DOI: 10.17188/1745805
title: Materials Data on Na2Ca4ZrNbSi4(O8F)2 by Materials Project

description: Na2Ca4ZrNbSi4(O8F)2 is Esseneite-derived structured and crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 8-coordinate geometry to six O2- and two F1- atoms. There are a spread of Na–O bond distances ranging from 2.33–3.00 Å. There are one shorter (2.23 Å) and one longer (2.45 Å) Na–F bond lengths. In the second Na1+ site, Na1+ is bonded in a 8-coordinate geometry to six O2- and two F1- atoms. There are a spread of Na–O bond distances ranging from 2.43–2.94 Å. There are one shorter (2.33 Å) and one longer (2.62 Å) Na–F bond lengths. There are four inequivalent Ca2+ sites. In the first 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 2.29–2.87 Å. The Ca–F bond length is 2.28 Å. In the second Ca2+ site, Ca2+ is bonded to five O2- and one F1- atom to form distorted CaO5F octahedra that share corners with five SiO4 tetrahedra, an edgeedge with one NbO5F octahedra, and edges with two equivalent CaO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.31–2.65 Å. The Ca–F bond length is 2.30 Å. In the third Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share a cornercorner with one NbO5F octahedra, corners with five SiO4 tetrahedra, an edgeedge with one NbO5F octahedra, and edges with two equivalent CaO5F octahedra. The corner-sharing octahedral tilt angles are 52°. There are a spread of Ca–O bond distances ranging from 2.32–2.54 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 2.33–2.76 Å. The Ca–F bond length is 2.29 Å. Zr3+ is bonded to six O2- atoms to form ZrO6 octahedra that share a cornercorner with one NbO5F octahedra and corners with five SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 47°. There are a spread of Zr–O bond distances ranging from 2.03–2.25 Å. Nb5+ is bonded to five O2- and one F1- atom to form NbO5F octahedra that share a cornercorner with one CaO6 octahedra, a cornercorner with one ZrO6 octahedra, corners with three SiO4 tetrahedra, and edges with two CaO5F octahedra. The corner-sharing octahedra tilt angles range from 47–52°. There are a spread of Nb–O bond distances ranging from 1.86–2.27 Å. The Nb–F bond length is 2.18 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 a cornercorner with one ZrO6 octahedra, corners with two CaO5F octahedra, and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–58°. 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 ZrO6 octahedra, corners with two equivalent NbO5F octahedra, corners with three CaO5F octahedra, and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–71°. All Si–O bond lengths are 1.64 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two CaO5F octahedra, corners with two equivalent ZrO6 octahedra, and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 27–62°. There are a spread of Si–O bond distances ranging from 1.62–1.67 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one ZrO6 octahedra, a cornercorner with one NbO5F octahedra, corners with three CaO5F octahedra, and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 36–65°. There are a spread of Si–O bond distances ranging from 1.62–1.66 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ca2+, one Zr3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two Ca2+, one Zr3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Ca2+, one Nb5+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Na1+, one Ca2+, and two Si4+ atoms. In the fifth O2- site, O2- is bonded to one Na1+, two Ca2+, and one Si4+ atom to form distorted ONaCa2Si trigonal pyramids that share corners with two equivalent FNa2Ca2 tetrahedra and an edgeedge with one ONaCa2Nb tetrahedra. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, two Ca2+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Na1+, one Ca2+, one Zr3+, and one Nb5+ atom. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Si4+ atom. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Ca2+, one Zr3+, and one Si4+ atom. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Zr3+, and one Si4+ atom. In the eleventh O2- site, O2- is bonded to one Na1+, two Ca2+, and one Si4+ atom to form distorted ONaCa2Si tetrahedra that share a cornercorner with one ONaCa2Nb tetrahedra and corners with two equivalent FNa2Ca2 tetrahedra. In the twelfth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Na1+, one Ca2+, and two Si4+ atoms. In the thirteenth O2- site, O2- is bonded to one Na1+, two Ca2+, and one Nb5+ atom to form distorted ONaCa2Nb tetrahedra that share a cornercorner with one ONaCa2Si tetrahedra, corners with two equivalent FNa2Ca2 tetrahedra, and an edgeedge with one ONaCa2Si trigonal pyramid. In the fourteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ca2+, one Zr3+, and one Si4+ atom. In the fifteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ca2+, one Nb5+, and one Si4+ atom. In the sixteenth O2- site, O2- is bonded in a 1-coordinate geometry to two Ca2+, one Nb5+, and one Si4+ atom. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded to two Na1+ and two Ca2+ atoms to form FNa2Ca2 tetrahedra that share corners with four ONaCa2Si tetrahedra and corners with two equivalent ONaCa2Si trigonal pyramids. In the second F1- site, F1- is bonded in a 4-coordinate geometry to two Na1+, one Ca2+, and one Nb5+ atom.