Materials Data on Si by Materials Project

Abstract

Si is alpha Samarium structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are eight inequivalent Si sites. In the first Si site, Si is bonded to twelve Si atoms to form a mixture of corner, edge, and face-sharing SiSi12 cuboctahedra. There are six shorter (2.69 Å) and six longer (2.76 Å) Si–Si bond lengths. In the second Si site, Si is bonded to twelve Si atoms to form a mixture of corner, edge, and face-sharing SiSi12 cuboctahedra. There are a spread of Si–Si bond distances ranging from 2.69–2.77 Å. In the third Si site, Si is bonded to twelve Si atoms to form a mixture of corner, edge, and face-sharing SiSi12 cuboctahedra. All Si–Si bond lengths are 2.69 Å. In the fourth Si site, Si is bonded to twelve Si atoms to form SiSi12 cuboctahedra that share corners with fifteen SiSi16 cuboctahedra, edges with twenty-one SiSi16 cuboctahedra, and faces with nineteen SiSi12 cuboctahedra. There are a spread of Si–Si bond distances ranging from 2.69–2.77 Å. In the fifth Si site, Si is bonded to twelve Si atoms to form a mixture of corner, edge, and face-sharing SiSi12 cuboctahedra. There are six shorter (2.69 Å) and three longer (2.76 Å) Si–Si bond lengths. In the sixth Si site, Si is bonded to twelve Si atoms to form SiSi12 cuboctahedra that share corners with twenty-three SiSi16 cuboctahedra, edges with sixteen SiSi16 cuboctahedra, and faces with twenty-three SiSi12 cuboctahedra. There are six shorter (2.69 Å) and three longer (2.76 Å) Si–Si bond lengths. In the seventh Si site, Si is bonded to twelve Si atoms to form SiSi12 cuboctahedra that share corners with twenty SiSi16 cuboctahedra, edges with nineteen SiSi12 cuboctahedra, and faces with twenty-two SiSi12 cuboctahedra. There are six shorter (2.69 Å) and three longer (2.77 Å) Si–Si bond lengths. In the eighth Si site, Si is bonded to sixteen Si atoms to form SiSi16 cuboctahedra that share corners with twenty-five SiSi12 cuboctahedra, edges with twenty-one SiSi16 cuboctahedra, and faces with thirty-five SiSi16 cuboctahedra. There are a spread of Si–Si bond distances ranging from 2.69–5.37 Å.