DOI: 10.17188/1672043
title: Materials Data on BaSrMg6O8 by Materials Project

description: BaSrMg6O8 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 SrO6 octahedra, and edges with eight equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.40 Å) and two longer (2.59 Å) Ba–O bond lengths. Sr2+ is bonded to six O2- atoms to form SrO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent SrO6 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 (2.40 Å) and two longer (2.52 Å) Sr–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 SrO6 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 (2.03 Å) and four longer (2.40 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 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 (1.96 Å) and four longer (2.40 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 SrO6 octahedra, and edges with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Mg–O bond distances ranging from 2.02–2.53 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded to one Sr2+ and five Mg2+ atoms to form OSrMg5 octahedra that share corners with six equivalent OSrMg5 octahedra and edges with twelve OBaMg5 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the second 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 OSrMg5 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 Sr2+, and two equivalent Mg2+ atoms to form OBa2Sr2Mg2 octahedra that share corners with six OBa2Sr2Mg2 octahedra and edges with twelve OSrMg5 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 OBa2Sr2Mg2 octahedra and edges with twelve OSrMg5 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifth O2- site, O2- is bonded to two equivalent Ba2+, two equivalent Sr2+, and two equivalent Mg2+ atoms to form OBa2Sr2Mg2 octahedra that share corners with six OBa2Sr2Mg2 octahedra and edges with twelve OSrMg5 octahedra. The corner-sharing octahedral tilt angles are 0°. Both O–Mg bond lengths are 2.53 Å. In the sixth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OBa2Sr2Mg2 octahedra and edges with twelve OSrMg5 octahedra. The corner-sharing octahedral tilt angles are 0°. Both O–Mg bond lengths are 2.02 Å.