DOE OSTI2020
Fe19GaN5 crystallizes in the tetragonal P4/m space group. The structure is three-dimensional. there are six inequivalent Fe sites. In the first Fe site, Fe is bonded in a linear geometry to four equivalent Fe and two equivalent N atoms. All Fe–Fe bond lengths are 2.65 Å. Both Fe–N bond lengths are 1.90 Å. In the second Fe site, Fe is bonded in a linear geometry to three equivalent Fe, one Ga, and two equivalent N atoms. There are a spread of Fe–Fe bond distances ranging from 2.63–2.68 Å. The Fe–Ga bond length is 2.60 Å. Both Fe–N bond lengths are 1.90 Å. In the third Fe site, Fe is bonded in a linear geometry to four equivalent Fe and two N atoms. There are two shorter (2.65 Å) and two longer (2.69 Å) Fe–Fe bond lengths. There is one shorter (1.87 Å) and one longer (1.88 Å) Fe–N bond length. In the fourth Fe site, Fe is bonded in a linear geometry to two equivalent Fe, two equivalent Ga, and two equivalent N atoms. Both Fe–Fe bond lengths are 2.67 Å. Both Fe–Ga bond lengths are 2.66 Å. There is one shorter (1.86 Å) and one longer (1.87 Å) Fe–N bond length. In the fifth Fe site, Fe is bonded in a linear geometry to four equivalent Fe and two equivalent N atoms. All Fe–Fe bond lengths are 2.66 Å. Both Fe–N bond lengths are 1.88 Å. In the sixth Fe site, Fe is bonded to twelve Fe atoms to form FeFe12 cuboctahedra that share corners with three equivalent GaFe12 cuboctahedra, corners with nine equivalent FeFe12 cuboctahedra, a faceface with one GaFe12 cuboctahedra, faces with five equivalent FeFe12 cuboctahedra, and faces with eight NFe6 octahedra. Ga is bonded to twelve Fe atoms to form GaFe12 cuboctahedra that share corners with twelve equivalent FeFe12 cuboctahedra, faces with two equivalent GaFe12 cuboctahedra, faces with four equivalent FeFe12 cuboctahedra, and faces with eight equivalent NFe6 octahedra. There are two inequivalent N sites. In the first N site, N is bonded to six Fe atoms to form NFe6 octahedra that share corners with six NFe6 octahedra and faces with eight equivalent FeFe12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the second N site, N is bonded to six Fe atoms to form NFe6 octahedra that share corners with six NFe6 octahedra, faces with two equivalent GaFe12 cuboctahedra, and faces with six equivalent FeFe12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–2°.