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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on La2USe4 by Materials Project

ULa2Se4 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. U3+ is bonded to eight equivalent Se2- atoms to form distorted USe8 hexagonal bipyramids that share corners with eight equivalent LaSe8 hexagonal bipyramids, edges with four equivalent USe8 hexagonal bipyramids, and faces with eight equivalent LaSe8 hexagonal bipyramids. There are four shorter (3.02 Å) and four longer (3.13 Å) U–Se bond lengths. La+2.50+ is bonded to eight equivalent Se2- atoms to form distorted LaSe8 hexagonal bipyramids that share corners with four equivalent USe8 hexagonal bipyramids, corners with four equivalent LaSe8 hexagonal bipyramids, edges with four equivalent LaSe8 hexagonal bipyramids, faces with four equivalent USe8 hexagonal bipyramids, and faces with four equivalent LaSe8 hexagonal bipyramids. There are a spread of La–Se bond distances ranging from 3.04–3.23 Å. Se2- is bonded to two equivalent U3+ and four equivalent La+2.50+ atoms to form a mixture of distorted corner, edge, and face-sharing SeLa4U2 octahedra. The corner-sharing octahedra tilt angles range from 15–50°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La2U2Se9 by Materials Project

U2La2Se9 crystallizes in the orthorhombic Pmma space group. The structure is three-dimensional. U6+ is bonded in a 9-coordinate geometry to nine Se2- atoms. There are a spread of U–Se bond distances ranging from 2.87–3.07 Å. There are two inequivalent La3+ sites. In the first La3+ site, La3+ is bonded in a 10-coordinate geometry to ten Se2- atoms. There are a spread of La–Se bond distances ranging from 3.04–3.37 Å. In the second La3+ site, La3+ is bonded in a 10-coordinate geometry to eight Se2- atoms. There are a spread of La–Se bond distances ranging from 3.11–3.16 Å. There are five inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted see-saw-like geometry to two equivalent U6+ and two equivalent La3+ atoms. In the second Se2- site, Se2- is bonded to two equivalent U6+ and two La3+ atoms to form a mixture of distorted edge and corner-sharing SeLa2U2 trigonal pyramids. In the third Se2- site, Se2- is bonded in a 6-coordinate geometry to two equivalent U6+, two equivalent La3+, and two equivalent Se2- atoms. There are one shorter (2.68 Å) and one longer (2.73 Å) Se–Se bond lengths. In the fourth Se2- site, Se2- is bonded in a 6-coordinate geometry to two equivalent U6+ and two equivalent La3+ atoms. In the fifth Se2- site, Se2- is bonded in a 6-coordinate geometry to two equivalent U6+, two La3+, and two equivalent Se2- atoms. There are one shorter (2.78 Å) and one longer (2.80 Å) Se–Se bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La2USe5 by Materials Project

ULa2Se5 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. U4+ is bonded to seven Se2- atoms to form distorted edge-sharing USe7 pentagonal bipyramids. There are a spread of U–Se bond distances ranging from 2.81–3.05 Å. La3+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of La–Se bond distances ranging from 3.08–3.25 Å. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to two equivalent U4+ and two equivalent La3+ atoms to form distorted SeLa2U2 trigonal pyramids that share corners with six SeLa4U square pyramids, corners with two equivalent SeLa4U trigonal bipyramids, corners with six equivalent SeLa2U2 trigonal pyramids, edges with three SeLa4U square pyramids, edges with two equivalent SeLa4U trigonal bipyramids, and an edgeedge with one SeLa2U2 trigonal pyramid. In the second Se2- site, Se2- is bonded to one U4+ and four equivalent La3+ atoms to form distorted SeLa4U trigonal bipyramids that share corners with six SeLa4U square pyramids, corners with four equivalent SeLa4U trigonal bipyramids, corners with four equivalent SeLa2U2 trigonal pyramids, edges with six SeLa4U square pyramids, and edges with four equivalent SeLa2U2 trigonal pyramids. In the third Se2- site, Se2- is bonded to one U4+ and four equivalent La3+ atoms to form SeLa4U square pyramids that share corners with four equivalent SeLa4U square pyramids, corners with five equivalent SeLa4U trigonal bipyramids, corners with eight equivalent SeLa2U2 trigonal pyramids, edges with three SeLa4U square pyramids, edges with two equivalent SeLa4U trigonal bipyramids, edges with two equivalent SeLa2U2 trigonal pyramids, and a faceface with one SeLa4U square pyramid. In the fourth Se2- site, Se2- is bonded to one U4+ and four equivalent La3+ atoms to form distorted SeLa4U square pyramids that share corners with eight SeLa4U square pyramids, a cornercorner with one SeLa4U trigonal bipyramid, corners with four equivalent SeLa2U2 trigonal pyramids, an edgeedge with one SeLa4U square pyramid, edges with four equivalent SeLa4U trigonal bipyramids, edges with four equivalent SeLa2U2 trigonal pyramids, and a faceface with one SeLa4U square pyramid.

36 MATERIALS SCIENCE↗