DOE OSTI2020
Ca3Mn2(GaO5)2 crystallizes in the monoclinic Pc space group. The structure is three-dimensional. there are three inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.25–2.98 Å. In the second Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.24–2.49 Å. In the third Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.35–2.96 Å. There are two inequivalent Mn4+ sites. In the first Mn4+ site, Mn4+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with four equivalent MnO6 octahedra and corners with two GaO4 tetrahedra. The corner-sharing octahedra tilt angles range from 6–23°. There are a spread of Mn–O bond distances ranging from 1.88–2.06 Å. In the second Mn4+ site, Mn4+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with four equivalent MnO6 octahedra and corners with two GaO4 tetrahedra. The corner-sharing octahedra tilt angles range from 6–23°. There are a spread of Mn–O bond distances ranging from 1.88–2.12 Å. There are two inequivalent Ga3+ sites. In the first Ga3+ site, Ga3+ is bonded to four O2- atoms to form GaO4 tetrahedra that share corners with two MnO6 octahedra and corners with two equivalent GaO4 tetrahedra. The corner-sharing octahedra tilt angles range from 42–45°. There are a spread of Ga–O bond distances ranging from 1.83–1.90 Å. In the second Ga3+ site, Ga3+ is bonded to four O2- atoms to form GaO4 tetrahedra that share corners with two MnO6 octahedra and corners with two equivalent GaO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–45°. There are a spread of Ga–O bond distances ranging from 1.83–1.90 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+, one Mn4+, and one Ga3+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Mn4+, and one Ga3+ atom. In the third O2- site, O2- is bonded in a trigonal non-coplanar geometry to one Ca2+ and two Ga3+ atoms. In the fourth O2- site, O2- is bonded to three Ca2+ and two Mn4+ atoms to form distorted OCa3Mn2 square pyramids that share corners with two equivalent OCa2Ga2 tetrahedra, an edgeedge with one OCa3Mn2 square pyramid, and a faceface with one OCa3Mn2 square pyramid. In the fifth O2- site, O2- is bonded to two Ca2+ and two Ga3+ atoms to form distorted corner-sharing OCa2Ga2 tetrahedra. In the sixth O2- site, O2- is bonded in a 5-coordinate geometry to three Ca2+ and two Mn4+ atoms. In the seventh O2- site, O2- is bonded to three Ca2+ and two Mn4+ atoms to form distorted OCa3Mn2 square pyramids that share corners with two equivalent OCa2Ga2 tetrahedra, an edgeedge with one OCa3Mn2 square pyramid, and a faceface with one OCa3Mn2 square pyramid. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to three Ca2+ and two Mn4+ atoms. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ca2+, one Mn4+, and one Ga3+ atom. In the tenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Mn4+, and one Ga3+ atom.