DOI: 10.17188/1192445
title: Materials Data on Mg3BeAl8O16 by Materials Project

description: BeMg3Al8O16 is Spinel-derived structured and crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. there are three inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 octahedra that share corners with six equivalent AlO6 octahedra, corners with three equivalent BeO4 tetrahedra, corners with three equivalent AlO4 tetrahedra, and edges with three equivalent AlO6 octahedra. The corner-sharing octahedral tilt angles are 56°. There are three shorter (2.04 Å) and three longer (2.22 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 twelve AlO6 octahedra. The corner-sharing octahedral tilt angles are 60°. There is three shorter (1.96 Å) and one longer (2.00 Å) Mg–O bond length. In the third Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with twelve AlO6 octahedra. The corner-sharing octahedra tilt angles range from 58–60°. All Mg–O bond lengths are 1.95 Å. Be2+ is bonded to four O2- atoms to form BeO4 tetrahedra that share corners with three equivalent MgO6 octahedra, corners with three equivalent AlO6 octahedra, and edges with three equivalent AlO6 octahedra. The corner-sharing octahedra tilt angles range from 54–58°. There is one shorter (1.61 Å) and three longer (1.68 Å) Be–O bond length. There are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent MgO6 octahedra, a cornercorner with one AlO4 tetrahedra, corners with three MgO4 tetrahedra, edges with five AlO6 octahedra, and an edgeedge with one BeO4 tetrahedra. The corner-sharing octahedral tilt angles are 56°. There are a spread of Al–O bond distances ranging from 1.91–1.99 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share a cornercorner with one BeO4 tetrahedra, corners with two equivalent AlO4 tetrahedra, corners with three MgO4 tetrahedra, an edgeedge with one MgO6 octahedra, and edges with five AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.92–1.95 Å. In the third Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with three equivalent MgO6 octahedra and corners with nine AlO6 octahedra. The corner-sharing octahedra tilt angles range from 56–63°. All Al–O bond lengths are 1.81 Å. In the fourth Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with six MgO4 tetrahedra and edges with six AlO6 octahedra. There is three shorter (1.92 Å) and three longer (1.93 Å) Al–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+, one Be2+, and two equivalent Al3+ atoms. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Al3+ atoms. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Al3+ atoms. In the fourth O2- site, O2- is bonded to one Mg2+ and three equivalent Al3+ atoms to form distorted OMgAl3 tetrahedra that share corners with nine OMgAl3 tetrahedra and corners with three equivalent OBeAl3 trigonal pyramids. In the fifth O2- site, O2- is bonded to one Mg2+ and three Al3+ atoms to form distorted OMgAl3 tetrahedra that share corners with seven OMgAl3 tetrahedra, a cornercorner with one OMgAl3 trigonal pyramid, edges with two equivalent OMgAl3 tetrahedra, and an edgeedge with one OBeAl3 trigonal pyramid. In the sixth O2- site, O2- is bonded to one Be2+ and three equivalent Al3+ atoms to form a mixture of distorted edge and corner-sharing OBeAl3 trigonal pyramids. In the seventh O2- site, O2- is bonded to one Mg2+ and three Al3+ atoms to form a mixture of distorted edge and corner-sharing OMgAl3 tetrahedra. In the eighth O2- site, O2- is bonded to one Mg2+ and three equivalent Al3+ atoms to form distorted corner-sharing OMgAl3 trigonal pyramids.