Materials Data on Na4B2O5 by Materials Project
Na4B2O5 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.38–2.73 Å. In the second Na1+ site, Na1+ is bonded to five O2- atoms to form distorted edge-sharing NaO5 trigonal bipyramids. There are a spread of Na–O bond distances ranging from 2.34–2.66 Å. B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.37 Å) and one longer (1.45 Å) B–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Na1+ and two equivalent B3+ atoms. In the second O2- site, O2- is bonded in a distorted single-bond geometry to five Na1+ and one B3+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to five Na1+ and one B3+ atom.