DOI: 10.17188/1680195
title: Materials Data on NaCaTiFe3O8 by Materials Project

description: NaCaTiFe3O8 crystallizes in the orthorhombic Pmn2_1 space group. The structure is three-dimensional. Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.43–2.63 Å. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.38–2.59 Å. Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with four FeO6 octahedra, edges with two equivalent TiO6 octahedra, and edges with two equivalent FeO6 octahedra. The corner-sharing octahedra tilt angles range from 49–55°. There are a spread of Ti–O bond distances ranging from 1.93–2.07 Å. There are three inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent TiO6 octahedra, corners with two equivalent FeO6 octahedra, and edges with four FeO6 octahedra. The corner-sharing octahedra tilt angles range from 49–55°. There are a spread of Fe–O bond distances ranging from 2.01–2.10 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent TiO6 octahedra, corners with two equivalent FeO6 octahedra, and edges with four FeO6 octahedra. The corner-sharing octahedra tilt angles range from 49–59°. There are a spread of Fe–O bond distances ranging from 2.01–2.13 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four FeO6 octahedra, edges with two equivalent TiO6 octahedra, and edges with two equivalent FeO6 octahedra. The corner-sharing octahedra tilt angles range from 49–59°. There are a spread of Fe–O bond distances ranging from 1.99–2.11 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Na1+, two equivalent Ti4+, and one Fe3+ atom to form distorted ONa2Ti2Fe square pyramids that share corners with two equivalent ONa2Fe3 trigonal bipyramids, edges with four ONa2Ti2Fe square pyramids, and an edgeedge with one ONa2Fe3 trigonal bipyramid. In the second O2- site, O2- is bonded to two equivalent Ca2+, one Ti4+, and two equivalent Fe3+ atoms to form distorted OCa2TiFe2 square pyramids that share corners with two equivalent OCa2Fe3 trigonal bipyramids, edges with four ONa2Ti2Fe square pyramids, and an edgeedge with one OCa2Fe3 trigonal bipyramid. In the third O2- site, O2- is bonded in a 5-coordinate geometry to one Na1+, one Ca2+, two equivalent Ti4+, and one Fe3+ atom. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to one Na1+, one Ca2+, and three Fe3+ atoms. In the fifth O2- site, O2- is bonded to two equivalent Na1+ and three Fe3+ atoms to form distorted ONa2Fe3 trigonal bipyramids that share corners with two equivalent ONa2Ti2Fe square pyramids, an edgeedge with one ONa2Ti2Fe square pyramid, and edges with four ONa2Fe3 trigonal bipyramids. In the sixth O2- site, O2- is bonded to two equivalent Ca2+ and three Fe3+ atoms to form distorted OCa2Fe3 trigonal bipyramids that share corners with two equivalent OCa2TiFe2 square pyramids, an edgeedge with one OCa2TiFe2 square pyramid, and edges with four ONa2Fe3 trigonal bipyramids. In the seventh O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Na1+, one Ti4+, and two equivalent Fe3+ atoms. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Ca2+ and three Fe3+ atoms.