DOI: 10.17188/1271756
title: Materials Data on NaMg4(PO4)3 by Materials Project

description: NaMg4(PO4)3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Na1+ is bonded to six O2- atoms to form distorted NaO6 pentagonal pyramids that share corners with two equivalent MgO5 square pyramids, corners with two equivalent PO4 tetrahedra, corners with two equivalent MgO5 trigonal bipyramids, and edges with two PO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.52–2.73 Å. There are three inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to five O2- atoms to form distorted MgO5 square pyramids that share a cornercorner with one NaO6 pentagonal pyramid, corners with five PO4 tetrahedra, a cornercorner with one MgO5 trigonal bipyramid, and edges with two equivalent MgO5 square pyramids. There are a spread of Mg–O bond distances ranging from 1.99–2.15 Å. In the second Mg2+ site, Mg2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mg–O bond distances ranging from 1.98–2.63 Å. In the third Mg2+ site, Mg2+ is bonded to five O2- atoms to form distorted MgO5 trigonal bipyramids that share corners with two equivalent NaO6 pentagonal pyramids, corners with two equivalent MgO5 square pyramids, and corners with five PO4 tetrahedra. There are a spread of Mg–O bond distances ranging from 1.99–2.20 Å. There are three inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent NaO6 pentagonal pyramids, corners with two equivalent MgO5 square pyramids, and corners with two equivalent MgO5 trigonal bipyramids. There is three shorter (1.55 Å) and one longer (1.57 Å) P–O bond length. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four equivalent MgO5 square pyramids, corners with three equivalent MgO5 trigonal bipyramids, and an edgeedge with one NaO6 pentagonal pyramid. There are a spread of P–O bond distances ranging from 1.52–1.60 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four equivalent MgO5 square pyramids and an edgeedge with one NaO6 pentagonal pyramid. There are a spread of P–O bond distances ranging from 1.52–1.60 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Na1+, one Mg2+, and one P5+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one Mg2+, and one P5+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Mg2+ and one P5+ atom. In the fourth O2- site, O2- is bonded to three Mg2+ and one P5+ atom to form edge-sharing OMg3P tetrahedra. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to two Mg2+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Mg2+, and one P5+ atom. In the seventh O2- site, O2- is bonded to three Mg2+ and one P5+ atom to form edge-sharing OMg3P tetrahedra. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to three Mg2+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to two Mg2+ and one P5+ atom.