Materials Data on NbFeSi2 by Materials Project

NbFeSi2 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. there are two inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded in a 8-coordinate geometry to eight Si4- atoms. There are a spread of Nb–Si bond distances ranging from 2.63–2.79 Å. In the second Nb5+ site, Nb5+ is bonded to seven Si4- atoms to form NbSi7 pentagonal bipyramids that share corners with two equivalent FeSi6 octahedra, corners with two equivalent NbSi7 pentagonal bipyramids, edges with three equivalent NbSi7 pentagonal bipyramids, and faces with two equivalent FeSi6 octahedra. The corner-sharing octahedral tilt angles are 52°. There are a spread of Nb–Si bond distances ranging from 2.61–2.80 Å. There are two inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded in a 6-coordinate geometry to six Si4- atoms. There are a spread of Fe–Si bond distances ranging from 2.29–2.41 Å. In the second Fe3+ site, Fe3+ is bonded to six Si4- atoms to form distorted FeSi6 octahedra that share corners with two equivalent NbSi7 pentagonal bipyramids, edges with two equivalent FeSi6 octahedra, and faces with two equivalent NbSi7 pentagonal bipyramids. There are a spread of Fe–Si bond distances ranging from 2.36–2.39 Å. There are five inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 2-coordinate geometry to four equivalent Nb5+, two equivalent Fe3+, and one Si4- atom. The Si–Si bond length is 2.46 Å. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to six Nb5+, two equivalent Fe3+, and one Si4- atom. The Si–Si bond length is 2.39 Å. In the third Si4- site, Si4- is bonded in a 6-coordinate geometry to two equivalent Nb5+ and four Fe3+ atoms. In the fourth Si4- site, Si4- is bonded in a 9-coordinate geometry to five Nb5+ and four Fe3+ atoms. In the fifth Si4- site, Si4- is bonded in a 7-coordinate geometry to three Nb5+, three Fe3+, and one Si4- atom. The Si–Si bond length is 2.34 Å.