Materials Data on Na2Ca(SO4)2 by Materials Project
CaNa2(SO4)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.38–2.83 Å. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.35–2.74 Å. S6+ is bonded in a tetrahedral geometry to four O2- atoms. There is three shorter (1.49 Å) and one longer (1.50 Å) S–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three equivalent Na1+ and one S6+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one Ca2+, and one S6+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one Ca2+, and one S6+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to one Na1+, two equivalent Ca2+, and one S6+ atom.