Materials Data on NaCaFe(SiO3)4 by Materials Project

Abstract

NaCaFe(SiO3)4 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. Na is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Na–O bond distances ranging from 2.36–2.85 Å. Ca is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ca–O bond distances ranging from 2.29–2.85 Å. Fe is bonded to six O atoms to form FeO6 octahedra that share corners with six SiO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 1.95–2.09 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two equivalent FeO6 octahedra and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 32–50°. There are a spread of Si–O bond distances ranging from 1.62–1.69 Å. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one FeO6 octahedra and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 52°. There are a spread of Si–O bond distances ranging from 1.62–1.67 Å. There are six inequivalent O sites. In the first O site, O is bonded in a distorted T-shaped geometry to one Na, one Fe, and one Si atom. In the second O site, O is bonded in a water-like geometry to one Ca and one Si atom. In the third O site, O is bonded in a distorted trigonal planar geometry to one Ca, one Fe, and one Si atom. In the fourth O site, O is bonded in a distorted trigonal planar geometry to one Na, one Fe, and one Si atom. In the fifth O site, O is bonded in a distorted bent 150 degrees geometry to one Na, one Ca, and two Si atoms. In the sixth O site, O is bonded in a 2-coordinate geometry to one Na, one Ca, and two Si atoms.