Materials Data on SrMg2(GaN2)2 by Materials Project

Abstract

Sr(Mg2Ga2)N4 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. Sr2+ is bonded in a body-centered cubic geometry to eight N3- atoms. There are a spread of Sr–N bond distances ranging from 2.74–2.99 Å. There are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to four N3- atoms to form MgN4 trigonal pyramids that share corners with three equivalent GaN4 tetrahedra, corners with five MgN4 trigonal pyramids, and edges with two equivalent GaN4 tetrahedra. There are a spread of Mg–N bond distances ranging from 2.05–2.29 Å. In the second Mg2+ site, Mg2+ is bonded to four N3- atoms to form MgN4 trigonal pyramids that share corners with three equivalent GaN4 tetrahedra, corners with five MgN4 trigonal pyramids, and edges with two equivalent GaN4 tetrahedra. There are a spread of Mg–N bond distances ranging from 2.04–2.17 Å. There are two inequivalent Ga3+ sites. In the first Ga3+ site, Ga3+ is bonded to four N3- atoms to form GaN4 tetrahedra that share corners with five GaN4 tetrahedra, corners with three equivalent MgN4 trigonal pyramids, and edges with two equivalent MgN4 trigonal pyramids. There are a spread of Ga–N bond distances ranging from 1.94–2.04 Å. In the second Ga3+ site, Ga3+ is bonded to four N3- atoms to form GaN4 tetrahedra that share corners with five GaN4 tetrahedra, corners with three equivalent MgN4 trigonal pyramids, and edges with two equivalent MgN4 trigonal pyramids. There are a spread of Ga–N bond distances ranging from 1.96–2.09 Å. There are four inequivalent N3- sites. In the first N3- site, N3- is bonded in a 4-coordinate geometry to two equivalent Sr2+, one Mg2+, and three Ga3+ atoms. In the second N3- site, N3- is bonded to two equivalent Sr2+, three Mg2+, and one Ga3+ atom to form distorted edge-sharing NSr2Mg3Ga octahedra. In the third N3- site, N3- is bonded in a 4-coordinate geometry to two equivalent Sr2+, two Mg2+, and two equivalent Ga3+ atoms. In the fourth N3- site, N3- is bonded in a 6-coordinate geometry to two equivalent Sr2+, two equivalent Mg2+, and two Ga3+ atoms.