Materials Data on KFe3As4(HO8)2 by Materials Project
KFe3As4(HO8)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.78–3.22 Å. There are two inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four equivalent FeO6 octahedra and corners with six AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–54°. There are a spread of Fe–O bond distances ranging from 1.97–2.12 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with four AsO4 tetrahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–54°. There are a spread of Fe–O bond distances ranging from 1.97–2.12 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 three FeO6 octahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of As–O bond distances ranging from 1.70–1.76 Å. In the second As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with four FeO6 octahedra and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 44–57°. There are a spread of As–O bond distances ranging from 1.69–1.77 Å. H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two Fe3+ and one As5+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two Fe3+ and one As5+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Fe3+, and one As5+ atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one Fe3+ and one As5+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to one K1+, one Fe3+, and one As5+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one As5+, and one H1+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one K1+, one Fe3+, and one As5+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Fe3+ and one As5+ atom.