Materials Data on Ca3Al4SiO12 by Materials Project

Ca3Al4SiO12 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are three inequivalent Ca sites. In the first Ca site, Ca is bonded to six O atoms to form CaO6 octahedra that share a cornercorner with one SiO4 tetrahedra, corners with three AlO4 tetrahedra, edges with three equivalent CaO6 octahedra, and edges with three equivalent AlO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.24–2.34 Å. In the second Ca site, Ca is bonded to six O atoms to form CaO6 octahedra that share a cornercorner with one SiO4 tetrahedra, corners with three AlO4 tetrahedra, edges with three equivalent CaO6 octahedra, and edges with three equivalent AlO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.23–2.33 Å. In the third Ca site, Ca is bonded to six O atoms to form CaO6 octahedra that share corners with three equivalent SiO4 tetrahedra and corners with nine AlO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.37–2.96 Å. There are four inequivalent Al sites. In the first Al site, Al is bonded to six O atoms to form AlO6 octahedra that share a cornercorner with one SiO4 tetrahedra, corners with three AlO4 tetrahedra, and edges with six CaO6 octahedra. There are a spread of Al–O bond distances ranging from 1.84–2.12 Å. In the second Al site, Al is bonded to four O atoms to form AlO4 tetrahedra that share a cornercorner with one AlO6 octahedra, corners with five CaO6 octahedra, and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–73°. There is one shorter (1.77 Å) and three longer (1.81 Å) Al–O bond length. In the third Al site, Al is bonded to four O atoms to form AlO4 tetrahedra that share a cornercorner with one AlO6 octahedra, corners with five CaO6 octahedra, and corners with three equivalent AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 49–66°. There is one shorter (1.78 Å) and three longer (1.80 Å) Al–O bond length. In the fourth Al site, Al is bonded to four O atoms to form AlO4 tetrahedra that share a cornercorner with one AlO6 octahedra, corners with five CaO6 octahedra, and corners with three equivalent AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 50–66°. There is one shorter (1.79 Å) and three longer (1.80 Å) Al–O bond length. Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one AlO6 octahedra, corners with five CaO6 octahedra, and corners with three equivalent AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 49–66°. There is two shorter (1.66 Å) and two longer (1.67 Å) Si–O bond length. There are twelve inequivalent O sites. In the first O site, O is bonded in a rectangular see-saw-like geometry to two Ca, one Al, and one Si atom. In the second O site, O is bonded in a distorted rectangular see-saw-like geometry to two Ca and two Al atoms. In the third O site, O is bonded in a rectangular see-saw-like geometry to two Ca and two Al atoms. In the fourth O site, O is bonded in a distorted rectangular see-saw-like geometry to two Ca and two Al atoms. In the fifth O site, O is bonded in a 3-coordinate geometry to one Ca, one Al, and one Si atom. In the sixth O site, O is bonded in a 2-coordinate geometry to one Ca, one Al, and one Si atom. In the seventh O site, O is bonded in a trigonal planar geometry to one Ca and two Al atoms. In the eighth O site, O is bonded in a trigonal planar geometry to one Ca and two Al atoms. In the ninth O site, O is bonded in a distorted T-shaped geometry to two Ca and one Al atom. In the tenth O site, O is bonded in a distorted trigonal non-coplanar geometry to two Ca and one Al atom. In the eleventh O site, O is bonded in a distorted trigonal planar geometry to one Ca, one Al, and one Si atom. In the twelfth O site, O is bonded in a trigonal planar geometry to one Ca and two Al atoms.