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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Cr4GaCuSe8 by Materials Project

Cr4CuGaSe8 is Spinel-derived structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Cr3+ is bonded to six Se2- atoms to form CrSe6 octahedra that share corners with three equivalent CuSe4 tetrahedra, corners with three equivalent GaSe4 tetrahedra, and edges with six equivalent CrSe6 octahedra. There are three shorter (2.51 Å) and three longer (2.58 Å) Cr–Se bond lengths. Cu1+ is bonded to four equivalent Se2- atoms to form CuSe4 tetrahedra that share corners with twelve equivalent CrSe6 octahedra. The corner-sharing octahedral tilt angles are 56°. All Cu–Se bond lengths are 2.44 Å. Ga3+ is bonded to four equivalent Se2- atoms to form GaSe4 tetrahedra that share corners with twelve equivalent CrSe6 octahedra. The corner-sharing octahedral tilt angles are 59°. All Ga–Se bond lengths are 2.47 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three equivalent Cr3+ and one Cu1+ atom. In the second Se2- site, Se2- is bonded to three equivalent Cr3+ and one Ga3+ atom to form a mixture of distorted edge and corner-sharing SeCr3Ga trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr8Ga3CuSe16 by Materials Project

Cr8CuGa3Se16 is Spinel-derived structured and crystallizes in the tetragonal P-4m2 space group. The structure is three-dimensional. there are two inequivalent Cr+2.75+ sites. In the first Cr+2.75+ site, Cr+2.75+ is bonded to six Se2- atoms to form CrSe6 octahedra that share corners with two equivalent CuSe4 tetrahedra, corners with four GaSe4 tetrahedra, and edges with six CrSe6 octahedra. There are a spread of Cr–Se bond distances ranging from 2.53–2.59 Å. In the second Cr+2.75+ site, Cr+2.75+ is bonded to six Se2- atoms to form CrSe6 octahedra that share a cornercorner with one CuSe4 tetrahedra, corners with five GaSe4 tetrahedra, and edges with six CrSe6 octahedra. There are a spread of Cr–Se bond distances ranging from 2.53–2.58 Å. Cu1+ is bonded to four equivalent Se2- atoms to form CuSe4 tetrahedra that share corners with twelve CrSe6 octahedra. The corner-sharing octahedra tilt angles range from 57–58°. All Cu–Se bond lengths are 2.47 Å. There are two inequivalent Ga3+ sites. In the first Ga3+ site, Ga3+ is bonded to four equivalent Se2- atoms to form GaSe4 tetrahedra that share corners with twelve CrSe6 octahedra. The corner-sharing octahedral tilt angles are 58°. All Ga–Se bond lengths are 2.51 Å. In the second Ga3+ site, Ga3+ is bonded to four Se2- atoms to form GaSe4 tetrahedra that share corners with twelve CrSe6 octahedra. The corner-sharing octahedra tilt angles range from 59–60°. There are two shorter (2.51 Å) and two longer (2.52 Å) Ga–Se bond lengths. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three Cr+2.75+ and one Cu1+ atom. In the second Se2- site, Se2- is bonded to three Cr+2.75+ and one Ga3+ atom to form a mixture of distorted corner and edge-sharing SeCr3Ga trigonal pyramids. In the third Se2- site, Se2- is bonded to three equivalent Cr+2.75+ and one Ga3+ atom to form a mixture of distorted corner and edge-sharing SeCr3Ga trigonal pyramids. In the fourth Se2- site, Se2- is bonded to three equivalent Cr+2.75+ and one Ga3+ atom to form a mixture of distorted corner and edge-sharing SeCr3Ga trigonal pyramids.

36 MATERIALS SCIENCE↗