DOE OSTI2020
Pb4Mn9O20 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are six inequivalent Mn+3.56+ sites. In the first Mn+3.56+ site, Mn+3.56+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MnO6 octahedra. The corner-sharing octahedral tilt angles are 52°. There are a spread of Mn–O bond distances ranging from 1.92–1.99 Å. In the second Mn+3.56+ site, Mn+3.56+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MnO6 octahedra. The corner-sharing octahedra tilt angles range from 53–55°. There are a spread of Mn–O bond distances ranging from 1.93–2.05 Å. In the third Mn+3.56+ site, Mn+3.56+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MnO6 octahedra. The corner-sharing octahedra tilt angles range from 50–55°. There are a spread of Mn–O bond distances ranging from 1.90–2.06 Å. In the fourth Mn+3.56+ site, Mn+3.56+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MnO6 octahedra. The corner-sharing octahedral tilt angles are 10°. There are a spread of Mn–O bond distances ranging from 1.93–1.99 Å. In the fifth Mn+3.56+ site, Mn+3.56+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MnO6 octahedra. The corner-sharing octahedra tilt angles range from 50–53°. There are a spread of Mn–O bond distances ranging from 1.95–2.16 Å. In the sixth Mn+3.56+ site, Mn+3.56+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MnO6 octahedra. The corner-sharing octahedral tilt angles are 10°. There are a spread of Mn–O bond distances ranging from 1.93–2.16 Å. There are three inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Pb–O bond distances ranging from 2.48–3.11 Å. In the second Pb2+ site, Pb2+ is bonded in a 3-coordinate geometry to three O2- atoms. There are one shorter (2.32 Å) and two longer (2.34 Å) Pb–O bond lengths. In the third Pb2+ site, Pb2+ is bonded in a 3-coordinate geometry to three O2- atoms. There are a spread of Pb–O bond distances ranging from 2.30–2.45 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Mn+3.56+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two Mn+3.56+ and two Pb2+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two Mn+3.56+ and one Pb2+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to three Mn+3.56+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two Mn+3.56+ and two Pb2+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three Mn+3.56+ and one Pb2+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to two Mn+3.56+ and two Pb2+ atoms. In the eighth O2- site, O2- is bonded in a distorted tetrahedral geometry to three Mn+3.56+ and one Pb2+ atom. In the ninth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Mn+3.56+ atoms. In the tenth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Mn+3.56+ and one Pb2+ atom. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to three Mn+3.56+ atoms. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to three Mn+3.56+ atoms.