Materials Data on NaCaAlSi2O7 by Materials Project

Abstract

CaNaAlSi2O7 crystallizes in the tetragonal P-42_1m space group. The structure is three-dimensional. Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.18–2.65 Å. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.26–2.86 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four equivalent O2- atoms to form AlO4 tetrahedra that share corners with four equivalent SiO4 tetrahedra. All Al–O bond lengths are 1.80 Å. In the second Al3+ site, Al3+ is bonded to four equivalent O2- atoms to form AlO4 tetrahedra that share corners with four equivalent SiO4 tetrahedra. All Al–O bond lengths are 1.80 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one SiO4 tetrahedra and corners with two equivalent AlO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.63–1.66 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one SiO4 tetrahedra and corners with two equivalent AlO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.55–1.70 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to two equivalent Na1+ and two equivalent Si4+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to two equivalent Ca2+ and two equivalent Si4+ atoms. In the third O2- site, O2- is bonded in a distorted see-saw-like geometry to two equivalent Ca2+, one Al3+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to three equivalent Ca2+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent Na1+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one Al3+, and one Si4+ atom.