Materials Data on K3UO2F5 by Materials Project

Abstract

K3UO2F5 crystallizes in the tetragonal I4_1/a space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 9-coordinate geometry to two equivalent O2- and seven F1- atoms. There are one shorter (3.04 Å) and one longer (3.11 Å) K–O bond lengths. There are a spread of K–F bond distances ranging from 2.64–3.24 Å. In the second K1+ site, K1+ is bonded to four equivalent O2- and four equivalent F1- atoms to form distorted KO4F4 hexagonal bipyramids that share corners with four equivalent UO2F5 pentagonal bipyramids and edges with two equivalent UO2F5 pentagonal bipyramids. All K–O bond lengths are 2.90 Å. All K–F bond lengths are 2.77 Å. In the third K1+ site, K1+ is bonded to six F1- atoms to form KF6 octahedra that share corners with six equivalent UO2F5 pentagonal bipyramids. There are four shorter (2.60 Å) and two longer (2.68 Å) K–F bond lengths. U6+ is bonded to two equivalent O2- and five F1- atoms to form UO2F5 pentagonal bipyramids that share corners with two equivalent KO4F4 hexagonal bipyramids, corners with three equivalent KF6 octahedra, and an edgeedge with one KO4F4 hexagonal bipyramid. The corner-sharing octahedra tilt angles range from 0–35°. Both U–O bond lengths are 1.85 Å. There are a spread of U–F bond distances ranging from 2.27–2.30 Å. O2- is bonded in a distorted single-bond geometry to three K1+ and one U6+ atom. There are three inequivalent F1- sites. In the first F1- site, F1- is bonded in a 5-coordinate geometry to four K1+ and one U6+ atom. In the second F1- site, F1- is bonded in a 2-coordinate geometry to five K1+ and one U6+ atom. In the third F1- site, F1- is bonded to three K1+ and one U6+ atom to form a mixture of distorted edge and corner-sharing FK3U tetrahedra.