Materials Data on Ca2Al2SiO7 by Materials Project

Abstract

Ca2Al2SiO7 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.28–2.61 Å. In the second Ca2+ site, Ca2+ is bonded in a 2-coordinate geometry to four O2- atoms. There are a spread of Ca–O bond distances ranging from 2.15–2.79 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 a cornercorner with one AlO5 square pyramid, corners with two equivalent SiO4 tetrahedra, and an edgeedge with one AlO5 square pyramid. There are a spread of Al–O bond distances ranging from 1.75–1.97 Å. In the second Al3+ site, Al3+ is bonded to five O2- atoms to form AlO5 square pyramids that share a cornercorner with one AlO4 tetrahedra, corners with two equivalent SiO4 tetrahedra, and an edgeedge with one AlO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.76–1.92 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent AlO5 square pyramids and corners with two equivalent AlO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.63–1.67 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to three Ca2+, one Al3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Al3+ and one Si4+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and two Al3+ atoms. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Al3+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two Al3+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and two Al3+ atoms.