DOE OSTI2020
Ca3Fe2(MoO6)2 crystallizes in the triclinic P1 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 2.35–2.71 Å. In the second 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 2.36–2.61 Å. In the third 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 2.34–2.72 Å. There are two inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 22–31°. There are a spread of Mo–O bond distances ranging from 1.88–2.03 Å. In the second Mo6+ site, Mo6+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 19–32°. There are a spread of Mo–O bond distances ranging from 1.86–2.05 Å. There are two inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 19–32°. There are a spread of Fe–O bond distances ranging from 1.99–2.09 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 22–31°. There are a spread of Fe–O bond distances ranging from 2.00–2.06 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Mo6+, and one Fe3+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Mo6+, and one Fe3+ atom. In the third O2- site, O2- is bonded to two Ca2+, one Mo6+, and one Fe3+ atom to form a mixture of distorted corner and edge-sharing OCa2FeMo trigonal pyramids. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to three Ca2+, one Mo6+, and one Fe3+ atom. In the fifth O2- site, O2- is bonded in a 5-coordinate geometry to three Ca2+, one Mo6+, and one Fe3+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Mo6+, and one Fe3+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Mo6+, and one Fe3+ atom. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Mo6+, and one Fe3+ atom. In the ninth O2- site, O2- is bonded in a distorted T-shaped geometry to one Ca2+, one Mo6+, and one Fe3+ atom. In the tenth O2- site, O2- is bonded in a distorted T-shaped geometry to one Ca2+, one Mo6+, and one Fe3+ atom. In the eleventh O2- site, O2- is bonded to two Ca2+, one Mo6+, and one Fe3+ atom to form distorted corner-sharing OCa2FeMo tetrahedra. In the twelfth O2- site, O2- is bonded to two Ca2+, one Mo6+, and one Fe3+ atom to form a mixture of distorted corner and edge-sharing OCa2FeMo tetrahedra.