Materials Data on FeSiMo by Materials Project
FeMoSi crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are two inequivalent Mo2+ sites. In the first Mo2+ site, Mo2+ is bonded in a 7-coordinate geometry to seven Si4- atoms. There are a spread of Mo–Si bond distances ranging from 2.70–2.82 Å. In the second Mo2+ site, Mo2+ is bonded in a 5-coordinate geometry to five Si4- atoms. There are a spread of Mo–Si bond distances ranging from 2.65–2.85 Å. There are three inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded in a 6-coordinate geometry to four equivalent Fe2+ and two equivalent Si4- atoms. There are two shorter (2.26 Å) and two longer (2.43 Å) Fe–Fe bond lengths. Both Fe–Si bond lengths are 2.34 Å. 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 (2.34 Å) and one longer (2.55 Å) Fe–Fe bond lengths. Both Fe–Si bond lengths are 2.31 Å. In the third Fe2+ site, Fe2+ is bonded in a distorted hexagonal planar geometry to six Si4- atoms. There are a spread of Fe–Si bond distances ranging from 2.30–2.36 Å. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded to six Mo2+, two equivalent Fe2+, and four Si4- atoms to form a mixture of distorted corner, edge, and face-sharing SiFe2Si4Mo6 cuboctahedra. There are a spread of Si–Si bond distances ranging from 2.34–2.55 Å. In the second Si4- site, Si4- is bonded to six Mo2+, four Fe2+, and two equivalent Si4- atoms to form distorted SiFe4Si2Mo6 cuboctahedra that share corners with four equivalent SiFe2Si4Mo6 cuboctahedra, edges with six equivalent SiFe4Si2Mo6 cuboctahedra, and faces with eight SiFe2Si4Mo6 cuboctahedra.