Materials Data on Mg2Mo3O8 by Materials Project
Mg2Mo3O8 crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six equivalent MoO6 octahedra, corners with three equivalent MgO4 tetrahedra, and edges with three equivalent MoO6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are three shorter (2.12 Å) and three longer (2.18 Å) Mg–O bond lengths. In the second Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with three equivalent MgO6 octahedra and corners with nine equivalent MoO6 octahedra. The corner-sharing octahedra tilt angles range from 54–65°. There are one shorter (2.00 Å) and three longer (2.07 Å) Mg–O bond lengths. Mo4+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with three equivalent MgO4 tetrahedra, an edgeedge with one MgO6 octahedra, and edges with four equivalent MoO6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are a spread of Mo–O bond distances ranging from 2.03–2.16 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+ and two equivalent Mo4+ atoms. In the second O2- site, O2- is bonded to two Mg2+ and two equivalent Mo4+ atoms to form distorted OMg2Mo2 tetrahedra that share corners with two equivalent OMg2Mo2 tetrahedra, a cornercorner with one OMgMo3 trigonal pyramid, edges with two equivalent OMg2Mo2 tetrahedra, and an edgeedge with one OMgMo3 trigonal pyramid. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to three equivalent Mo4+ atoms. In the fourth O2- site, O2- is bonded to one Mg2+ and three equivalent Mo4+ atoms to form a mixture of distorted edge and corner-sharing OMgMo3 trigonal pyramids.