Materials Data on Na4SiSe4 by Materials Project
Na4SiSe4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are three inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 4-coordinate geometry to four Se2- atoms. There are two shorter (2.87 Å) and two longer (3.15 Å) Na–Se bond lengths. In the second Na1+ site, Na1+ is bonded in a distorted pentagonal planar geometry to five Se2- atoms. There are a spread of Na–Se bond distances ranging from 2.98–3.10 Å. In the third Na1+ site, Na1+ is bonded in a 5-coordinate geometry to five Se2- atoms. There are a spread of Na–Se bond distances ranging from 2.92–3.23 Å. Si4+ is bonded in a tetrahedral geometry to four Se2- atoms. There are three shorter (2.30 Å) and one longer (2.31 Å) Si–Se bond lengths. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to four Na1+ and one Si4+ atom. In the second Se2- site, Se2- is bonded to five Na1+ and one Si4+ atom to form a mixture of distorted edge and corner-sharing SeNa5Si octahedra. The corner-sharing octahedra tilt angles range from 0–52°. In the third Se2- site, Se2- is bonded in a 6-coordinate geometry to five Na1+ and one Si4+ atom.