Materials Data on Nb2Co2Si3 by Materials Project

Abstract

Nb2Co2Si3 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Nb4+ sites. In the first Nb4+ site, Nb4+ is bonded to seven Si4- atoms to form distorted NbSi7 pentagonal bipyramids that share corners with two equivalent SiCo8Si4 cuboctahedra, corners with two equivalent NbSi7 pentagonal bipyramids, corners with six equivalent NbSi6 pentagonal pyramids, edges with three equivalent NbSi7 pentagonal bipyramids, faces with two equivalent NbSi7 pentagonal bipyramids, and faces with four equivalent NbSi6 pentagonal pyramids. There are a spread of Nb–Si bond distances ranging from 2.52–2.87 Å. In the second Nb4+ site, Nb4+ is bonded to six Si4- atoms to form distorted NbSi6 pentagonal pyramids that share corners with two equivalent SiCo8Si4 cuboctahedra, corners with six equivalent NbSi7 pentagonal bipyramids, corners with two equivalent NbSi6 pentagonal pyramids, an edgeedge with one NbSi6 pentagonal pyramid, faces with four equivalent NbSi7 pentagonal bipyramids, and faces with two equivalent NbSi6 pentagonal pyramids. There are a spread of Nb–Si bond distances ranging from 2.62–2.79 Å. Co2+ is bonded in a 6-coordinate geometry to six Si4- atoms. There are a spread of Co–Si bond distances ranging from 2.27–2.69 Å. There are four inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 10-coordinate geometry to eight Nb4+ and two equivalent Si4- atoms. There are one shorter (2.47 Å) and one longer (2.59 Å) Si–Si bond lengths. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to five Nb4+ and four equivalent Co2+ atoms. In the third Si4- site, Si4- is bonded in a 9-coordinate geometry to four Nb4+, four equivalent Co2+, and one Si4- atom. The Si–Si bond length is 2.54 Å. In the fourth Si4- site, Si4- is bonded to eight equivalent Co2+ and four Si4- atoms to form SiCo8Si4 cuboctahedra that share corners with two equivalent SiCo8Si4 cuboctahedra, corners with four equivalent NbSi7 pentagonal bipyramids, corners with four equivalent NbSi6 pentagonal pyramids, and faces with two equivalent SiCo8Si4 cuboctahedra. Both Si–Si bond lengths are 2.53 Å.