Materials Data on U2Fe3Si by Materials Project
U2Fe3Si is Frank-Kasper $\mu$ Phase-derived structured and crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. U is bonded in a 9-coordinate geometry to one U, nine Fe, and three equivalent Si atoms. The U–U bond length is 2.74 Å. There are a spread of U–Fe bond distances ranging from 2.78–2.92 Å. All U–Si bond lengths are 3.01 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded to six equivalent U, four Fe, and two equivalent Si atoms to form distorted FeU6Fe4Si2 cuboctahedra that share corners with four equivalent SiU6Fe6 cuboctahedra, corners with fourteen FeU6Fe4Si2 cuboctahedra, edges with six equivalent FeU6Fe4Si2 cuboctahedra, faces with six equivalent SiU6Fe6 cuboctahedra, and faces with twelve FeU6Fe4Si2 cuboctahedra. There are a spread of Fe–Fe bond distances ranging from 2.55–2.58 Å. Both Fe–Si bond lengths are 2.38 Å. In the second Fe site, Fe is bonded to six equivalent U, four equivalent Fe, and two equivalent Si atoms to form distorted FeU6Fe4Si2 cuboctahedra that share corners with four equivalent SiU6Fe6 cuboctahedra, corners with fourteen FeU6Fe4Si2 cuboctahedra, edges with six equivalent FeU6Fe4Si2 cuboctahedra, faces with six equivalent SiU6Fe6 cuboctahedra, and faces with twelve equivalent FeU6Fe4Si2 cuboctahedra. Both Fe–Si bond lengths are 2.39 Å. Si is bonded to six equivalent U and six Fe atoms to form SiU6Fe6 cuboctahedra that share corners with twelve FeU6Fe4Si2 cuboctahedra, edges with six equivalent SiU6Fe6 cuboctahedra, faces with two equivalent SiU6Fe6 cuboctahedra, and faces with eighteen FeU6Fe4Si2 cuboctahedra.