Materials Data on Ca3Al2O6 by Materials Project
Ca3Al2O6 crystallizes in the cubic Pa-3 space group. The structure is three-dimensional. there are six inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six equivalent O2- atoms to form distorted CaO6 octahedra that share corners with six equivalent AlO4 tetrahedra. All Ca–O bond lengths are 2.38 Å. In the second Ca2+ site, Ca2+ is bonded to six equivalent O2- atoms to form distorted CaO6 octahedra that share corners with six equivalent AlO4 tetrahedra. All Ca–O bond lengths are 2.45 Å. In the third Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six equivalent AlO4 tetrahedra and a faceface with one CaO6 pentagonal pyramid. There are three shorter (2.35 Å) and three longer (2.41 Å) Ca–O bond lengths. In the fourth Ca2+ site, Ca2+ is bonded to six O2- atoms to form distorted CaO6 pentagonal pyramids that share corners with three equivalent AlO4 tetrahedra, edges with three equivalent AlO4 tetrahedra, and a faceface with one CaO6 octahedra. There are three shorter (2.46 Å) and three longer (2.54 Å) Ca–O bond lengths. In the fifth Ca2+ site, Ca2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Ca–O bond distances ranging from 2.27–2.45 Å. In the sixth Ca2+ site, Ca2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Ca–O bond distances ranging from 2.28–2.48 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with two equivalent CaO6 octahedra, corners with two equivalent AlO4 tetrahedra, and an edgeedge with one CaO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 41–44°. There is one shorter (1.76 Å) and three longer (1.78 Å) Al–O bond length. In the second Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with two CaO6 octahedra, a cornercorner with one CaO6 pentagonal pyramid, and corners with two equivalent AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 39–50°. There are a spread of Al–O bond distances ranging from 1.75–1.79 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Al3+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Al3+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and two Al3+ atoms. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Al3+ atom. In the fifth O2- site, O2- is bonded to two Ca2+ and two Al3+ atoms to form distorted corner-sharing OCa2Al2 tetrahedra. In the sixth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Ca2+ and one Al3+ atom.