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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on CaSi2 by Materials Project

CaSi2 is alpha boron-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Ca is bonded in a 7-coordinate geometry to seven Si atoms. There are a spread of Ca–Si bond distances ranging from 3.01–3.12 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded to three equivalent Ca and three equivalent Si atoms to form distorted edge-sharing SiCa3Si3 octahedra. All Si–Si bond lengths are 2.39 Å. In the second Si site, Si is bonded in a 7-coordinate geometry to four equivalent Ca and three equivalent Si atoms. All Si–Si bond lengths are 2.44 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CaSi2 by Materials Project

CaSi2 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Ca is bonded in a 8-coordinate geometry to eight equivalent Si atoms. There are six shorter (3.10 Å) and two longer (3.13 Å) Ca–Si bond lengths. Si is bonded in a 7-coordinate geometry to four equivalent Ca and three equivalent Si atoms. All Si–Si bond lengths are 2.42 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CaSi2 by Materials Project

CaSi2 is hexagonal omega structure structured and crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Ca is bonded to six equivalent Si atoms to form distorted CaSi6 octahedra that share corners with six equivalent SiCa3Si3 octahedra, edges with six equivalent CaSi6 octahedra, and edges with six equivalent SiCa3Si3 octahedra. The corner-sharing octahedral tilt angles are 21°. All Ca–Si bond lengths are 3.04 Å. Si is bonded to three equivalent Ca and three equivalent Si atoms to form distorted SiCa3Si3 octahedra that share corners with three equivalent CaSi6 octahedra, corners with three equivalent SiCa3Si3 octahedra, edges with three equivalent CaSi6 octahedra, and edges with nine equivalent SiCa3Si3 octahedra. The corner-sharing octahedra tilt angles range from 0–21°. All Si–Si bond lengths are 2.40 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CaSi2 by Materials Project

CaSi2 is hexagonal omega structure-like structured and crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Ca is bonded to twelve Si atoms to form a mixture of edge and face-sharing CaSi12 cuboctahedra. There are four shorter (3.11 Å) and eight longer (3.21 Å) Ca–Si bond lengths. There are four inequivalent Si sites. In the first Si site, Si is bonded in a 9-coordinate geometry to six equivalent Ca and three Si atoms. There are one shorter (2.29 Å) and two longer (2.40 Å) Si–Si bond lengths. In the second Si site, Si is bonded in a 9-coordinate geometry to six equivalent Ca and three Si atoms. There are one shorter (2.29 Å) and two longer (2.40 Å) Si–Si bond lengths. In the third Si site, Si is bonded in a 9-coordinate geometry to six equivalent Ca and three Si atoms. In the fourth Si site, Si is bonded in a 9-coordinate geometry to six equivalent Ca and three Si atoms. There are two shorter (3.11 Å) and four longer (3.21 Å) Si–Ca bond lengths. There are one shorter (2.29 Å) and two longer (2.40 Å) Si–Si bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CaSi2(BO4)2 by Materials Project

CaB2Si2O8 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.43–2.54 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 SiO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.46–1.51 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one SiO4 tetrahedra and corners with three equivalent BO4 tetrahedra. There is two shorter (1.63 Å) and two longer (1.64 Å) Si–O bond length. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one B3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one B3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two equivalent B3+ atoms. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Si4+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one B3+, and one Si4+ atom.

36 MATERIALS SCIENCE↗