Materials Data on K2U2O7 by Materials Project
K2U2O7 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to six O2- atoms to form KO6 octahedra that share corners with six UO6 octahedra and edges with six KO6 octahedra. The corner-sharing octahedra tilt angles range from 54–59°. There are a spread of K–O bond distances ranging from 2.71–2.83 Å. In the second K1+ site, K1+ is bonded to six O2- atoms to form distorted KO6 octahedra that share corners with six UO6 octahedra and edges with six KO6 octahedra. The corner-sharing octahedra tilt angles range from 53–59°. There are a spread of K–O bond distances ranging from 2.71–2.86 Å. There are two inequivalent U6+ sites. In the first U6+ site, U6+ is bonded to six O2- atoms to form UO6 octahedra that share corners with five UO6 octahedra, corners with six KO6 octahedra, and an edgeedge with one UO6 octahedra. The corner-sharing octahedra tilt angles range from 9–59°. There are a spread of U–O bond distances ranging from 1.88–2.32 Å. In the second U6+ site, U6+ is bonded to six O2- atoms to form UO6 octahedra that share corners with five UO6 octahedra, corners with six KO6 octahedra, and an edgeedge with one UO6 octahedra. The corner-sharing octahedra tilt angles range from 9–59°. There are a spread of U–O bond distances ranging from 1.89–2.28 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two U6+ atoms. In the second O2- site, O2- is bonded in a 1-coordinate geometry to three K1+ and one U6+ atom. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three K1+ and one U6+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to three K1+ and one U6+ atom. In the fifth O2- site, O2- is bonded in a trigonal planar geometry to three U6+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to three U6+ atoms. In the seventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three K1+ and one U6+ atom.