Materials Data on Na2Ca3(Si3O8)2 by Materials Project
Na2Ca3Si6O16 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.29–2.98 Å. In the second 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 2.32–2.84 Å. There are three inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share a cornercorner with one CaO5 square pyramid, corners with six SiO4 tetrahedra, and edges with four CaO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.33–2.64 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share a cornercorner with one CaO5 square pyramid, corners with six SiO4 tetrahedra, and edges with four CaO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.32–2.57 Å. In the third Ca2+ site, Ca2+ is bonded to five O2- atoms to form CaO5 square pyramids that share corners with two CaO6 octahedra, corners with five SiO4 tetrahedra, and an edgeedge with one CaO5 square pyramid. The corner-sharing octahedra tilt angles range from 68–72°. There are a spread of Ca–O bond distances ranging from 2.29–2.46 Å. There are six 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 CaO6 octahedra, a cornercorner with one CaO5 square pyramid, and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 74°. There are a spread of Si–O bond distances ranging from 1.61–1.65 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one CaO6 octahedra, a cornercorner with one CaO5 square pyramid, and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 72°. There are a spread of Si–O bond distances ranging from 1.61–1.65 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 corners with three SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–63°. There are a spread of Si–O bond distances ranging from 1.60–1.66 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three CaO6 octahedra, corners with two equivalent CaO5 square pyramids, and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–67°. There are a spread of Si–O bond distances ranging from 1.62–1.66 Å. In the fifth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two CaO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–60°. There are a spread of Si–O bond distances ranging from 1.60–1.66 Å. In the sixth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three CaO6 octahedra, a cornercorner with one CaO5 square pyramid, and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–65°. There are a spread of Si–O bond distances ranging from 1.61–1.67 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Na1+ and two Si4+ atoms. In the third O2- site, O2- is bonded to one Na1+, two Ca2+, and one Si4+ atom to form distorted corner-sharing ONaCa2Si tetrahedra. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Si4+ atom. In the fifth O2- site, O2- is bonded to one Na1+, two Ca2+, and one Si4+ atom to form distorted corner-sharing ONaCa2Si tetrahedra. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one Ca2+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+ and two Si4+ atoms. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+ and two Si4+ atoms. In the ninth O2- site, O2- is bonded in a trigonal planar geometry to one Na1+ and two Si4+ atoms. In the tenth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+ and two Si4+ atoms. In the eleventh O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Ca2+ and one Si4+ atom. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Si4+ atom. In the thirteenth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+ and two Si4+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ca2+ and one Si4+ atom. In the fifteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, two equivalent Ca2+, and one Si4+ atom. In the sixteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Na1+ and two Si4+ atoms.