Materials Data on BaNi2(AsO4)2 by Materials Project

Abstract

BaNi2(AsO4)2 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with six equivalent NiO6 octahedra, edges with six equivalent BaO12 cuboctahedra, edges with six equivalent AsO4 tetrahedra, and faces with two equivalent NiO6 octahedra. The corner-sharing octahedral tilt angles are 46°. There are six shorter (2.96 Å) and six longer (3.25 Å) Ba–O bond lengths. Ni2+ is bonded to six equivalent O2- atoms to form NiO6 octahedra that share corners with three equivalent BaO12 cuboctahedra, corners with six equivalent AsO4 tetrahedra, edges with three equivalent NiO6 octahedra, and a faceface with one BaO12 cuboctahedra. All Ni–O bond lengths are 2.08 Å. As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with six equivalent NiO6 octahedra and edges with three equivalent BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 54–57°. There is one shorter (1.69 Å) and three longer (1.74 Å) As–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Ba2+, two equivalent Ni2+, and one As5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent Ba2+ and one As5+ atom.