Materials Data on Mn3Nb2O9 by Materials Project
Nb2Mn3O9 crystallizes in the trigonal P3c1 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 six MnO6 octahedra and corners with three equivalent MnO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 33–44°. There are three shorter (1.88 Å) and three longer (2.24 Å) Nb–O bond lengths. In the second Nb5+ site, Nb5+ is bonded in a 6-coordinate geometry to six O2- atoms. There are three shorter (1.98 Å) and three longer (2.08 Å) Nb–O bond lengths. There are three inequivalent Mn+2.67+ sites. In the first Mn+2.67+ site, Mn+2.67+ is bonded to six O2- atoms to form distorted MnO6 octahedra that share corners with three equivalent NbO6 octahedra, corners with three equivalent MnO6 octahedra, and a faceface with one MnO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 33–45°. There is three shorter (1.90 Å) and three longer (2.08 Å) Mn–O bond length. In the second Mn+2.67+ site, Mn+2.67+ is bonded to six O2- atoms to form distorted MnO6 pentagonal pyramids that share corners with three equivalent NbO6 octahedra, edges with three equivalent MnO6 octahedra, and a faceface with one MnO6 octahedra. The corner-sharing octahedral tilt angles are 55°. There are three shorter (2.07 Å) and three longer (2.30 Å) Mn–O bond lengths. In the third Mn+2.67+ site, Mn+2.67+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with three equivalent NbO6 octahedra, corners with three equivalent MnO6 octahedra, and edges with three equivalent MnO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 44–45°. There are three shorter (2.14 Å) and three longer (2.25 Å) Mn–O bond lengths. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to one Nb5+ and three Mn+2.67+ atoms to form a mixture of distorted edge and corner-sharing OMn3Nb trigonal pyramids. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Nb5+ and two Mn+2.67+ atoms. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to two Nb5+ and one Mn+2.67+ atom.