Materials Data on NaAl3Cr2O14 by Materials Project

Abstract

NaCr2Al3O14 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Na is bonded to twelve O atoms to form NaO12 cuboctahedra that share corners with six equivalent CrO4 tetrahedra and faces with six equivalent AlO6 octahedra. There are six shorter (2.70 Å) and six longer (2.87 Å) Na–O bond lengths. Cr is bonded to four O atoms to form CrO4 tetrahedra that share corners with three equivalent NaO12 cuboctahedra and corners with three equivalent AlO6 octahedra. The corner-sharing octahedral tilt angles are 55°. There is one shorter (1.60 Å) and three longer (1.70 Å) Cr–O bond length. Al is bonded to six O atoms to form AlO6 octahedra that share corners with four equivalent AlO6 octahedra, corners with two equivalent CrO4 tetrahedra, and faces with two equivalent NaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 35°. There is four shorter (1.85 Å) and two longer (1.97 Å) Al–O bond length. There are three inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Cr atom. In the second O site, O is bonded in a 2-coordinate geometry to one Na, one Cr, and one Al atom. In the third O site, O is bonded in a bent 150 degrees geometry to one Na and two equivalent Al atoms.