are a spread of Cr–Cr bond distances ranging from 2.48–2.56 Å. The Cr–Si bond length is 2.52 Å. In the second Cr site, Cr is bonded to six equivalent U and six equivalent Cr atoms to form CrU6Cr6 cuboctahedra that share corners with twelve equivalent CrU6Cr5Si cuboctahedra, edges with six equivalent CrU6Cr6 cuboctahedra, faces with two equivalent SiU6Cr6 cuboctahedra, and faces with eighteen equivalent CrU6Cr5Si cuboctahedra. Si is bonded to six equivalent U and six equivalent Cr atoms to form SiU6Cr6 cuboctahedra that share corners with twelve equivalent CrU6Cr5Si cuboctahedra, edges with six equivalent SiU6Cr6 cuboctahedra, and faces with twenty CrU6Cr6 cuboctahedra.

36 MATERIALS SCIENCE↗