Materials Data on Na2VNiF7 by Materials Project

Na2VNiF7 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a distorted body-centered cubic geometry to eight F1- atoms. There are four shorter (2.48 Å) and four longer (2.76 Å) Na–F bond lengths. In the second Na1+ site, Na1+ is bonded to eight F1- atoms to form distorted NaF8 hexagonal bipyramids that share corners with two equivalent NaF8 hexagonal bipyramids, corners with two equivalent VF6 octahedra, edges with two equivalent VF6 octahedra, and edges with four equivalent NiF6 octahedra. The corner-sharing octahedral tilt angles are 54°. There are a spread of Na–F bond distances ranging from 2.24–2.85 Å. V3+ is bonded to six F1- atoms to form VF6 octahedra that share corners with two equivalent NaF8 hexagonal bipyramids, corners with four equivalent NiF6 octahedra, and edges with two equivalent NaF8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 43°. There is four shorter (1.98 Å) and two longer (1.99 Å) V–F bond length. Ni2+ is bonded to six F1- atoms to form NiF6 octahedra that share corners with two equivalent NiF6 octahedra, corners with four equivalent VF6 octahedra, and edges with four equivalent NaF8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 43–45°. There is two shorter (1.98 Å) and four longer (2.01 Å) Ni–F bond length. There are three inequivalent F1- sites. In the first F1- site, F1- is bonded in a 2-coordinate geometry to two equivalent Na1+ and two equivalent Ni2+ atoms. In the second F1- site, F1- is bonded to three Na1+ and one V3+ atom to form a mixture of distorted edge and corner-sharing FNa3V tetrahedra. In the third F1- site, F1- is bonded in a 4-coordinate geometry to two Na1+, one V3+, and one Ni2+ atom.