Materials Data on Al4Si by Materials Project
Al4Si crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are six inequivalent Al sites. In the first Al site, Al is bonded to nine Al and three equivalent Si atoms to form distorted AlAl9Si3 cuboctahedra that share corners with six equivalent SiAl6 cuboctahedra, corners with twelve AlAl9Si3 cuboctahedra, edges with six equivalent SiAl6 cuboctahedra, edges with eighteen AlAl9Si3 cuboctahedra, and faces with twelve AlAl9Si3 cuboctahedra. There are three shorter (2.84 Å) and six longer (2.85 Å) Al–Al bond lengths. All Al–Si bond lengths are 2.73 Å. In the second Al site, Al is bonded to twelve Al atoms to form AlAl12 cuboctahedra that share corners with three equivalent SiAl6 cuboctahedra, corners with nine AlAl9Si3 cuboctahedra, edges with three equivalent SiAl6 cuboctahedra, edges with twenty-one AlAl9Si3 cuboctahedra, and faces with eighteen AlAl9Si3 cuboctahedra. There are six shorter (2.85 Å) and three longer (2.88 Å) Al–Al bond lengths. In the third Al site, Al is bonded to twelve Al atoms to form AlAl12 cuboctahedra that share corners with three equivalent SiAl6 cuboctahedra, corners with nine AlAl9Si3 cuboctahedra, edges with three equivalent SiAl6 cuboctahedra, edges with twenty-one AlAl9Si3 cuboctahedra, and faces with eighteen AlAl9Si3 cuboctahedra. There are three shorter (2.84 Å) and six longer (2.85 Å) Al–Al bond lengths. In the fourth Al site, Al is bonded to twelve Al atoms to form AlAl12 cuboctahedra that share corners with three equivalent SiAl6 cuboctahedra, corners with nine AlAl9Si3 cuboctahedra, edges with three equivalent SiAl6 cuboctahedra, edges with twenty-one AlAl9Si3 cuboctahedra, and faces with eighteen AlAl9Si3 cuboctahedra. There are a spread of Al–Al bond distances ranging from 2.84–2.88 Å. In the fifth Al site, Al is bonded to twelve Al atoms to form AlAl12 cuboctahedra that share corners with three equivalent SiAl6 cuboctahedra, corners with nine AlAl9Si3 cuboctahedra, edges with three equivalent SiAl6 cuboctahedra, edges with twenty-one AlAl9Si3 cuboctahedra, and faces with eighteen AlAl9Si3 cuboctahedra. There are three shorter (2.84 Å) and six longer (2.85 Å) Al–Al bond lengths. In the sixth Al site, Al is bonded to twelve Al atoms to form AlAl12 cuboctahedra that share corners with three equivalent SiAl6 cuboctahedra, corners with nine AlAl9Si3 cuboctahedra, edges with three equivalent SiAl6 cuboctahedra, edges with twenty-one AlAl9Si3 cuboctahedra, and faces with eighteen AlAl9Si3 cuboctahedra. There are a spread of Al–Al bond distances ranging from 2.84–2.88 Å. Si is bonded to six equivalent Al atoms to form distorted SiAl6 cuboctahedra that share corners with eighteen AlAl9Si3 cuboctahedra, edges with six equivalent SiAl6 cuboctahedra, and edges with eighteen AlAl9Si3 cuboctahedra.