Materials Data on Mn4Nb2O9 by Materials Project

Mn4Nb2O9 is Ilmenite-like structured and crystallizes in the monoclinic Cc space group. The structure is three-dimensional. there are two inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share corners with three equivalent NbO6 octahedra, corners with three equivalent MnO6 octahedra, corners with three MnO6 pentagonal pyramids, an edgeedge with one MnO6 pentagonal pyramid, and a faceface with one MnO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 39–42°. There are a spread of Nb–O bond distances ranging from 1.90–2.26 Å. In the second Nb5+ site, Nb5+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share corners with three equivalent NbO6 octahedra, corners with three equivalent MnO6 octahedra, corners with two equivalent MnO6 pentagonal pyramids, edges with two equivalent MnO6 pentagonal pyramids, and a faceface with one MnO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 39–47°. There are a spread of Nb–O bond distances ranging from 1.90–2.34 Å. There are four inequivalent Mn2+ sites. In the first Mn2+ site, Mn2+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with six NbO6 octahedra, a cornercorner with one MnO6 pentagonal pyramid, and edges with three MnO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 39–47°. There are a spread of Mn–O bond distances ranging from 2.12–2.29 Å. In the second Mn2+ site, Mn2+ is bonded to six O2- atoms to form distorted MnO6 pentagonal pyramids that share a cornercorner with one MnO6 octahedra, corners with two equivalent NbO6 octahedra, corners with three equivalent MnO6 pentagonal pyramids, an edgeedge with one MnO6 octahedra, edges with two equivalent NbO6 octahedra, and a faceface with one NbO6 octahedra. The corner-sharing octahedra tilt angles range from 57–67°. There are a spread of Mn–O bond distances ranging from 2.11–2.41 Å. In the third Mn2+ site, Mn2+ is bonded to six O2- atoms to form distorted MnO6 pentagonal pyramids that share corners with three NbO6 octahedra, corners with three equivalent MnO6 pentagonal pyramids, an edgeedge with one NbO6 octahedra, edges with two equivalent MnO6 octahedra, and a faceface with one NbO6 octahedra. The corner-sharing octahedra tilt angles range from 59–65°. There are a spread of Mn–O bond distances ranging from 2.16–2.33 Å. In the fourth Mn2+ site, Mn2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mn–O bond distances ranging from 2.14–2.44 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted see-saw-like geometry to two Nb5+ and two Mn2+ atoms. In the second O2- site, O2- is bonded to one Nb5+ and three Mn2+ atoms to form distorted corner-sharing OMn3Nb trigonal pyramids. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two Nb5+ and two Mn2+ atoms. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to one Nb5+ and three Mn2+ atoms. In the fifth O2- site, O2- is bonded to one Nb5+ and three Mn2+ atoms to form distorted corner-sharing OMn3Nb trigonal pyramids. In the sixth O2- site, O2- is bonded in a distorted see-saw-like geometry to one Nb5+ and three Mn2+ atoms. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to two Nb5+ and two Mn2+ atoms. In the eighth O2- site, O2- is bonded in a distorted see-saw-like geometry to one Nb5+ and three Mn2+ atoms. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to one Nb5+ and three Mn2+ atoms.