DOE OSTI2020
KFe(SeO3)2 crystallizes in the orthorhombic Pmn2_1 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.76–2.91 Å. In the second K1+ site, K1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.77–2.90 Å. There are two inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded in an octahedral geometry to six O2- atoms. There are a spread of Fe–O bond distances ranging from 1.99–2.10 Å. In the second Fe3+ site, Fe3+ is bonded in an octahedral geometry to six O2- atoms. There are a spread of Fe–O bond distances ranging from 2.00–2.09 Å. There are four inequivalent Se4+ sites. In the first Se4+ site, Se4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. All Se–O bond lengths are 1.74 Å. In the second Se4+ site, Se4+ is bonded in a distorted trigonal non-coplanar geometry to three O2- atoms. All Se–O bond lengths are 1.74 Å. In the third Se4+ site, Se4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is one shorter (1.72 Å) and two longer (1.73 Å) Se–O bond length. In the fourth Se4+ site, Se4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is one shorter (1.72 Å) and two longer (1.74 Å) Se–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one K1+, one Fe3+, and one Se4+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one K1+, one Fe3+, and one Se4+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one Fe3+ and one Se4+ atom. In the fourth O2- site, O2- is bonded to two K1+, one Fe3+, and one Se4+ atom to form a mixture of distorted edge and corner-sharing OK2FeSe tetrahedra. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+, one Fe3+, and one Se4+ atom. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to one Fe3+ and one Se4+ atom. In the seventh O2- site, O2- is bonded to two K1+, one Fe3+, and one Se4+ atom to form a mixture of distorted edge and corner-sharing OK2FeSe tetrahedra. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+, one Fe3+, and one Se4+ atom.