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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Sr2Ge2Se5 by Materials Project

Sr2Ge2Se5 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 7-coordinate geometry to eight Se2- atoms. There are a spread of Sr–Se bond distances ranging from 3.10–3.75 Å. In the second Sr2+ site, Sr2+ is bonded in a 9-coordinate geometry to nine Se2- atoms. There are a spread of Sr–Se bond distances ranging from 3.17–3.67 Å. There are two inequivalent Ge3+ sites. In the first Ge3+ site, Ge3+ is bonded in a trigonal non-coplanar geometry to three Se2- atoms. There are a spread of Ge–Se bond distances ranging from 2.36–2.41 Å. In the second Ge3+ site, Ge3+ is bonded in a trigonal non-coplanar geometry to three Se2- atoms. There are a spread of Ge–Se bond distances ranging from 2.37–2.48 Å. There are five inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to four Sr2+ and one Ge3+ atom. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to two Sr2+ and two equivalent Ge3+ atoms. In the third Se2- site, Se2- is bonded in a 5-coordinate geometry to four Sr2+ and one Ge3+ atom. In the fourth Se2- site, Se2- is bonded in a 4-coordinate geometry to three Sr2+ and one Ge3+ atom. In the fifth Se2- site, Se2- is bonded in a 4-coordinate geometry to four Sr2+ and one Ge3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr2GeSe4 by Materials Project

Sr2GeSe4 crystallizes in the orthorhombic Ama2 space group. The structure is three-dimensional. there are two inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded to seven Se2- atoms to form distorted SrSe7 pentagonal bipyramids that share corners with six equivalent SrSe7 pentagonal bipyramids, corners with three equivalent GeSe4 tetrahedra, and edges with two equivalent GeSe4 tetrahedra. There are a spread of Sr–Se bond distances ranging from 3.02–3.60 Å. In the second Sr2+ site, Sr2+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of Sr–Se bond distances ranging from 3.08–3.62 Å. Ge4+ is bonded to four Se2- atoms to form GeSe4 tetrahedra that share corners with three equivalent SrSe7 pentagonal bipyramids and edges with two equivalent SrSe7 pentagonal bipyramids. There are two shorter (2.39 Å) and two longer (2.41 Å) Ge–Se bond lengths. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three Sr2+ and one Ge4+ atom to form SeSr3Ge trigonal pyramids that share corners with three equivalent SeSr4Ge trigonal bipyramids, corners with two equivalent SeSr3Ge trigonal pyramids, and edges with two equivalent SeSr4Ge trigonal bipyramids. In the second Se2- site, Se2- is bonded to four Sr2+ and one Ge4+ atom to form distorted SeSr4Ge trigonal bipyramids that share corners with four equivalent SeSr4Ge trigonal bipyramids, corners with three equivalent SeSr3Ge trigonal pyramids, and edges with two equivalent SeSr3Ge trigonal pyramids. In the third Se2- site, Se2- is bonded in a 5-coordinate geometry to four Sr2+ and one Ge4+ atom.

36 MATERIALS SCIENCE↗