Materials Data on NaSi2O7 by Materials Project
NaSi2O7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are three inequivalent Na sites. In the first Na site, Na is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Na–O bond distances ranging from 2.31–2.99 Å. In the second Na site, Na is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Na–O bond distances ranging from 2.31–3.00 Å. In the third Na site, Na is bonded to four O atoms to form distorted NaO4 trigonal pyramids that share corners with three SiO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.16–2.54 Å. There are four inequivalent Si sites. In the first Si site, Si is bonded to four O atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.63–1.65 Å. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three SiO4 tetrahedra and a cornercorner with one NaO4 trigonal pyramid. There is three shorter (1.60 Å) and one longer (1.76 Å) Si–O bond length. In the third Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three SiO4 tetrahedra and a cornercorner with one NaO4 trigonal pyramid. There are a spread of Si–O bond distances ranging from 1.62–1.65 Å. In the fourth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three SiO4 tetrahedra and a cornercorner with one NaO4 trigonal pyramid. There are a spread of Si–O bond distances ranging from 1.62–1.65 Å. There are fourteen inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the second O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the third O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the fourth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the fifth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the sixth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the seventh O site, O is bonded in a single-bond geometry to one Si atom. In the eighth O site, O is bonded in a distorted trigonal non-coplanar geometry to one Na, one Si, and one O atom. The O–O bond length is 1.35 Å. In the ninth O site, O is bonded in a bent 120 degrees geometry to one Na and one Si atom. In the tenth O site, O is bonded in a bent 150 degrees geometry to one Na and one Si atom. In the eleventh O site, O is bonded in a 3-coordinate geometry to two Na and one O atom. In the twelfth O site, O is bonded in a water-like geometry to two Na atoms. In the thirteenth O site, O is bonded in a distorted single-bond geometry to one Na atom. In the fourteenth O site, O is bonded in a distorted water-like geometry to two Na atoms.