DOE OSTI2020
WFeSi crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are two inequivalent W2+ sites. In the first W2+ site, W2+ is bonded in a 5-coordinate geometry to five Si4- atoms. There are a spread of W–Si bond distances ranging from 2.71–2.80 Å. In the second W2+ site, W2+ is bonded in a 7-coordinate geometry to seven Si4- atoms. There are a spread of W–Si bond distances ranging from 2.75–2.79 Å. There are two inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded in a distorted hexagonal planar geometry to two equivalent Fe2+ and four Si4- atoms. Both Fe–Fe bond lengths are 2.43 Å. There are three shorter (2.30 Å) and one longer (2.37 Å) Fe–Si bond lengths. In the second Fe2+ site, Fe2+ is bonded in a 6-coordinate geometry to four Fe2+ and two equivalent Si4- atoms. There are one shorter (2.33 Å) and one longer (2.49 Å) Fe–Fe bond lengths. There are one shorter (2.36 Å) and one longer (2.44 Å) Fe–Si bond lengths. There are three inequivalent Si4- sites. In the first Si4- site, Si4- is bonded to six W2+ and six Fe2+ atoms to form SiFe6W6 cuboctahedra that share corners with fourteen SiFe6W6 cuboctahedra, edges with six SiFe6W6 cuboctahedra, and faces with four equivalent SiFe2Si4W6 cuboctahedra. In the second Si4- site, Si4- is bonded to six W2+, two equivalent Fe2+, and four Si4- atoms to form SiFe2Si4W6 cuboctahedra that share corners with eight SiFe6W6 cuboctahedra, edges with two equivalent SiFe2Si4W6 cuboctahedra, and faces with ten SiFe6W6 cuboctahedra. There are a spread of Si–Si bond distances ranging from 2.37–2.44 Å. In the third Si4- site, Si4- is bonded to six W2+, two equivalent Fe2+, and four equivalent Si4- atoms to form SiFe2Si4W6 cuboctahedra that share corners with six SiFe6W6 cuboctahedra, edges with six SiFe6W6 cuboctahedra, and faces with eight equivalent SiFe2Si4W6 cuboctahedra.