Materials Data on Na3Al(AsO4)2 by Materials Project

Abstract

Na3Al(AsO4)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are three 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 2.36–2.89 Å. In the second Na1+ site, Na1+ is bonded to seven O2- atoms to form distorted NaO7 pentagonal bipyramids that share corners with three equivalent AlO4 tetrahedra, corners with three AsO4 tetrahedra, and edges with two AsO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.39–2.87 Å. In the third 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 2.29–2.80 Å. Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with three equivalent NaO7 pentagonal bipyramids and corners with four AsO4 tetrahedra. There is two shorter (1.78 Å) and two longer (1.79 Å) Al–O bond length. 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 two equivalent NaO7 pentagonal bipyramids, corners with two equivalent AlO4 tetrahedra, and an edgeedge with one NaO7 pentagonal bipyramid. There are a spread of As–O bond distances ranging from 1.69–1.77 Å. In the second As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share a cornercorner with one NaO7 pentagonal bipyramid, corners with two equivalent AlO4 tetrahedra, and an edgeedge with one NaO7 pentagonal bipyramid. There are a spread of As–O bond distances ranging from 1.69–1.77 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Na1+ and one As5+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Na1+, one Al3+, and one As5+ atom. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Na1+ and one As5+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one Al3+, and one As5+ atom. In the fifth O2- site, O2- is bonded in a distorted tetrahedral geometry to three Na1+ and one As5+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Na1+, one Al3+, and one As5+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to three Na1+ and one As5+ atom. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one Al3+, and one As5+ atom.