Materials Data on NaCaAlSi2O7 by Materials Project

Abstract

CaNaAlSi2O7 crystallizes in the orthorhombic P2_12_12_1 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 2.18–2.89 Å. Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.27–2.68 Å. Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with four SiO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.78–1.83 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 is one shorter (1.58 Å) and three longer (1.67 Å) Si–O bond length. 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 1.59–1.70 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to one Na1+, one Ca2+, and two Si4+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ca2+, one Al3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ca2+, one Al3+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted see-saw-like geometry to two equivalent Na1+, one Al3+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ca2+, one Al3+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Na1+, one Ca2+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Ca2+, and one Si4+ atom.