Materials Data on Na3Si34 by Materials Project
(Na)2NaSi34 is Matlockite-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional and consists of six sodium molecules and one NaSi34 framework. In the NaSi34 framework, Na is bonded in a 8-coordinate geometry to twenty Si atoms. There are a spread of Na–Si bond distances ranging from 3.21–3.38 Å. There are six inequivalent Si sites. In the first Si site, Si is bonded to four Si atoms to form corner-sharing SiSi4 tetrahedra. There are one shorter (2.36 Å) and three longer (2.37 Å) Si–Si bond lengths. In the second Si site, Si is bonded in a 5-coordinate geometry to one Na and four Si atoms. All Si–Si bond lengths are 2.37 Å. In the third Si site, Si is bonded in a distorted pentagonal planar geometry to one Na and four Si atoms. In the fourth Si site, Si is bonded to four Si atoms to form corner-sharing SiSi4 tetrahedra. There are two shorter (2.36 Å) and one longer (2.40 Å) Si–Si bond lengths. In the fifth Si site, Si is bonded in a 4-coordinate geometry to one Na and four Si atoms. There are one shorter (2.37 Å) and one longer (2.41 Å) Si–Si bond lengths. In the sixth Si site, Si is bonded to four Si atoms to form corner-sharing SiSi4 tetrahedra. Both Si–Si bond lengths are 2.36 Å.