Materials Data on Ni2As2O9 by Materials Project
Ni2As2O9 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Ni4+ sites. In the first Ni4+ site, Ni4+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with five AsO4 tetrahedra and edges with two equivalent NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.87–2.11 Å. In the second Ni4+ site, Ni4+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with five AsO4 tetrahedra and edges with two equivalent NiO6 octahedra. There are a spread of Ni–O bond distances ranging from 1.86–2.13 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 five NiO6 octahedra and a cornercorner with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–62°. There are a spread of As–O bond distances ranging from 1.69–1.79 Å. In the second As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with five NiO6 octahedra and a cornercorner with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–62°. There are a spread of As–O bond distances ranging from 1.67–1.80 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to one Ni4+ and one As5+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ni4+ and one As5+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ni4+ and one As5+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one Ni4+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ni4+ and one As5+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to one Ni4+ atom. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to one Ni4+ and one As5+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ni4+ and one As5+ atom. In the ninth O2- site, O2- is bonded in a bent 120 degrees geometry to two As5+ atoms.