Materials Data on Na2U2O7 by Materials Project

Dataset · Sat May 02 04:00:00 EDT 2020

DOI:https://doi.org/10.17188/1740873· OSTI ID:1740873

Na2U2O7 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.37–2.84 Å. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with four equivalent UO6 octahedra and corners with two equivalent UO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 54°. There are four shorter (2.41 Å) and two longer (2.87 Å) Na–O bond lengths. In the third Na1+ site, Na1+ is bonded in a 6-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.47–3.00 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 two equivalent NaO6 octahedra, corners with two equivalent UO6 octahedra, corners with two equivalent UO7 pentagonal bipyramids, and edges with two equivalent UO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 51–54°. There are a spread of U–O bond distances ranging from 1.90–2.21 Å. In the second U6+ site, U6+ is bonded to seven O2- atoms to form distorted UO7 pentagonal bipyramids that share a cornercorner with one NaO6 octahedra, corners with two equivalent UO6 octahedra, edges with two equivalent UO6 octahedra, and edges with two equivalent UO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 36–64°. There are a spread of U–O bond distances ranging from 1.87–2.59 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+ and three U6+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+ and three U6+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to three Na1+ and one U6+ atom. In the fourth O2- site, O2- is bonded to three Na1+ and one U6+ atom to form a mixture of distorted edge and corner-sharing ONa3U tetrahedra. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+ and one U6+ atom.

• Research Organization: LBNL Materials Project; Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• Contributing Organization: The Materials Project; MIT; UC Berkeley; Duke; U Louvain
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 1740873
• Report Number(s): mp-1190548
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
Na-O-U
Na2U2O7
crystal structure