DOI: 10.17188/1666677
title: Materials Data on NaCa2ZrSi2O9 by Materials Project

description: NaCa2ZrSi2O9 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded in a 5-coordinate geometry to six O atoms. There are a spread of Na–O bond distances ranging from 2.31–2.80 Å. In the second Na site, Na is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Na–O bond distances ranging from 2.34–2.90 Å. There are four inequivalent Ca sites. In the first Ca site, Ca is bonded to seven O atoms to form distorted CaO7 hexagonal pyramids that share a cornercorner with one ZrO6 octahedra, corners with three SiO4 tetrahedra, edges with two equivalent ZrO6 octahedra, and edges with two SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. There are a spread of Ca–O bond distances ranging from 2.29–2.77 Å. In the second Ca site, Ca is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of Ca–O bond distances ranging from 2.33–2.71 Å. In the third Ca site, Ca is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Ca–O bond distances ranging from 2.33–2.52 Å. In the fourth Ca site, Ca is bonded to six O atoms to form CaO6 octahedra that share a cornercorner with one ZrO6 octahedra, corners with five SiO4 tetrahedra, and an edgeedge with one ZrO6 octahedra. The corner-sharing octahedral tilt angles are 53°. There are a spread of Ca–O bond distances ranging from 2.33–2.45 Å. There are two inequivalent Zr sites. In the first Zr site, Zr is bonded to six O atoms to form ZrO6 octahedra that share a cornercorner with one ZrO6 octahedra, corners with five SiO4 tetrahedra, and edges with two equivalent CaO7 hexagonal pyramids. The corner-sharing octahedral tilt angles are 48°. There are a spread of Zr–O bond distances ranging from 2.03–2.27 Å. In the second Zr site, Zr is bonded to six O atoms to form ZrO6 octahedra that share a cornercorner with one CaO7 hexagonal pyramid, a cornercorner with one CaO6 octahedra, a cornercorner with one ZrO6 octahedra, corners with three SiO4 tetrahedra, and an edgeedge with one CaO6 octahedra. The corner-sharing octahedra tilt angles range from 48–53°. There are a spread of Zr–O bond distances ranging from 1.98–2.26 Å. There are four inequivalent Si sites. In the first Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one CaO7 hexagonal pyramid, a cornercorner with one CaO6 octahedra, a cornercorner with one ZrO6 octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one CaO7 hexagonal pyramid. The corner-sharing octahedra tilt angles range from 33–44°. There are a spread of Si–O bond distances ranging from 1.61–1.68 Å. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one CaO7 hexagonal pyramid, a cornercorner with one CaO6 octahedra, corners with two ZrO6 octahedra, and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 43–54°. There are a spread of Si–O bond distances ranging from 1.62–1.68 Å. In the third Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one CaO6 octahedra, corners with two equivalent ZrO6 octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one CaO7 hexagonal pyramid. The corner-sharing octahedra tilt angles range from 31–50°. There are a spread of Si–O bond distances ranging from 1.61–1.67 Å. In the fourth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one CaO7 hexagonal pyramid, corners with two equivalent CaO6 octahedra, corners with three ZrO6 octahedra, and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 40–67°. There are a spread of Si–O bond distances ranging from 1.61–1.67 Å. There are eighteen inequivalent O sites. In the first O site, O is bonded in a distorted bent 150 degrees geometry to one Na, one Ca, and two Si atoms. In the second O site, O is bonded in a distorted rectangular see-saw-like geometry to one Na, one Ca, one Zr, and one Si atom. In the third O site, O is bonded in a 3-coordinate geometry to two Ca and one Si atom. In the fourth O site, O is bonded in a 3-coordinate geometry to one Ca, one Zr, and one Si atom. In the fifth O site, O is bonded in a 4-coordinate geometry to one Na, two Ca, and one Si atom. In the sixth O site, O is bonded to two Na, one Ca, and one Zr atom to form distorted ONa2CaZr trigonal pyramids that share a cornercorner with one ONaCaZrSi trigonal pyramid and edges with two ONa2Ca2 tetrahedra. In the seventh O site, O is bonded in a 4-coordinate geometry to two Ca, one Zr, and one Si atom. In the eighth O site, O is bonded in a 2-coordinate geometry to one Na, one Ca, and two Si atoms. In the ninth O site, O is bonded in a 4-coordinate geometry to one Na, two Ca, and one Si atom. In the tenth O site, O is bonded in a distorted trigonal planar geometry to one Ca, one Zr, and one Si atom. In the eleventh O site, O is bonded to one Na, two Ca, and one Zr atom to form ONaCa2Zr tetrahedra that share corners with two equivalent ONa2Ca2 tetrahedra and edges with two ONaCaZrSi trigonal pyramids. In the twelfth O site, O is bonded in a distorted rectangular see-saw-like geometry to one Na, one Ca, and two Zr atoms. In the thirteenth O site, O is bonded in a 4-coordinate geometry to two Ca, one Zr, and one Si atom. In the fourteenth O site, O is bonded in a distorted trigonal planar geometry to one Ca, one Zr, and one Si atom. In the fifteenth O site, O is bonded in a 4-coordinate geometry to one Na, two Ca, and one Si atom. In the sixteenth O site, O is bonded in a 4-coordinate geometry to one Na, one Ca, one Zr, and one Si atom. In the seventeenth O site, O is bonded to one Na, one Ca, one Zr, and one Si atom to form distorted ONaCaZrSi trigonal pyramids that share corners with two equivalent ONa2Ca2 tetrahedra, a cornercorner with one ONa2CaZr trigonal pyramid, and an edgeedge with one ONaCa2Zr tetrahedra. In the eighteenth O site, O is bonded to two Na and two Ca atoms to form ONa2Ca2 tetrahedra that share corners with two equivalent ONaCa2Zr tetrahedra, corners with two equivalent ONaCaZrSi trigonal pyramids, and an edgeedge with one ONa2CaZr trigonal pyramid.