DOI: 10.17188/1683438
title: Materials Data on Ta3(CrSi)8 by Materials Project

description: Ta3(CrSi)8 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are three inequivalent Ta3+ sites. In the first Ta3+ site, Ta3+ is bonded to seven Si4- atoms to form TaSi7 pentagonal bipyramids that share corners with seven TaSi7 pentagonal bipyramids, corners with two equivalent CrSi6 pentagonal pyramids, an edgeedge with one TaSi7 pentagonal bipyramid, edges with two equivalent CrSi6 pentagonal pyramids, and faces with two equivalent CrSi6 pentagonal pyramids. There are a spread of Ta–Si bond distances ranging from 2.57–2.67 Å. In the second Ta3+ site, Ta3+ is bonded to seven Si4- atoms to form TaSi7 pentagonal bipyramids that share corners with four TaSi7 pentagonal bipyramids, corners with four CrSi6 pentagonal pyramids, edges with three TaSi7 pentagonal bipyramids, faces with two equivalent TaSi7 pentagonal bipyramids, and faces with two equivalent CrSi6 pentagonal pyramids. There are a spread of Ta–Si bond distances ranging from 2.53–2.67 Å. In the third Ta3+ site, Ta3+ is bonded to seven Si4- atoms to form TaSi7 pentagonal bipyramids that share corners with seven TaSi7 pentagonal bipyramids, edges with three equivalent CrSi6 pentagonal pyramids, faces with two equivalent TaSi7 pentagonal bipyramids, and a faceface with one CrSi6 pentagonal pyramid. There are a spread of Ta–Si bond distances ranging from 2.63–2.73 Å. There are six inequivalent Cr+2.88+ sites. In the first Cr+2.88+ site, Cr+2.88+ is bonded in a 6-coordinate geometry to six Si4- atoms. There are a spread of Cr–Si bond distances ranging from 2.36–2.75 Å. In the second Cr+2.88+ site, Cr+2.88+ is bonded in a 6-coordinate geometry to six Si4- atoms. There are a spread of Cr–Si bond distances ranging from 2.45–2.72 Å. In the third Cr+2.88+ site, Cr+2.88+ is bonded to six Si4- atoms to form CrSi6 pentagonal pyramids that share corners with three equivalent TaSi7 pentagonal bipyramids, corners with three CrSi6 pentagonal pyramids, edges with three equivalent TaSi7 pentagonal bipyramids, an edgeedge with one CrSi6 pentagonal pyramid, and faces with two equivalent TaSi7 pentagonal bipyramids. There are a spread of Cr–Si bond distances ranging from 2.35–2.58 Å. In the fourth Cr+2.88+ site, Cr+2.88+ is bonded in a 7-coordinate geometry to two equivalent Cr+2.88+ and five Si4- atoms. There are one shorter (2.34 Å) and one longer (2.47 Å) Cr–Cr bond lengths. There are a spread of Cr–Si bond distances ranging from 2.42–2.47 Å. In the fifth Cr+2.88+ site, Cr+2.88+ is bonded in a 8-coordinate geometry to two equivalent Cr+2.88+ and six Si4- atoms. There are one shorter (2.31 Å) and one longer (2.51 Å) Cr–Cr bond lengths. There are a spread of Cr–Si bond distances ranging from 2.49–2.58 Å. In the sixth Cr+2.88+ site, Cr+2.88+ is bonded to six Si4- atoms to form CrSi6 pentagonal pyramids that share corners with three TaSi7 pentagonal bipyramids, corners with three CrSi6 pentagonal pyramids, edges with two equivalent TaSi7 pentagonal bipyramids, an edgeedge with one CrSi6 pentagonal pyramid, and faces with three TaSi7 pentagonal bipyramids. There are a spread of Cr–Si bond distances ranging from 2.38–2.58 Å. There are seven inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 10-coordinate geometry to two Ta3+ and eight Cr+2.88+ atoms. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to three Ta3+ and six Cr+2.88+ atoms. In the third Si4- site, Si4- is bonded in a 9-coordinate geometry to two equivalent Ta3+ and seven Cr+2.88+ atoms. In the fourth Si4- site, Si4- is bonded in a 9-coordinate geometry to three Ta3+, four Cr+2.88+, and two equivalent Si4- atoms. There are one shorter (2.40 Å) and one longer (2.41 Å) Si–Si bond lengths. In the fifth Si4- site, Si4- is bonded in a 9-coordinate geometry to four Ta3+ and five Cr+2.88+ atoms. In the sixth Si4- site, Si4- is bonded in a 8-coordinate geometry to two Ta3+ and six Cr+2.88+ atoms. In the seventh Si4- site, Si4- is bonded in a 8-coordinate geometry to two Ta3+ and six Cr+2.88+ atoms.