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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on SrGe2 by Materials Project

SrGe2 is Magnesium tetraboride-like structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Sr sites. In the first Sr site, Sr is bonded in a 9-coordinate geometry to nine Ge atoms. There are a spread of Sr–Ge bond distances ranging from 3.23–3.52 Å. In the second Sr site, Sr is bonded in a 11-coordinate geometry to eleven Ge atoms. There are a spread of Sr–Ge bond distances ranging from 3.36–3.63 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 8-coordinate geometry to five Sr and three Ge atoms. There are two shorter (2.58 Å) and one longer (2.64 Å) Ge–Ge bond lengths. In the second Ge site, Ge is bonded in a 8-coordinate geometry to five Sr and three Ge atoms. Both Ge–Ge bond lengths are 2.59 Å. In the third Ge site, Ge is bonded in a 8-coordinate geometry to five Sr and three Ge atoms. The Ge–Ge bond length is 2.57 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SrGe2 by Materials Project

SrGe2 is hexagonal omega structure structured and crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Sr is bonded to six equivalent Ge atoms to form SrGe6 octahedra that share corners with six equivalent GeSr3Ge3 octahedra, edges with six equivalent SrGe6 octahedra, and edges with six equivalent GeSr3Ge3 octahedra. The corner-sharing octahedral tilt angles are 18°. All Sr–Ge bond lengths are 3.19 Å. Ge is bonded to three equivalent Sr and three equivalent Ge atoms to form distorted GeSr3Ge3 octahedra that share corners with three equivalent SrGe6 octahedra, corners with three equivalent GeSr3Ge3 octahedra, edges with three equivalent SrGe6 octahedra, and edges with nine equivalent GeSr3Ge3 octahedra. The corner-sharing octahedra tilt angles range from 0–18°. All Ge–Ge bond lengths are 2.61 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SrGe2(BO4)2 by Materials Project

SrGe2(BO4)2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Sr2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Sr–O bond distances ranging from 2.55–2.64 Å. B3+ is bonded to four O2- atoms to form BO4 tetrahedra that share a cornercorner with one BO4 tetrahedra and corners with three equivalent GeO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.46–1.53 Å. Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share a cornercorner with one GeO4 tetrahedra and corners with three equivalent BO4 tetrahedra. There is two shorter (1.76 Å) and two longer (1.77 Å) Ge–O bond length. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Sr2+, one B3+, and one Ge4+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Sr2+, one B3+, and one Ge4+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent Ge4+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Sr2+ and two equivalent B3+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Sr2+, one B3+, and one Ge4+ atom.

36 MATERIALS SCIENCE↗