DOE OSTI2020
Na11TiNb2Si4P2(O12F)2 is Esseneite-derived structured and crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are six inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 4-coordinate geometry to five O2- atoms. There are a spread of Na–O bond distances ranging from 2.29–2.96 Å. In the second Na1+ site, Na1+ is bonded to seven O2- and one F1- atom to form distorted NaO7F hexagonal bipyramids that share corners with two equivalent NaO7F hexagonal bipyramids, a cornercorner with one TiO4F2 octahedra, corners with two equivalent NaO4F2 octahedra, a cornercorner with one NaO4 tetrahedra, a cornercorner with one PO4 tetrahedra, edges with two equivalent NbO6 octahedra, an edgeedge with one NaO4 tetrahedra, and edges with four SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 49–69°. There are a spread of Na–O bond distances ranging from 2.35–2.90 Å. The Na–F bond length is 2.37 Å. In the third Na1+ site, Na1+ is bonded to four O2- atoms to form distorted NaO4 tetrahedra that share a cornercorner with one NaO7F hexagonal bipyramid, corners with two SiO4 tetrahedra, corners with three equivalent PO4 tetrahedra, and an edgeedge with one NaO7F hexagonal bipyramid. There are a spread of Na–O bond distances ranging from 2.26–2.45 Å. In the fourth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with two equivalent NbO6 octahedra, corners with four SiO4 tetrahedra, edges with two equivalent TiO4F2 octahedra, and edges with four equivalent NaO4F2 octahedra. The corner-sharing octahedral tilt angles are 53°. There are a spread of Na–O bond distances ranging from 2.36–2.65 Å. In the fifth Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.29–2.69 Å. In the sixth Na1+ site, Na1+ is bonded to four O2- and two equivalent F1- atoms to form NaO4F2 octahedra that share corners with two equivalent NaO7F hexagonal bipyramids, corners with two equivalent NbO6 octahedra, corners with two SiO4 tetrahedra, edges with two equivalent TiO4F2 octahedra, and edges with four NaO4F2 octahedra. The corner-sharing octahedra tilt angles range from 54–61°. There are a spread of Na–O bond distances ranging from 2.33–2.63 Å. There are one shorter (2.32 Å) and one longer (2.45 Å) Na–F bond lengths. Ti4+ is bonded to four O2- and two equivalent F1- atoms to form TiO4F2 octahedra that share corners with two equivalent NaO7F hexagonal bipyramids, corners with four SiO4 tetrahedra, and edges with six NaO4F2 octahedra. There are two shorter (2.00 Å) and two longer (2.06 Å) Ti–O bond lengths. Both Ti–F bond lengths are 2.00 Å. Nb+4.50+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share corners with three NaO6 octahedra, a cornercorner with one PO4 tetrahedra, corners with four SiO4 tetrahedra, and edges with two equivalent NaO7F hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 53–61°. There are a spread of Nb–O bond distances ranging from 1.81–2.27 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one TiO4F2 octahedra, corners with two NaO6 octahedra, corners with two equivalent NbO6 octahedra, a cornercorner with one NaO4 tetrahedra, a cornercorner with one SiO4 tetrahedra, and edges with two equivalent NaO7F hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 36–62°. There are a spread of Si–O bond distances ranging from 1.63–1.68 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one TiO4F2 octahedra, corners with two NaO6 octahedra, corners with two equivalent NbO6 octahedra, a cornercorner with one NaO4 tetrahedra, a cornercorner with one SiO4 tetrahedra, and edges with two equivalent NaO7F hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 28–69°. There are a spread of Si–O bond distances ranging from 1.62–1.67 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one NaO7F hexagonal bipyramid, a cornercorner with one NbO6 octahedra, and corners with three equivalent NaO4 tetrahedra. The corner-sharing octahedral tilt angles are 46°. There are a spread of P–O bond distances ranging from 1.55–1.59 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+, one Nb+4.50+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one Ti4+, and one Si4+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+, one Nb+4.50+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to three Na1+ and two Si4+ atoms. In the fifth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one Nb+4.50+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Nb+4.50+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+, one Nb+4.50+, and one Si4+ atom. In the eighth O2- site, O2- is bonded in a distorted tetrahedral geometry to three Na1+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+, one Nb+4.50+, and one Si4+ atom. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one Ti4+, and one Si4+ atom. F1- is bonded in a 4-coordinate geometry to three Na1+ and one Ti4+ atom.