DOI: 10.17188/1675970
title: Materials Data on BaMg6NbO8 by Materials Project

description: BaMg6NbO8 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 MgO6 octahedra, corners with four equivalent BaO6 octahedra, edges with four equivalent NbO6 octahedra, and edges with eight equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.34 Å) and two longer (2.54 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 two equivalent BaO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (1.94 Å) and four longer (2.34 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 two equivalent NbO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.13 Å) and four longer (2.34 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 NbO6 octahedra, and edges with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. There are a spread of Mg–O bond distances ranging from 2.06–2.43 Å. Nb2+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent NbO6 octahedra, edges with four equivalent BaO6 octahedra, and edges with eight equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.34 Å) and two longer (2.36 Å) Nb–O bond lengths. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded to one Ba2+ and five Mg2+ atoms to form OBaMg5 octahedra that share corners with six equivalent OBaMg5 octahedra and edges with twelve OMg5Nb octahedra. The corner-sharing octahedra tilt angles range from 0–6°. In the second O2- site, O2- is bonded to five Mg2+ and one Nb2+ atom to form OMg5Nb octahedra that share corners with six equivalent OMg5Nb octahedra and edges with twelve OBaMg5 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. In the third O2- site, O2- is bonded to two equivalent Ba2+, two equivalent Mg2+, and two equivalent Nb2+ atoms to form OBa2Mg2Nb2 octahedra that share corners with six OBa2Mg2Nb2 octahedra and edges with twelve OBaMg5 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OBa2Mg2Nb2 octahedra and edges with twelve OBaMg5 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifth O2- site, O2- is bonded to two equivalent Ba2+, two equivalent Mg2+, and two equivalent Nb2+ atoms to form OBa2Mg2Nb2 octahedra that share corners with six OBa2Mg2Nb2 octahedra and edges with twelve OBaMg5 octahedra. The corner-sharing octahedral tilt angles are 0°. Both O–Mg bond lengths are 2.43 Å. In the sixth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OBa2Mg2Nb2 octahedra and edges with twelve OBaMg5 octahedra. The corner-sharing octahedral tilt angles are 0°. Both O–Mg bond lengths are 2.06 Å.