Materials Data on Cs2U2O5 by Materials Project

Abstract

Cs2U2O5 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are two inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded to eight equivalent O2- atoms to form distorted CsO8 hexagonal bipyramids that share corners with eight equivalent CsO12 cuboctahedra, edges with four equivalent CsO8 hexagonal bipyramids, edges with eight equivalent UO5 square pyramids, and faces with two equivalent CsO12 cuboctahedra. All Cs–O bond lengths are 3.23 Å. In the second Cs1+ site, Cs1+ is bonded to twelve O2- atoms to form CsO12 cuboctahedra that share corners with four equivalent CsO12 cuboctahedra, corners with eight equivalent CsO8 hexagonal bipyramids, faces with four equivalent CsO12 cuboctahedra, faces with two equivalent CsO8 hexagonal bipyramids, and faces with eight equivalent UO5 square pyramids. There are four shorter (3.10 Å) and eight longer (3.33 Å) Cs–O bond lengths. U4+ is bonded to five O2- atoms to form UO5 square pyramids that share corners with five equivalent UO5 square pyramids, edges with four equivalent CsO8 hexagonal bipyramids, and faces with four equivalent CsO12 cuboctahedra. All U–O bond lengths are 2.21 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to four Cs1+ and two equivalent U4+ atoms. In the second O2- site, O2- is bonded to four equivalent Cs1+ and two equivalent U4+ atoms to form a mixture of distorted corner and edge-sharing OCs4U2 octahedra. The corner-sharing octahedral tilt angles are 0°.