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DOE OSTI2020

Materials Data on Sc2Nb3Si4 by Materials Project

Sc2Nb3Si4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Sc2+ is bonded to seven Si4- atoms to form distorted ScSi7 pentagonal bipyramids that share corners with four equivalent NbSi6 octahedra, corners with six equivalent ScSi7 pentagonal bipyramids, corners with five equivalent NbSi6 pentagonal pyramids, edges with two equivalent ScSi7 pentagonal bipyramids, edges with three equivalent NbSi6 pentagonal pyramids, faces with two equivalent NbSi6 octahedra, faces with three equivalent ScSi7 pentagonal bipyramids, and faces with three equivalent NbSi6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 46–52°. There are a spread of Sc–Si bond distances ranging from 2.75–2.99 Å. There are two inequivalent Nb4+ sites. In the first Nb4+ site, Nb4+ is bonded to six Si4- atoms to form distorted NbSi6 pentagonal pyramids that share corners with three equivalent NbSi6 octahedra, corners with five equivalent ScSi7 pentagonal bipyramids, corners with four equivalent NbSi6 pentagonal pyramids, edges with three equivalent ScSi7 pentagonal bipyramids, edges with three equivalent NbSi6 pentagonal pyramids, faces with two equivalent NbSi6 octahedra, faces with three equivalent ScSi7 pentagonal bipyramids, and a faceface with one NbSi6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 38–39°. There are a spread of Nb–Si bond distances ranging from 2.58–2.73 Å. In the second Nb4+ site, Nb4+ is bonded to six Si4- atoms to form NbSi6 octahedra that share corners with four equivalent NbSi6 octahedra, corners with eight equivalent ScSi7 pentagonal bipyramids, corners with six equivalent NbSi6 pentagonal pyramids, faces with four equivalent ScSi7 pentagonal bipyramids, and faces with four equivalent NbSi6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 49–56°. There are a spread of Nb–Si bond distances ranging from 2.65–2.79 Å. There are three inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent Sc2+, four Nb4+, and one Si4- atom. The Si–Si bond length is 2.44 Å. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent Sc2+, four Nb4+, and one Si4- atom. The Si–Si bond length is 2.55 Å. In the third Si4- site, Si4- is bonded in a 9-coordinate geometry to two equivalent Sc2+, six Nb4+, and one Si4- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc2(NbSi)3 by Materials Project

Sc2(NbSi)3 crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are three inequivalent Sc3+ sites. In the first Sc3+ site, Sc3+ is bonded to five Si4- atoms to form distorted ScSi5 trigonal bipyramids that share corners with eight equivalent NbSi6 octahedra, corners with eight ScSi5 trigonal bipyramids, edges with two equivalent ScSi5 trigonal bipyramids, edges with four equivalent NbSi5 trigonal bipyramids, and faces with four equivalent NbSi6 octahedra. The corner-sharing octahedra tilt angles range from 42–55°. There are a spread of Sc–Si bond distances ranging from 2.68–2.90 Å. In the second Sc3+ site, Sc3+ is bonded to five Si4- atoms to form distorted ScSi5 trigonal bipyramids that share corners with eight equivalent NbSi6 octahedra, corners with eight ScSi5 trigonal bipyramids, edges with two equivalent ScSi5 trigonal bipyramids, edges with four equivalent NbSi5 trigonal bipyramids, and faces with four equivalent NbSi6 octahedra. The corner-sharing octahedra tilt angles range from 42–55°. There are a spread of Sc–Si bond distances ranging from 2.67–2.90 Å. In the third Sc3+ site, Sc3+ is bonded to five Si4- atoms to form distorted ScSi5 trigonal bipyramids that share corners with eight equivalent NbSi6 octahedra, corners with two equivalent ScSi5 trigonal bipyramids, corners with six equivalent NbSi5 trigonal bipyramids, edges with six ScSi5 trigonal bipyramids, and faces with four equivalent NbSi6 octahedra. The corner-sharing octahedra tilt angles range from 41–56°. There are a spread of Sc–Si bond distances ranging from 2.68–2.91 Å. There are two inequivalent Nb2+ sites. In the first Nb2+ site, Nb2+ is bonded to five Si4- atoms to form distorted NbSi5 trigonal bipyramids that share corners with eight equivalent NbSi6 octahedra, corners with three equivalent ScSi5 trigonal bipyramids, corners with five equivalent NbSi5 trigonal bipyramids, edges with six ScSi5 trigonal bipyramids, and faces with four equivalent NbSi6 octahedra. The corner-sharing octahedra tilt angles range from 39–56°. There are a spread of Nb–Si bond distances ranging from 2.66–2.87 Å. In the second Nb2+ site, Nb2+ is bonded to six Si4- atoms to form distorted NbSi6 octahedra that share corners with six equivalent NbSi6 octahedra, corners with four equivalent NbSi5 trigonal bipyramids, corners with eight ScSi5 trigonal bipyramids, edges with three equivalent NbSi6 octahedra, faces with two equivalent NbSi6 octahedra, faces with two equivalent NbSi5 trigonal bipyramids, and faces with four ScSi5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 34–36°. There are a spread of Nb–Si bond distances ranging from 2.72–2.76 Å. There are four inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 9-coordinate geometry to five Sc3+ and four equivalent Nb2+ atoms. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to three Sc3+ and six Nb2+ atoms. In the third Si4- site, Si4- is bonded in a 9-coordinate geometry to three Sc3+ and six Nb2+ atoms. In the fourth Si4- site, Si4- is bonded in a 9-coordinate geometry to three Sc3+ and six Nb2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sc3(NbSi2)2 by Materials Project

Sc3(NbSi2)2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Sc3+ sites. In the first Sc3+ site, Sc3+ is bonded to six Si4- atoms to form distorted ScSi6 octahedra that share corners with four equivalent ScSi6 octahedra, corners with eight equivalent NbSi7 pentagonal bipyramids, and faces with four equivalent NbSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 50–58°. There are a spread of Sc–Si bond distances ranging from 2.62–3.01 Å. In the second Sc3+ site, Sc3+ is bonded in a 6-coordinate geometry to six Si4- atoms. There are a spread of Sc–Si bond distances ranging from 2.59–2.77 Å. Nb+3.50+ is bonded to seven Si4- atoms to form distorted NbSi7 pentagonal bipyramids that share corners with four equivalent ScSi6 octahedra, corners with six equivalent NbSi7 pentagonal bipyramids, edges with two equivalent NbSi7 pentagonal bipyramids, faces with two equivalent ScSi6 octahedra, and faces with three equivalent NbSi7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 47–50°. There are a spread of Nb–Si bond distances ranging from 2.74–3.03 Å. There are three inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 9-coordinate geometry to six Sc3+, two equivalent Nb+3.50+, and one Si4- atom. The Si–Si bond length is 2.37 Å. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to four Sc3+, four equivalent Nb+3.50+, and one Si4- atom. In the third Si4- site, Si4- is bonded in a 9-coordinate geometry to four Sc3+, four equivalent Nb+3.50+, and one Si4- atom. The Si–Si bond length is 2.59 Å.

36 MATERIALS SCIENCE↗