Materials Data on Na2AlCr(P2O7)2 by Materials Project
Na2CrAl(P2O7)2 crystallizes in the monoclinic P2_1 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 2.32–2.64 Å. In the second Na1+ site, Na1+ is bonded in a 7-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.37–3.04 Å. Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Cr–O bond distances ranging from 1.97–2.08 Å. Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.87–1.97 Å. There are four 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 AlO6 octahedra, corners with two equivalent CrO6 octahedra, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 22–52°. There are a spread of P–O bond distances ranging from 1.51–1.62 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CrO6 octahedra, corners with two equivalent AlO6 octahedra, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 17–48°. There are a spread of P–O bond distances ranging from 1.51–1.63 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one AlO6 octahedra, corners with two equivalent CrO6 octahedra, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 34–55°. There are a spread of P–O bond distances ranging from 1.52–1.63 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one CrO6 octahedra, corners with two equivalent AlO6 octahedra, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 31–53°. There are a spread of P–O bond distances ranging from 1.52–1.63 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Cr3+, and one P5+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Al3+, and one P5+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+ and two P5+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+ and two P5+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cr3+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted linear geometry to one Na1+, one Al3+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Al3+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Cr3+, and one P5+ atom. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Al3+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Cr3+, and one P5+ atom. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one Cr3+, and one P5+ atom. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Al3+, and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+, one Cr3+, and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Al3+, and one P5+ atom.