DOI: 10.17188/1269343
title: Materials Data on Na2Si2O5 by Materials Project

description: Na2Si2O5 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with two equivalent NaO6 octahedra, corners with four SiO4 tetrahedra, corners with two equivalent NaO5 trigonal bipyramids, edges with two equivalent NaO6 octahedra, edges with two equivalent SiO4 tetrahedra, and edges with two equivalent NaO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 24°. There are a spread of Na–O bond distances ranging from 2.41–2.60 Å. In the second Na1+ site, Na1+ is bonded in a 5-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.32–3.03 Å. In the third Na1+ site, Na1+ is bonded to five O2- atoms to form distorted NaO5 square pyramids that share corners with four equivalent NaO5 square pyramids, corners with four SiO4 tetrahedra, and an edgeedge with one SiO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.41–2.60 Å. In the fourth Na1+ site, Na1+ is bonded to five O2- atoms to form distorted NaO5 trigonal bipyramids that share corners with two equivalent NaO6 octahedra, corners with four SiO4 tetrahedra, corners with two equivalent NaO5 trigonal bipyramids, edges with two equivalent NaO6 octahedra, an edgeedge with one SiO4 tetrahedra, and edges with two equivalent NaO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 32–71°. There are a spread of Na–O bond distances ranging from 2.32–2.61 Å. There are four 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 NaO6 octahedra, corners with three SiO4 tetrahedra, corners with two equivalent NaO5 trigonal bipyramids, and an edgeedge with one NaO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 53°. There is one shorter (1.60 Å) and three longer (1.66 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 NaO6 octahedra, corners with two equivalent NaO5 square pyramids, corners with three SiO4 tetrahedra, and a cornercorner with one NaO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 44°. There is one shorter (1.60 Å) and three longer (1.66 Å) Si–O bond length. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one NaO6 octahedra, a cornercorner with one NaO5 square pyramid, corners with three SiO4 tetrahedra, and an edgeedge with one NaO5 square pyramid. The corner-sharing octahedral tilt angles are 64°. There are a spread of Si–O bond distances ranging from 1.60–1.66 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one NaO6 octahedra, a cornercorner with one NaO5 square pyramid, corners with three SiO4 tetrahedra, a cornercorner with one NaO5 trigonal bipyramid, and edges with two equivalent NaO6 octahedra. The corner-sharing octahedral tilt angles are 67°. There is one shorter (1.59 Å) and three longer (1.66 Å) Si–O bond length. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two Si4+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two Si4+ atoms. In the third O2- site, O2- is bonded in a 5-coordinate geometry to four Na1+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two Si4+ atoms. In the fifth O2- site, O2- is bonded in a 5-coordinate geometry to four Na1+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two Si4+ atoms. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Na1+ and two Si4+ atoms. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to four Na1+ and one Si4+ atom. In the ninth O2- site, O2- is bonded in a 5-coordinate geometry to four Na1+ and one Si4+ atom. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two Si4+ atoms.