Materials Data on Na2Ca2(SiO3)3 by Materials Project

Abstract

Na2Ca2Si3O9 crystallizes in the trigonal R3m 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 eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.59–2.90 Å. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six equivalent SiO4 tetrahedra and a faceface with one CaO6 octahedra. There are three shorter (2.44 Å) and three longer (2.46 Å) Na–O bond lengths. There are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.26–2.99 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six SiO4 tetrahedra and a faceface with one NaO6 octahedra. There are three shorter (2.29 Å) and three longer (2.35 Å) Ca–O bond lengths. 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 CaO6 octahedra, corners with two equivalent NaO6 octahedra, and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 39–48°. There are a spread of Si–O bond distances ranging from 1.60–1.68 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one CaO6 octahedra and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 48°. There are a spread of Si–O bond distances ranging from 1.60–1.67 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to three Na1+, one Ca2+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one Ca2+, and one Si4+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, three Ca2+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to three Ca2+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Na1+, one Ca2+, and two Si4+ atoms.