Materials Data on Nb5SiB2 by Materials Project
Nb5SiB2 crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. there are two inequivalent Nb2+ sites. In the first Nb2+ site, Nb2+ is bonded to four equivalent B3- and two equivalent Si4- atoms to form distorted NbSi2B4 octahedra that share corners with six equivalent NbSi2B4 octahedra, corners with sixteen equivalent NbSi2B3 trigonal bipyramids, and faces with eight equivalent NbSi2B3 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 0–57°. All Nb–B bond lengths are 2.53 Å. Both Nb–Si bond lengths are 2.92 Å. In the second Nb2+ site, Nb2+ is bonded to three equivalent B3- and two equivalent Si4- atoms to form NbSi2B3 trigonal bipyramids that share corners with four equivalent NbSi2B4 octahedra, corners with twelve equivalent NbSi2B3 trigonal bipyramids, edges with seven equivalent NbSi2B3 trigonal bipyramids, faces with two equivalent NbSi2B4 octahedra, and a faceface with one NbSi2B3 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 42–61°. There are two shorter (2.42 Å) and one longer (2.51 Å) Nb–B bond lengths. Both Nb–Si bond lengths are 2.68 Å. B3- is bonded in a 9-coordinate geometry to eight Nb2+ and one B3- atom. The B–B bond length is 2.01 Å. Si4- is bonded in a 10-coordinate geometry to ten Nb2+ atoms.