Materials Data on NaCr(SiO3)2 by Materials Project
NaCrSi2O6 is Esseneite structured and crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.39–2.89 Å. Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six equivalent SiO4 tetrahedra and edges with two equivalent CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.98–2.09 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent CrO6 octahedra and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 34–60°. There are a spread of Si–O bond distances ranging from 1.61–1.66 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Na1+ and two equivalent Si4+ atoms. In the second O2- site, O2- is bonded in a distorted T-shaped geometry to one Na1+, one Cr3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, two equivalent Cr3+, and one Si4+ atom.