Materials Data on Na2SeO9 by Materials Project

Na2SeO9 crystallizes in the tetragonal P4_122 space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded to six O atoms to form distorted edge-sharing NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.30–2.62 Å. In the second Na site, Na is bonded in a 6-coordinate geometry to six O atoms. There are two shorter (2.53 Å) and four longer (2.57 Å) Na–O bond lengths. Se is bonded in a see-saw-like geometry to four O atoms. There is two shorter (1.71 Å) and two longer (2.06 Å) Se–O bond length. There are five inequivalent O sites. In the first O site, O is bonded in a distorted T-shaped geometry to two equivalent Na and one Se atom. In the second O site, O is bonded in a bent 120 degrees geometry to one Na and one O atom. The O–O bond length is 1.27 Å. In the third O site, O is bonded in a distorted bent 120 degrees geometry to two equivalent Se atoms. In the fourth O site, O is bonded in a distorted L-shaped geometry to one Na and one O atom. The O–O bond length is 1.25 Å. In the fifth O site, O is bonded in a trigonal planar geometry to two equivalent Na and one O atom.