Materials Data on Na2FePCO7 by Materials Project

Abstract

Na2FeCPO7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.39–2.79 Å. In the second Na1+ site, Na1+ is bonded to seven O2- atoms to form distorted NaO7 pentagonal bipyramids that share a cornercorner with one FeO6 octahedra, corners with two equivalent PO4 tetrahedra, an edgeedge with one FeO6 octahedra, an edgeedge with one PO4 tetrahedra, and a faceface with one FeO6 octahedra. The corner-sharing octahedral tilt angles are 65°. There are a spread of Na–O bond distances ranging from 2.25–2.72 Å. Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one NaO7 pentagonal bipyramid, corners with four equivalent PO4 tetrahedra, an edgeedge with one NaO7 pentagonal bipyramid, and a faceface with one NaO7 pentagonal bipyramid. There are a spread of Fe–O bond distances ranging from 1.97–2.14 Å. C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.27–1.32 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four equivalent FeO6 octahedra, corners with two equivalent NaO7 pentagonal bipyramids, and an edgeedge with one NaO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 34–43°. There is two shorter (1.55 Å) and two longer (1.56 Å) P–O bond length. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Fe3+, and one P5+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to three Na1+ and one C4+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+, one Fe3+, and one C4+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+, one Fe3+, and one C4+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one Fe3+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one Fe3+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Fe3+, and one P5+ atom.