DOE OSTI2014
MgMnO2 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 four MgO4 tetrahedra, corners with six MnO5 trigonal bipyramids, an edgeedge with one MnO5 trigonal bipyramid, edges with two equivalent MgO5 trigonal bipyramids, and a faceface with one MnO5 trigonal bipyramid. There are a spread of Mg–O bond distances ranging from 2.04–2.18 Å. In the second Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 trigonal bipyramids that share corners with four MgO4 tetrahedra, corners with six MnO5 trigonal bipyramids, an edgeedge with one MnO5 trigonal bipyramid, edges with two equivalent MgO5 trigonal bipyramids, and a faceface with one MnO5 trigonal bipyramid. There are a spread of Mg–O bond distances ranging from 2.04–2.17 Å. In the third Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with two equivalent MgO4 tetrahedra, corners with four MgO5 trigonal bipyramids, corners with four MnO5 trigonal bipyramids, and edges with three MnO5 trigonal bipyramids. There are a spread of Mg–O bond distances ranging from 1.94–2.03 Å. In the fourth Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with two equivalent MgO4 tetrahedra, corners with four MgO5 trigonal bipyramids, corners with four MnO5 trigonal bipyramids, and edges with three MnO5 trigonal bipyramids. There are a spread of Mg–O bond distances ranging from 1.94–2.03 Å. There are four inequivalent Mn2+ sites. In the first Mn2+ site, Mn2+ is bonded to five O2- atoms to form distorted MnO5 trigonal bipyramids that share corners with four MgO5 trigonal bipyramids, corners with four MnO5 trigonal bipyramids, edges with two equivalent MgO4 tetrahedra, an edgeedge with one MgO5 trigonal bipyramid, and edges with two equivalent MnO5 trigonal bipyramids. There are a spread of Mn–O bond distances ranging from 2.05–2.33 Å. In the second Mn2+ site, Mn2+ is bonded to five O2- atoms to form distorted MnO5 trigonal bipyramids that share corners with four MgO4 tetrahedra, corners with two equivalent MgO5 trigonal bipyramids, corners with four MnO5 trigonal bipyramids, an edgeedge with one MgO4 tetrahedra, edges with two equivalent MnO5 trigonal bipyramids, and a faceface with one MgO5 trigonal bipyramid. There are a spread of Mn–O bond distances ranging from 2.07–2.33 Å. In the third Mn2+ site, Mn2+ is bonded to five O2- atoms to form distorted MnO5 trigonal bipyramids that share corners with four MgO4 tetrahedra, corners with two equivalent MgO5 trigonal bipyramids, corners with four MnO5 trigonal bipyramids, an edgeedge with one MgO4 tetrahedra, edges with two equivalent MnO5 trigonal bipyramids, and a faceface with one MgO5 trigonal bipyramid. There are a spread of Mn–O bond distances ranging from 2.08–2.31 Å. In the fourth Mn2+ site, Mn2+ is bonded to five O2- atoms to form distorted MnO5 trigonal bipyramids that share corners with four MgO5 trigonal bipyramids, corners with four MnO5 trigonal bipyramids, edges with two equivalent MgO4 tetrahedra, an edgeedge with one MgO5 trigonal bipyramid, and edges with two equivalent MnO5 trigonal bipyramids. There are a spread of Mn–O bond distances ranging from 2.05–2.36 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to one Mg2+ and three Mn2+ atoms to form distorted OMgMn3 tetrahedra that share corners with two equivalent OMgMn3 tetrahedra, corners with eight OMg2Mn3 trigonal bipyramids, and an edgeedge with one OMg3Mn2 trigonal bipyramid. In the second O2- site, O2- is bonded to two equivalent Mg2+ and three Mn2+ atoms to form distorted OMg2Mn3 trigonal bipyramids that share corners with four OMgMn3 tetrahedra and edges with four OMg2Mn3 trigonal bipyramids. In the third O2- site, O2- is bonded to two equivalent Mg2+ and three Mn2+ atoms to form distorted OMg2Mn3 trigonal bipyramids that share corners with four OMgMn3 tetrahedra and edges with four OMg2Mn3 trigonal bipyramids. In the fourth O2- site, O2- is bonded to one Mg2+ and three Mn2+ atoms to form distorted OMgMn3 tetrahedra that share corners with two equivalent OMgMn3 tetrahedra, corners with eight OMg2Mn3 trigonal bipyramids, and an edgeedge with one OMg3Mn2 trigonal bipyramid. In the fifth O2- site, O2- is bonded to three Mg2+ and two equivalent Mn2+ atoms to form distorted OMg3Mn2 trigonal bipyramids that share corners with four OMgMn3 tetrahedra, an edgeedge with one OMgMn3 tetrahedra, and edges with four OMg2Mn3 trigonal bipyramids. In the sixth O2- site, O2- is bonded in a 5-coordinate geometry to three Mg2+ and two equivalent Mn2+ atoms. In the seventh O2- site, O2- is bonded to three Mg2+ and two equivalent Mn2+ atoms to form distorted OMg3Mn2 trigonal bipyramids that share corners with four OMgMn3 tetrahedra, an edgeedge with one OMgMn3 tetrahedra, and edges with four OMg2Mn3 trigonal bipyramids. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to three Mg2+ and two equivalent Mn2+ atoms.