DOE OSTI2020
Na2MgP4(H2O3)6 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 pentagonal pyramids that share a cornercorner with one NaO6 octahedra, corners with four PO4 tetrahedra, and a faceface with one MgO6 octahedra. The corner-sharing octahedral tilt angles are 71°. There are a spread of Na–O bond distances ranging from 2.34–2.48 Å. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share a cornercorner with one NaO6 pentagonal pyramid, corners with four equivalent PO4 tetrahedra, and an edgeedge with one MgO6 octahedra. There are a spread of Na–O bond distances ranging from 2.37–2.63 Å. Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with four PO4 tetrahedra, an edgeedge with one NaO6 octahedra, and a faceface with one NaO6 pentagonal pyramid. There are a spread of Mg–O bond distances ranging from 2.08–2.16 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one MgO6 octahedra, corners with two equivalent NaO6 octahedra, a cornercorner with one NaO6 pentagonal pyramid, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–52°. There are a spread of P–O bond distances ranging from 1.51–1.63 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one MgO6 octahedra, a cornercorner with one NaO6 pentagonal pyramid, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. There are a spread of P–O bond distances ranging from 1.51–1.63 Å. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.03 Å) and one longer (1.54 Å) H–O bond length. In the second H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.04 Å) and one longer (1.54 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a single-bond geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.70 Å) H–O bond length. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are eleven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one P5+, and one H1+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Mg2+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one P5+, and one H1+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to one P5+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one P5+ and two H1+ atoms. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Mg2+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted water-like geometry to one Na1+, one Mg2+, and two equivalent H1+ atoms. In the ninth O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two equivalent H1+ atoms. In the tenth O2- site, O2- is bonded in a distorted water-like geometry to one Na1+ and two equivalent H1+ atoms. In the eleventh O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Mg2+ and two equivalent H1+ atoms.