DOI: 10.17188/1675663
title: Materials Data on BaMg6NiO8 by Materials Project

description: BaMg6NiO8 is Caswellsilverite-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Ba2+ is bonded to six O2- atoms to form BaO6 octahedra that share corners with two equivalent NiO6 octahedra, corners with four equivalent BaO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.35 Å) and two longer (2.47 Å) Ba–O bond lengths. There are three inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with four equivalent NiO6 octahedra, and edges with eight equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.14 Å) and four longer (2.35 Å) Mg–O bond lengths. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with four equivalent BaO6 octahedra, and edges with eight equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.17 Å) and four longer (2.35 Å) Mg–O bond lengths. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six equivalent MgO6 octahedra, edges with two equivalent BaO6 octahedra, edges with two equivalent NiO6 octahedra, and edges with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–8°. There are a spread of Mg–O bond distances ranging from 2.00–2.35 Å. Ni2+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with two equivalent BaO6 octahedra, corners with four equivalent NiO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (1.84 Å) and four longer (2.35 Å) Ni–O bond lengths. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded to one Ba2+, four equivalent Mg2+, and one Ni2+ atom to form OBaMg4Ni octahedra that share corners with six equivalent OBaMg4Ni octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–8°. In the second O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six equivalent OMg6 octahedra and edges with twelve OBaMg4Ni octahedra. The corner-sharing octahedra tilt angles range from 0–7°. In the third O2- site, O2- is bonded to four Mg2+ and two equivalent Ni2+ atoms to form OMg4Ni2 octahedra that share corners with six OMg4Ni2 octahedra and edges with twelve OBaMg4Ni octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourth O2- site, O2- is bonded to two equivalent Ba2+ and four Mg2+ atoms to form OBa2Mg4 octahedra that share corners with six OMg4Ni2 octahedra and edges with twelve OBaMg4Ni octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifth O2- site, O2- is bonded to four Mg2+ and two equivalent Ni2+ atoms to form OMg4Ni2 octahedra that share corners with six OMg4Ni2 octahedra and edges with twelve OBaMg4Ni octahedra. The corner-sharing octahedral tilt angles are 0°. Both O–Mg bond lengths are 2.00 Å. In the sixth O2- site, O2- is bonded to two equivalent Ba2+ and four Mg2+ atoms to form OBa2Mg4 octahedra that share corners with six OMg4Ni2 octahedra and edges with twelve OBaMg4Ni octahedra. The corner-sharing octahedral tilt angles are 0°. Both O–Mg bond lengths are 2.31 Å.