Materials Data on Na3(CuO2)2 by Materials Project
Na3Cu2O4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to four O2- atoms to form distorted NaO4 tetrahedra that share a cornercorner with one NaO6 octahedra, corners with two equivalent NaO4 tetrahedra, edges with two equivalent NaO6 octahedra, and edges with two equivalent NaO4 tetrahedra. The corner-sharing octahedral tilt angles are 29°. There are a spread of Na–O bond distances ranging from 2.26–2.35 Å. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with two equivalent NaO4 tetrahedra, edges with two equivalent NaO6 octahedra, and edges with four equivalent NaO4 tetrahedra. There are four shorter (2.34 Å) and two longer (2.84 Å) Na–O bond lengths. Cu+2.50+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.92 Å) and two longer (1.93 Å) Cu–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to four Na1+ and two equivalent Cu+2.50+ atoms. In the second O2- site, O2- is bonded to three Na1+ and two equivalent Cu+2.50+ atoms to form a mixture of edge and corner-sharing ONa3Cu2 square pyramids.