Materials Data on NaAlAs2O7 by Materials Project
NaAlAs2O7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.30–2.60 Å. Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with six AsO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.90–2.01 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 three equivalent AlO6 octahedra and a cornercorner with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 46–51°. There are a spread of As–O bond distances ranging from 1.70–1.80 Å. In the second As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with three equivalent AlO6 octahedra and a cornercorner with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 41–61°. There are a spread of As–O bond distances ranging from 1.68–1.83 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one As5+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one Al3+, and one As5+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+ and two As5+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one Al3+, and one As5+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one Al3+, and one As5+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one Al3+, and one As5+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Al3+ and one As5+ atom.