Materials Data on NaMn4(AsO4)3 by Materials Project
NaMn4(AsO4)3 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Na1+ is bonded in a distorted square co-planar geometry to four equivalent O2- atoms. There are two shorter (2.42 Å) and two longer (2.57 Å) Na–O bond lengths. There are three inequivalent Mn2+ sites. In the first Mn2+ site, Mn2+ is bonded to six O2- atoms to form distorted MnO6 pentagonal pyramids that share corners with six AsO4 tetrahedra and edges with two equivalent MnO6 octahedra. There are a spread of Mn–O bond distances ranging from 2.21–2.33 Å. In the second Mn2+ site, Mn2+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with six AsO4 tetrahedra, an edgeedge with one MnO6 octahedra, and an edgeedge with one MnO6 pentagonal pyramid. There are a spread of Mn–O bond distances ranging from 2.15–2.25 Å. In the third 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 2.17–2.72 Å. There are two inequivalent As5+ sites. In the first As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with four equivalent MnO6 octahedra and corners with two equivalent MnO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 59–63°. There is two shorter (1.72 Å) and two longer (1.75 Å) As–O bond length. In the second As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with four equivalent MnO6 octahedra and corners with two equivalent MnO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 44–60°. There are a spread of As–O bond distances ranging from 1.71–1.76 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to two Mn2+ and one As5+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Mn2+ and one As5+ atom. In the third O2- site, O2- is bonded to two equivalent Na1+, one Mn2+, and one As5+ atom to form a mixture of distorted corner and edge-sharing ONa2MnAs trigonal pyramids. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to three Mn2+ and one As5+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to two Mn2+ and one As5+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two Mn2+ and one As5+ atom.