Materials Data on NaSi2BH2O7 by Materials Project
NaBSi2O5(OH)2 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. Na1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Na–O bond distances ranging from 2.32–2.59 Å. B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.31–1.43 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There is two shorter (1.63 Å) and two longer (1.64 Å) Si–O bond length. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.60–1.65 Å. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+ and two Si4+ atoms. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one B3+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one B3+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the sixth O2- site, O2- is bonded in a distorted water-like geometry to one Na1+ and two H1+ atoms. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Na1+ and one B3+ atom.