DOE OSTI2020
Ca3(GaN2)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six N3- atoms to form distorted CaN6 octahedra that share corners with seven CaN6 octahedra, corners with six equivalent GaN4 tetrahedra, edges with six equivalent CaN6 octahedra, edges with three equivalent GaN4 tetrahedra, and a faceface with one CaN6 octahedra. The corner-sharing octahedra tilt angles range from 13–63°. There are a spread of Ca–N bond distances ranging from 2.42–2.95 Å. In the second Ca2+ site, Ca2+ is bonded to six N3- atoms to form CaN6 octahedra that share corners with ten equivalent CaN6 octahedra, corners with four equivalent GaN4 tetrahedra, edges with two equivalent CaN6 octahedra, edges with four equivalent GaN4 tetrahedra, and faces with two equivalent CaN6 octahedra. The corner-sharing octahedra tilt angles range from 31–63°. There are a spread of Ca–N bond distances ranging from 2.43–2.62 Å. Ga3+ is bonded to four N3- atoms to form GaN4 tetrahedra that share corners with eight CaN6 octahedra, corners with two equivalent GaN4 tetrahedra, edges with five CaN6 octahedra, and an edgeedge with one GaN4 tetrahedra. The corner-sharing octahedra tilt angles range from 21–81°. There are a spread of Ga–N bond distances ranging from 1.97–2.07 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a 6-coordinate geometry to four Ca2+ and two equivalent Ga3+ atoms. In the second N3- site, N3- is bonded in a 7-coordinate geometry to five Ca2+ and two equivalent Ga3+ atoms.