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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Na3Eu2(GeSe3)2 by Materials Project

Na3Eu2(GeSe3)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six Se2- atoms to form NaSe6 octahedra that share corners with four equivalent EuSe6 octahedra, edges with four equivalent EuSe6 octahedra, and edges with six NaSe6 octahedra. The corner-sharing octahedral tilt angles are 2°. There are a spread of Na–Se bond distances ranging from 3.08–3.17 Å. In the second Na1+ site, Na1+ is bonded to six Se2- atoms to form NaSe6 octahedra that share corners with four equivalent EuSe6 octahedra, edges with four equivalent EuSe6 octahedra, and edges with six equivalent NaSe6 octahedra. The corner-sharing octahedral tilt angles are 1°. There are four shorter (3.12 Å) and two longer (3.13 Å) Na–Se bond lengths. Eu+2.50+ is bonded to six Se2- atoms to form EuSe6 octahedra that share corners with six NaSe6 octahedra, edges with three equivalent EuSe6 octahedra, and edges with six NaSe6 octahedra. The corner-sharing octahedra tilt angles range from 1–2°. There are two shorter (3.12 Å) and four longer (3.13 Å) Eu–Se bond lengths. Ge2+ is bonded in a trigonal non-coplanar geometry to three Se2- atoms. There are one shorter (2.52 Å) and two longer (2.53 Å) Ge–Se bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three Na1+, two equivalent Eu+2.50+, and one Ge2+ atom to form a mixture of edge and corner-sharing SeNa3Eu2Ge octahedra. The corner-sharing octahedra tilt angles range from 0–87°. In the second Se2- site, Se2- is bonded to three Na1+, two equivalent Eu+2.50+, and one Ge2+ atom to form a mixture of edge and corner-sharing SeNa3Eu2Ge octahedra. The corner-sharing octahedra tilt angles range from 0–87°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2EuGeSe4 by Materials Project

Na2EuGeSe4 crystallizes in the tetragonal I-42m space group. The structure is three-dimensional. Na1+ is bonded in a 8-coordinate geometry to eight equivalent Se2- atoms. There are four shorter (3.03 Å) and four longer (3.58 Å) Na–Se bond lengths. Eu2+ is bonded in a 8-coordinate geometry to eight equivalent Se2- atoms. There are four shorter (3.07 Å) and four longer (3.54 Å) Eu–Se bond lengths. Ge4+ is bonded in a tetrahedral geometry to four equivalent Se2- atoms. All Ge–Se bond lengths are 2.41 Å. Se2- is bonded in a 4-coordinate geometry to four equivalent Na1+, two equivalent Eu2+, and one Ge4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na4Eu(GeSe3)2 by Materials Project

Na4Eu(GeSe3)2 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are four inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six Se2- atoms to form NaSe6 octahedra that share corners with two equivalent NaSe6 octahedra, corners with two equivalent EuSe6 octahedra, edges with two equivalent EuSe6 octahedra, and edges with eight NaSe6 octahedra. The corner-sharing octahedra tilt angles range from 4–5°. There are a spread of Na–Se bond distances ranging from 3.05–3.12 Å. In the second Na1+ site, Na1+ is bonded to six Se2- atoms to form NaSe6 octahedra that share corners with two equivalent NaSe6 octahedra, corners with two equivalent EuSe6 octahedra, edges with two equivalent EuSe6 octahedra, and edges with eight NaSe6 octahedra. The corner-sharing octahedral tilt angles are 5°. There are a spread of Na–Se bond distances ranging from 3.03–3.12 Å. In the third Na1+ site, Na1+ is bonded to six Se2- atoms to form NaSe6 octahedra that share corners with two equivalent NaSe6 octahedra, corners with two equivalent EuSe6 octahedra, edges with two equivalent EuSe6 octahedra, and edges with eight NaSe6 octahedra. The corner-sharing octahedral tilt angles are 4°. There are a spread of Na–Se bond distances ranging from 3.04–3.18 Å. In the fourth Na1+ site, Na1+ is bonded to six Se2- atoms to form NaSe6 octahedra that share corners with six NaSe6 octahedra, edges with three equivalent EuSe6 octahedra, and edges with six NaSe6 octahedra. The corner-sharing octahedra tilt angles range from 4–5°. There are four shorter (3.13 Å) and two longer (3.14 Å) Na–Se bond lengths. Eu2+ is bonded to six Se2- atoms to form EuSe6 octahedra that share corners with six NaSe6 octahedra and edges with nine NaSe6 octahedra. The corner-sharing octahedra tilt angles range from 4–5°. There are two shorter (3.11 Å) and four longer (3.12 Å) Eu–Se bond lengths. Ge3+ is bonded in a trigonal non-coplanar geometry to three Se2- atoms. There are one shorter (2.39 Å) and two longer (2.40 Å) Ge–Se bond lengths. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to four Na1+, one Eu2+, and one Ge3+ atom to form a mixture of edge and corner-sharing SeNa4EuGe octahedra. The corner-sharing octahedra tilt angles range from 0–89°. In the second Se2- site, Se2- is bonded to four Na1+, one Eu2+, and one Ge3+ atom to form a mixture of edge and corner-sharing SeNa4EuGe octahedra. The corner-sharing octahedra tilt angles range from 0–89°. In the third Se2- site, Se2- is bonded to four Na1+, one Eu2+, and one Ge3+ atom to form a mixture of edge and corner-sharing SeNa4EuGe octahedra. The corner-sharing octahedra tilt angles range from 0–88°.

36 MATERIALS SCIENCE↗