Materials Data on Cr3N4 by Materials Project

Cr3N4 is Corundum-like structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are three inequivalent Cr4+ sites. In the first Cr4+ site, Cr4+ is bonded to six N3- atoms to form CrN6 octahedra that share corners with four equivalent CrN6 octahedra, corners with two equivalent CrN4 tetrahedra, edges with four CrN6 octahedra, and edges with two equivalent CrN4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Cr–N bond distances ranging from 2.00–2.06 Å. In the second Cr4+ site, Cr4+ is bonded to six N3- atoms to form CrN6 octahedra that share corners with eight CrN6 octahedra, corners with four equivalent CrN4 tetrahedra, edges with two equivalent CrN6 octahedra, and an edgeedge with one CrN4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–55°. There are a spread of Cr–N bond distances ranging from 2.03–2.10 Å. In the third Cr4+ site, Cr4+ is bonded to four N3- atoms to form a mixture of edge and corner-sharing CrN4 tetrahedra. The corner-sharing octahedra tilt angles range from 57–62°. There are a spread of Cr–N bond distances ranging from 1.76–1.78 Å. There are three inequivalent N3- sites. In the first N3- site, N3- is bonded to four Cr4+ atoms to form distorted corner-sharing NCr4 trigonal pyramids. In the second N3- site, N3- is bonded in a rectangular see-saw-like geometry to four Cr4+ atoms. In the third N3- site, N3- is bonded in a rectangular see-saw-like geometry to four Cr4+ atoms.