Materials Data on Ta2Cr4Si5 by Materials Project
Ta2Cr4Si5 crystallizes in the orthorhombic Ibam space group. The structure is three-dimensional. Ta4+ is bonded to six Si4- atoms to form TaSi6 octahedra that share corners with four equivalent TaSi6 octahedra, corners with six equivalent CrSi7 pentagonal bipyramids, edges with two equivalent TaSi6 octahedra, faces with two equivalent TaSi6 octahedra, and faces with four equivalent CrSi7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 39°. There are a spread of Ta–Si bond distances ranging from 2.57–2.65 Å. There are two inequivalent Cr3+ sites. In the first Cr3+ site, Cr3+ is bonded in a 7-coordinate geometry to seven Si4- atoms. There are a spread of Cr–Si bond distances ranging from 2.30–2.84 Å. In the second Cr3+ site, Cr3+ is bonded to seven Si4- atoms to form CrSi7 pentagonal bipyramids that share corners with six equivalent TaSi6 octahedra, corners with six equivalent CrSi7 pentagonal bipyramids, edges with three equivalent CrSi7 pentagonal bipyramids, faces with four equivalent TaSi6 octahedra, and faces with two equivalent CrSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 39–55°. There are a spread of Cr–Si bond distances ranging from 2.53–2.86 Å. There are three inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 10-coordinate geometry to eight Cr3+ and two equivalent Si4- atoms. Both Si–Si bond lengths are 2.58 Å. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent Ta4+ and five Cr3+ atoms. In the third Si4- site, Si4- is bonded in a 8-coordinate geometry to two equivalent Ta4+, five Cr3+, and one Si4- atom. The Si–Si bond length is 2.37 Å.