DOI: 10.17188/1204614
title: Materials Data on Ba4Ga2O7 by Materials Project

description: Ba4Ga2O7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are six inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ba–O bond distances ranging from 2.63–3.06 Å. In the second Ba2+ site, Ba2+ is bonded to seven O2- atoms to form distorted BaO7 pentagonal bipyramids that share corners with four GaO4 tetrahedra, edges with two GaO4 tetrahedra, and faces with two equivalent BaO7 pentagonal bipyramids. There are a spread of Ba–O bond distances ranging from 2.63–2.88 Å. In the third Ba2+ site, Ba2+ is bonded to six O2- atoms to form distorted BaO6 pentagonal pyramids that share a cornercorner with one BaO6 pentagonal pyramid, corners with three GaO4 tetrahedra, edges with two equivalent BaO6 pentagonal pyramids, and edges with two equivalent GaO4 tetrahedra. There are a spread of Ba–O bond distances ranging from 2.65–2.86 Å. In the fourth Ba2+ site, Ba2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ba–O bond distances ranging from 2.76–3.06 Å. In the fifth Ba2+ site, Ba2+ is bonded in a 5-coordinate geometry to seven O2- atoms. There are a spread of Ba–O bond distances ranging from 2.68–3.30 Å. In the sixth Ba2+ site, Ba2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ba–O bond distances ranging from 2.75–3.29 Å. There are three inequivalent Ga3+ sites. In the first Ga3+ site, Ga3+ is bonded to four O2- atoms to form GaO4 tetrahedra that share a cornercorner with one BaO7 pentagonal bipyramid, a cornercorner with one BaO6 pentagonal pyramid, a cornercorner with one GaO4 tetrahedra, and an edgeedge with one BaO7 pentagonal bipyramid. There are a spread of Ga–O bond distances ranging from 1.84–1.98 Å. In the second Ga3+ site, Ga3+ is bonded to four O2- atoms to form GaO4 tetrahedra that share corners with two equivalent BaO6 pentagonal pyramids, a cornercorner with one GaO4 tetrahedra, and edges with two equivalent BaO6 pentagonal pyramids. There are a spread of Ga–O bond distances ranging from 1.84–1.94 Å. In the third Ga3+ site, Ga3+ is bonded to four O2- atoms to form GaO4 tetrahedra that share corners with three equivalent BaO7 pentagonal bipyramids, a cornercorner with one GaO4 tetrahedra, and an edgeedge with one BaO7 pentagonal bipyramid. There are a spread of Ga–O bond distances ranging from 1.84–1.94 Å. There are eleven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to five Ba2+ and one Ga3+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to four Ba2+ and two equivalent Ga3+ atoms. In the third O2- site, O2- is bonded in a 1-coordinate geometry to five Ba2+ and one Ga3+ atom. In the fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Ba2+ and one Ga3+ atom. In the fifth O2- site, O2- is bonded to four Ba2+ and one Ga3+ atom to form a mixture of distorted edge and corner-sharing OBa4Ga square pyramids. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to four Ba2+ and one Ga3+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to five Ba2+ and one Ga3+ atom. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to four Ba2+ and one Ga3+ atom. In the ninth O2- site, O2- is bonded to three Ba2+ and one Ga3+ atom to form distorted corner-sharing OBa3Ga trigonal pyramids. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to four Ba2+ and one Ga3+ atom. In the eleventh O2- site, O2- is bonded in a 2-coordinate geometry to three Ba2+ and two Ga3+ atoms.