Materials Data on Na7Ti11O24 by Materials Project
Na7Ti11O24 is Spinel-like structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to four O2- atoms to form NaO4 tetrahedra that share corners with eleven TiO6 octahedra. The corner-sharing octahedra tilt angles range from 52–67°. There are a spread of Na–O bond distances ranging from 2.19–2.22 Å. In the second Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are four shorter (2.27 Å) and two longer (2.52 Å) Na–O bond lengths. In the third Na1+ site, Na1+ is bonded to four O2- atoms to form NaO4 tetrahedra that share corners with eleven TiO6 octahedra. The corner-sharing octahedra tilt angles range from 51–69°. There are a spread of Na–O bond distances ranging from 2.17–2.20 Å. There are five inequivalent Ti+3.73+ sites. In the first Ti+3.73+ site, Ti+3.73+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six NaO4 tetrahedra and edges with five TiO6 octahedra. There are a spread of Ti–O bond distances ranging from 1.88–2.13 Å. In the second Ti+3.73+ site, Ti+3.73+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six equivalent NaO4 tetrahedra and edges with six TiO6 octahedra. There are a spread of Ti–O bond distances ranging from 2.02–2.04 Å. In the third Ti+3.73+ site, Ti+3.73+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six NaO4 tetrahedra and edges with four equivalent TiO6 octahedra. There are four shorter (1.97 Å) and two longer (2.03 Å) Ti–O bond lengths. In the fourth Ti+3.73+ site, Ti+3.73+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six NaO4 tetrahedra and edges with six TiO6 octahedra. There are four shorter (2.03 Å) and two longer (2.05 Å) Ti–O bond lengths. In the fifth Ti+3.73+ site, Ti+3.73+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six NaO4 tetrahedra and edges with six TiO6 octahedra. There are a spread of Ti–O bond distances ranging from 1.98–2.08 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded to one Na1+ and three Ti+3.73+ atoms to form distorted ONaTi3 tetrahedra that share corners with eleven ONaTi3 tetrahedra, a cornercorner with one ONa2Ti2 trigonal pyramid, and edges with three ONaTi3 tetrahedra. In the second O2- site, O2- is bonded to one Na1+ and three Ti+3.73+ atoms to form distorted ONaTi3 tetrahedra that share corners with eight ONaTi3 tetrahedra, corners with three ONa2Ti2 trigonal pyramids, and edges with three ONaTi3 tetrahedra. In the third O2- site, O2- is bonded to one Na1+ and three Ti+3.73+ atoms to form distorted ONaTi3 tetrahedra that share corners with eight ONaTi3 tetrahedra, corners with three ONa2Ti2 trigonal pyramids, and edges with three ONaTi3 tetrahedra. In the fourth O2- site, O2- is bonded to two Na1+ and two equivalent Ti+3.73+ atoms to form distorted ONa2Ti2 trigonal pyramids that share corners with eight ONaTi3 tetrahedra, corners with three ONa2Ti2 trigonal pyramids, and edges with two equivalent ONa2Ti2 trigonal pyramids. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Na1+ and three Ti+3.73+ atoms. In the sixth O2- site, O2- is bonded to two Na1+ and two Ti+3.73+ atoms to form distorted ONa2Ti2 trigonal pyramids that share corners with six ONaTi3 tetrahedra, corners with five ONa2Ti2 trigonal pyramids, and edges with two ONa2Ti2 trigonal pyramids. In the seventh O2- site, O2- is bonded to one Na1+ and three Ti+3.73+ atoms to form distorted ONaTi3 tetrahedra that share corners with seven ONaTi3 tetrahedra, corners with three ONa2Ti2 trigonal pyramids, and edges with three ONaTi3 tetrahedra.