DOI: 10.17188/1708816
title: Materials Data on CaAl4Si2O11 by Materials Project

description: CaAl4Si2O11 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. Ca2+ is bonded to twelve O2- atoms to form CaO12 cuboctahedra that share corners with six equivalent CaO12 cuboctahedra, edges with two equivalent AlO6 octahedra, edges with four SiO6 octahedra, and faces with six AlO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.63–2.75 Å. There are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent AlO6 octahedra, corners with four SiO6 octahedra, faces with three equivalent CaO12 cuboctahedra, and a faceface with one AlO6 octahedra. The corner-sharing octahedra tilt angles range from 50–56°. There are a spread of Al–O bond distances ranging from 1.87–1.96 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent AlO6 octahedra, corners with four SiO6 octahedra, faces with three equivalent CaO12 cuboctahedra, and a faceface with one AlO6 octahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Al–O bond distances ranging from 1.88–1.97 Å. In the third Al3+ site, Al3+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Al–O bond distances ranging from 1.74–1.95 Å. In the fourth Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with four AlO6 octahedra, edges with two equivalent CaO12 cuboctahedra, and edges with four SiO6 octahedra. The corner-sharing octahedral tilt angles are 56°. There are a spread of Al–O bond distances ranging from 1.88–1.93 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to six O2- atoms to form SiO6 octahedra that share corners with four AlO6 octahedra, edges with two equivalent CaO12 cuboctahedra, edges with two equivalent AlO6 octahedra, and edges with two equivalent SiO6 octahedra. The corner-sharing octahedra tilt angles range from 50–54°. There are a spread of Si–O bond distances ranging from 1.77–1.88 Å. In the second Si4+ site, Si4+ is bonded to six O2- atoms to form SiO6 octahedra that share corners with four AlO6 octahedra, edges with two equivalent CaO12 cuboctahedra, edges with two equivalent AlO6 octahedra, and edges with two equivalent SiO6 octahedra. The corner-sharing octahedra tilt angles range from 50–54°. There are a spread of Si–O bond distances ranging from 1.78–1.88 Å. There are eleven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, two Al3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Al3+, and two Si4+ atoms. In the third O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Ca2+ and three Al3+ atoms. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Ca2+ and three Al3+ atoms. In the fifth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Ca2+ and three Al3+ atoms. In the sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Al3+ and two Si4+ atoms. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to one Al3+ and two Si4+ atoms. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, two Al3+, and one Si4+ atom. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, two Al3+, and one Si4+ atom. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Al3+, and two Si4+ atoms. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, two Al3+, and one Si4+ atom.