DOE OSTI2020
Ba2MgO3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded to seven O2- atoms to form distorted BaO7 pentagonal bipyramids that share corners with four BaO7 pentagonal bipyramids, a cornercorner with one MgO4 tetrahedra, edges with three equivalent BaO7 pentagonal bipyramids, and edges with four MgO4 tetrahedra. There are a spread of Ba–O bond distances ranging from 2.72–3.22 Å. In the second Ba2+ site, Ba2+ is bonded in a 6-coordinate geometry to seven O2- atoms. There are a spread of Ba–O bond distances ranging from 2.66–3.42 Å. In the third Ba2+ site, Ba2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ba–O bond distances ranging from 2.65–3.05 Å. In the fourth Ba2+ site, Ba2+ is bonded to seven O2- atoms to form distorted BaO7 pentagonal bipyramids that share corners with four BaO7 pentagonal bipyramids, a cornercorner with one MgO4 tetrahedra, edges with three equivalent BaO7 pentagonal bipyramids, and edges with four MgO4 tetrahedra. There are a spread of Ba–O bond distances ranging from 2.73–3.26 Å. In the fifth Ba2+ site, Ba2+ is bonded to seven O2- atoms to form distorted BaO7 pentagonal bipyramids that share corners with four BaO7 pentagonal bipyramids, a cornercorner with one MgO4 tetrahedra, edges with three equivalent BaO7 pentagonal bipyramids, and edges with four MgO4 tetrahedra. There are a spread of Ba–O bond distances ranging from 2.72–3.20 Å. In the sixth Ba2+ site, Ba2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ba–O bond distances ranging from 2.66–3.04 Å. In the seventh Ba2+ site, Ba2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ba–O bond distances ranging from 2.66–3.06 Å. In the eighth Ba2+ site, Ba2+ is bonded to seven O2- atoms to form distorted BaO7 pentagonal bipyramids that share corners with four BaO7 pentagonal bipyramids, a cornercorner with one MgO4 tetrahedra, edges with three equivalent BaO7 pentagonal bipyramids, and edges with four MgO4 tetrahedra. There are a spread of Ba–O bond distances ranging from 2.73–3.23 Å. There are four inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share a cornercorner with one BaO7 pentagonal bipyramid, corners with two equivalent MgO4 tetrahedra, and edges with four BaO7 pentagonal bipyramids. There are a spread of Mg–O bond distances ranging from 1.96–2.02 Å. In the second Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share a cornercorner with one BaO7 pentagonal bipyramid, corners with two equivalent MgO4 tetrahedra, and edges with four BaO7 pentagonal bipyramids. There are a spread of Mg–O bond distances ranging from 1.97–2.02 Å. In the third Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share a cornercorner with one BaO7 pentagonal bipyramid, corners with two equivalent MgO4 tetrahedra, and edges with four BaO7 pentagonal bipyramids. There are a spread of Mg–O bond distances ranging from 1.97–2.02 Å. In the fourth Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share a cornercorner with one BaO7 pentagonal bipyramid, corners with two equivalent MgO4 tetrahedra, and edges with four BaO7 pentagonal bipyramids. There are a spread of Mg–O bond distances ranging from 1.97–2.02 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to five Ba2+ and one Mg2+ atom. In the second O2- site, O2- is bonded in a 5-coordinate geometry to four Ba2+ and one Mg2+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to four Ba2+ and two Mg2+ atoms. In the fourth O2- site, O2- is bonded in a distorted linear geometry to four Ba2+ and two Mg2+ atoms. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to five Ba2+ and one Mg2+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to five Ba2+ and one Mg2+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to five Ba2+ and one Mg2+ atom. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to four Ba2+ and one Mg2+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to four Ba2+ and two Mg2+ atoms. In the tenth O2- site, O2- is bonded in a distorted linear geometry to four Ba2+ and two Mg2+ atoms. In the eleventh O2- site, O2- is bonded in a 5-coordinate geometry to four Ba2+ and one Mg2+ atom. In the twelfth O2- site, O2- is bonded in a 6-coordinate geometry to five Ba2+ and one Mg2+ atom.