DOI: 10.17188/1321170
title: Materials Data on MgNiO2 by Materials Project

description: MgNiO2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 trigonal bipyramids that share corners with six NiO5 trigonal bipyramids, an edgeedge with one NiO5 trigonal bipyramid, edges with two equivalent MgO5 trigonal bipyramids, and a faceface with one NiO5 trigonal bipyramid. There are a spread of Mg–O bond distances ranging from 2.02–2.14 Å. In the second Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 trigonal bipyramids that share corners with six NiO5 trigonal bipyramids, an edgeedge with one NiO5 trigonal bipyramid, edges with two equivalent MgO5 trigonal bipyramids, and a faceface with one NiO5 trigonal bipyramid. There are a spread of Mg–O bond distances ranging from 2.02–2.14 Å. In the third Mg2+ site, Mg2+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Mg–O bond distances ranging from 1.93–2.00 Å. In the fourth Mg2+ site, Mg2+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Mg–O bond distances ranging from 1.93–2.00 Å. There are four inequivalent Ni2+ sites. In the first Ni2+ site, Ni2+ is bonded to five O2- atoms to form distorted NiO5 trigonal bipyramids that share corners with four MgO5 trigonal bipyramids, corners with four NiO5 trigonal bipyramids, an edgeedge with one MgO5 trigonal bipyramid, and edges with two equivalent NiO5 trigonal bipyramids. There are a spread of Ni–O bond distances ranging from 1.95–2.22 Å. In the second Ni2+ site, Ni2+ is bonded to five O2- atoms to form distorted NiO5 trigonal bipyramids that share corners with two equivalent MgO5 trigonal bipyramids, corners with four NiO5 trigonal bipyramids, edges with two equivalent NiO5 trigonal bipyramids, and a faceface with one MgO5 trigonal bipyramid. There are a spread of Ni–O bond distances ranging from 1.98–2.15 Å. In the third Ni2+ site, Ni2+ is bonded to five O2- atoms to form distorted NiO5 trigonal bipyramids that share corners with two equivalent MgO5 trigonal bipyramids, corners with four NiO5 trigonal bipyramids, edges with two equivalent NiO5 trigonal bipyramids, and a faceface with one MgO5 trigonal bipyramid. There are a spread of Ni–O bond distances ranging from 1.98–2.17 Å. In the fourth Ni2+ site, Ni2+ is bonded to five O2- atoms to form distorted NiO5 trigonal bipyramids that share corners with four MgO5 trigonal bipyramids, corners with four NiO5 trigonal bipyramids, an edgeedge with one MgO5 trigonal bipyramid, and edges with two equivalent NiO5 trigonal bipyramids. There are a spread of Ni–O bond distances ranging from 1.95–2.23 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to one Mg2+ and three Ni2+ atoms to form distorted OMgNi3 tetrahedra that share corners with two equivalent OMgNi3 tetrahedra, corners with eight OMg2Ni3 trigonal bipyramids, and an edgeedge with one OMg3Ni2 trigonal bipyramid. In the second O2- site, O2- is bonded to two equivalent Mg2+ and three Ni2+ atoms to form distorted OMg2Ni3 trigonal bipyramids that share corners with four OMgNi3 tetrahedra and edges with four OMg2Ni3 trigonal bipyramids. In the third O2- site, O2- is bonded to two equivalent Mg2+ and three Ni2+ atoms to form distorted OMg2Ni3 trigonal bipyramids that share corners with four OMgNi3 tetrahedra and edges with four OMg2Ni3 trigonal bipyramids. In the fourth O2- site, O2- is bonded to one Mg2+ and three Ni2+ atoms to form distorted OMgNi3 tetrahedra that share corners with two equivalent OMgNi3 tetrahedra, corners with eight OMg2Ni3 trigonal bipyramids, and an edgeedge with one OMg3Ni2 trigonal bipyramid. In the fifth O2- site, O2- is bonded to three Mg2+ and two equivalent Ni2+ atoms to form distorted OMg3Ni2 trigonal bipyramids that share corners with four OMgNi3 tetrahedra, an edgeedge with one OMgNi3 tetrahedra, and edges with four OMg2Ni3 trigonal bipyramids. In the sixth O2- site, O2- is bonded in a 5-coordinate geometry to three Mg2+ and two equivalent Ni2+ atoms. In the seventh O2- site, O2- is bonded to three Mg2+ and two equivalent Ni2+ atoms to form distorted OMg3Ni2 trigonal bipyramids that share corners with four OMgNi3 tetrahedra, an edgeedge with one OMgNi3 tetrahedra, and edges with four OMg2Ni3 trigonal bipyramids. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to three Mg2+ and two equivalent Ni2+ atoms.