Materials Data on Al4SiC4 by Materials Project
Al4SiC4 is Aluminum carbonitride-like structured and crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. there are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four C4- atoms to form distorted AlC4 trigonal pyramids that share corners with three equivalent AlC4 tetrahedra, corners with three equivalent SiC4 tetrahedra, corners with seven AlC4 trigonal pyramids, and edges with three equivalent SiC4 tetrahedra. There are one shorter (1.87 Å) and three longer (2.27 Å) Al–C bond lengths. In the second Al3+ site, Al3+ is bonded to four C4- atoms to form a mixture of edge and corner-sharing AlC4 tetrahedra. There are three shorter (1.97 Å) and one longer (2.09 Å) Al–C bond lengths. In the third Al3+ site, Al3+ is bonded to four C4- atoms to form a mixture of distorted edge and corner-sharing AlC4 trigonal pyramids. There are three shorter (1.93 Å) and one longer (2.40 Å) Al–C bond lengths. In the fourth Al3+ site, Al3+ is bonded to four C4- atoms to form AlC4 tetrahedra that share corners with three equivalent SiC4 tetrahedra, corners with seven AlC4 tetrahedra, and corners with three equivalent AlC4 trigonal pyramids. There are three shorter (2.01 Å) and one longer (2.03 Å) Al–C bond lengths. Si4+ is bonded to four C4- atoms to form SiC4 tetrahedra that share corners with three equivalent AlC4 tetrahedra, corners with six equivalent SiC4 tetrahedra, corners with three equivalent AlC4 trigonal pyramids, and edges with three equivalent AlC4 trigonal pyramids. There is one shorter (1.75 Å) and three longer (2.14 Å) Si–C bond length. There are four inequivalent C4- sites. In the first C4- site, C4- is bonded in a 5-coordinate geometry to five Al3+ atoms. In the second C4- site, C4- is bonded to three equivalent Al3+ and three equivalent Si4+ atoms to form CAl3Si3 octahedra that share corners with three equivalent CAl3Si tetrahedra and edges with six equivalent CAl3Si3 octahedra. In the third C4- site, C4- is bonded to five Al3+ atoms to form CAl5 trigonal bipyramids that share corners with three equivalent CAl3Si tetrahedra and corners with six equivalent CAl5 trigonal bipyramids. In the fourth C4- site, C4- is bonded to three equivalent Al3+ and one Si4+ atom to form CAl3Si tetrahedra that share corners with three equivalent CAl3Si3 octahedra, corners with six equivalent CAl3Si tetrahedra, and corners with three equivalent CAl5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 64°.