Materials Data on LaFe8Si5 by Materials Project
LaFe8Si5 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. La3+ is bonded in a 10-coordinate geometry to ten Si4- atoms. There are a spread of La–Si bond distances ranging from 3.19–3.36 Å. There are seven inequivalent Fe+2.12+ sites. In the first Fe+2.12+ site, Fe+2.12+ is bonded to one Fe+2.12+ and four Si4- atoms to form distorted FeFeSi4 tetrahedra that share corners with two equivalent FeFe6Si6 cuboctahedra, corners with two equivalent FeFeSi4 tetrahedra, an edgeedge with one FeFe8Si4 cuboctahedra, an edgeedge with one FeFeSi4 tetrahedra, and a faceface with one FeFeSi4 tetrahedra. The Fe–Fe bond length is 2.48 Å. There are a spread of Fe–Si bond distances ranging from 2.34–2.40 Å. In the second Fe+2.12+ site, Fe+2.12+ is bonded in a 5-coordinate geometry to two Fe+2.12+ and five Si4- atoms. There are one shorter (2.49 Å) and one longer (2.51 Å) Fe–Fe bond lengths. There are a spread of Fe–Si bond distances ranging from 2.35–2.46 Å. In the third Fe+2.12+ site, Fe+2.12+ is bonded to six Fe+2.12+ and six Si4- atoms to form distorted corner-sharing FeFe6Si6 cuboctahedra. Both Fe–Fe bond lengths are 2.41 Å. There are two shorter (2.33 Å) and four longer (2.38 Å) Fe–Si bond lengths. In the fourth Fe+2.12+ site, Fe+2.12+ is bonded to eight Fe+2.12+ and four equivalent Si4- atoms to form distorted edge-sharing FeFe8Si4 cuboctahedra. There are two shorter (2.41 Å) and two longer (2.47 Å) Fe–Fe bond lengths. All Fe–Si bond lengths are 2.35 Å. In the fifth Fe+2.12+ site, Fe+2.12+ is bonded in a 9-coordinate geometry to three Fe+2.12+ and four Si4- atoms. There are one shorter (2.33 Å) and one longer (2.34 Å) Fe–Fe bond lengths. There are two shorter (2.47 Å) and two longer (2.53 Å) Fe–Si bond lengths. In the sixth Fe+2.12+ site, Fe+2.12+ is bonded in a 2-coordinate geometry to one Fe+2.12+ and six Si4- atoms. There are a spread of Fe–Si bond distances ranging from 2.31–2.60 Å. In the seventh Fe+2.12+ site, Fe+2.12+ is bonded in a 10-coordinate geometry to five Fe+2.12+ and five Si4- atoms. There are three shorter (2.51 Å) and two longer (2.53 Å) Fe–Si bond lengths. There are three inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 11-coordinate geometry to two equivalent La3+, eight Fe+2.12+, and one Si4- atom. The Si–Si bond length is 2.59 Å. In the second Si4- site, Si4- is bonded in a 11-coordinate geometry to two equivalent La3+, eight Fe+2.12+, and one Si4- atom. The Si–Si bond length is 2.58 Å. In the third Si4- site, Si4- is bonded in a 12-coordinate geometry to two equivalent La3+, six Fe+2.12+, and four Si4- atoms.