DOI: 10.17188/1266764
title: Materials Data on Ca7NbSi4O17F by Materials Project

description: Ca7NbSi4O17F crystallizes in the monoclinic Pc space group. The structure is three-dimensional. there are seven inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.35–2.70 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share a cornercorner with one NbO6 octahedra and corners with five SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 56°. There are a spread of Ca–O bond distances ranging from 2.30–2.46 Å. In the third Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to six O2- and one F1- atom. There are a spread of Ca–O bond distances ranging from 2.31–2.59 Å. The Ca–F bond length is 2.39 Å. In the fourth Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to six O2- and one F1- atom. There are a spread of Ca–O bond distances ranging from 2.27–2.76 Å. The Ca–F bond length is 2.40 Å. In the fifth Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to seven O2- and one F1- atom. There are a spread of Ca–O bond distances ranging from 2.32–2.93 Å. The Ca–F bond length is 2.33 Å. In the sixth Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to six O2- and one F1- atom. There are a spread of Ca–O bond distances ranging from 2.32–2.88 Å. The Ca–F bond length is 2.47 Å. In the seventh Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share a cornercorner with one NbO6 octahedra, corners with five SiO4 tetrahedra, and an edgeedge with one NbO6 octahedra. The corner-sharing octahedral tilt angles are 45°. There are a spread of Ca–O bond distances ranging from 2.31–2.50 Å. Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two CaO6 octahedra, corners with three SiO4 tetrahedra, and an edgeedge with one CaO6 octahedra. The corner-sharing octahedra tilt angles range from 45–56°. There are a spread of Nb–O bond distances ranging from 1.90–2.28 Å. There are four inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two CaO6 octahedra, corners with two equivalent NbO6 octahedra, and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–60°. There are a spread of Si–O bond distances ranging from 1.62–1.68 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one NbO6 octahedra, corners with three CaO6 octahedra, and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 41–68°. There are a spread of Si–O bond distances ranging from 1.62–1.67 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two CaO6 octahedra and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 36–41°. There is three shorter (1.63 Å) and one longer (1.68 Å) Si–O bond length. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three CaO6 octahedra and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 43–67°. There is three shorter (1.63 Å) and one longer (1.68 Å) Si–O bond length. There are seventeen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two Ca2+, one Nb5+, and one Si4+ atom. In the second O2- site, O2- is bonded to three Ca2+ and one Si4+ atom to form distorted OCa3Si tetrahedra that share a cornercorner with one OCa3Nb tetrahedra, corners with two equivalent FCa4 tetrahedra, and a cornercorner with one OCa3Nb trigonal pyramid. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Nb5+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two Ca2+, one Nb5+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to three Ca2+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to three Ca2+ and one Si4+ atom. In the eighth O2- site, O2- is bonded to three Ca2+ and one Si4+ atom to form distorted OCa3Si trigonal pyramids that share corners with two equivalent FCa4 tetrahedra, a cornercorner with one OCa3Nb trigonal pyramid, and an edgeedge with one OCa3Nb tetrahedra. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Si4+ atom. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Si4+ atom. In the eleventh O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Si4+ atom. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to two Ca2+ and one Si4+ atom. In the thirteenth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Nb5+ atom. In the fourteenth O2- site, O2- is bonded to three Ca2+ and one Nb5+ atom to form distorted OCa3Nb trigonal pyramids that share a cornercorner with one OCa3Si tetrahedra, a cornercorner with one OCa3Si trigonal pyramid, an edgeedge with one OCa3Nb tetrahedra, and an edgeedge with one FCa4 tetrahedra. In the fifteenth O2- site, O2- is bonded to three Ca2+ and one Nb5+ atom to form distorted OCa3Nb tetrahedra that share a cornercorner with one OCa3Si tetrahedra, corners with two equivalent FCa4 tetrahedra, and edges with two OCa3Nb trigonal pyramids. In the sixteenth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+ and two Si4+ atoms. In the seventeenth O2- site, O2- is bonded in a 2-coordinate geometry to two Ca2+ and two Si4+ atoms. F1- is bonded to four Ca2+ atoms to form distorted FCa4 tetrahedra that share corners with four OCa3Nb tetrahedra, corners with two equivalent OCa3Si trigonal pyramids, and an edgeedge with one OCa3Nb trigonal pyramid.