Materials Data on FeNiAs by Materials Project

Abstract

FeNiAs crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are two inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded to five As3- atoms to form distorted FeAs5 trigonal bipyramids that share corners with ten equivalent FeAs5 square pyramids, corners with six NiAs4 tetrahedra, edges with four equivalent FeAs5 square pyramids, edges with six NiAs4 tetrahedra, and edges with two equivalent FeAs5 trigonal bipyramids. There are one shorter (2.41 Å) and four longer (2.51 Å) Fe–As bond lengths. In the second Fe2+ site, Fe2+ is bonded to five As3- atoms to form distorted FeAs5 square pyramids that share corners with five equivalent FeAs5 square pyramids, corners with six NiAs4 tetrahedra, corners with five equivalent FeAs5 trigonal bipyramids, edges with four equivalent FeAs5 square pyramids, edges with six NiAs4 tetrahedra, and edges with two equivalent FeAs5 trigonal bipyramids. There are a spread of Fe–As bond distances ranging from 2.46–2.59 Å. There are two inequivalent Ni1+ sites. In the first Ni1+ site, Ni1+ is bonded to four As3- atoms to form NiAs4 tetrahedra that share corners with four equivalent FeAs5 square pyramids, corners with ten NiAs4 tetrahedra, corners with two equivalent FeAs5 trigonal bipyramids, edges with four equivalent FeAs5 square pyramids, edges with two equivalent NiAs4 tetrahedra, and edges with two equivalent FeAs5 trigonal bipyramids. There are two shorter (2.28 Å) and two longer (2.36 Å) Ni–As bond lengths. In the second Ni1+ site, Ni1+ is bonded to four As3- atoms to form NiAs4 tetrahedra that share corners with four equivalent FeAs5 square pyramids, corners with ten NiAs4 tetrahedra, corners with two equivalent FeAs5 trigonal bipyramids, edges with four equivalent FeAs5 square pyramids, edges with two NiAs4 tetrahedra, and edges with two equivalent FeAs5 trigonal bipyramids. There are two shorter (2.29 Å) and two longer (2.35 Å) Ni–As bond lengths. There are two inequivalent As3- sites. In the first As3- site, As3- is bonded in a 9-coordinate geometry to six Fe2+ and three Ni1+ atoms. In the second As3- site, As3- is bonded in a 9-coordinate geometry to three Fe2+ and six Ni1+ atoms.