Materials Data on Er(FeO2)2 by Materials Project
ErFe2O4 is Aluminum carbonitride-like structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Er3+ is bonded to six equivalent O2- atoms to form ErO6 octahedra that share corners with six equivalent FeO5 trigonal bipyramids and edges with six equivalent ErO6 octahedra. All Er–O bond lengths are 2.27 Å. Fe+2.50+ is bonded to five O2- atoms to form FeO5 trigonal bipyramids that share corners with three equivalent ErO6 octahedra, corners with six equivalent FeO5 trigonal bipyramids, and edges with three equivalent FeO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 62°. There are a spread of Fe–O bond distances ranging from 1.99–2.16 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Fe+2.50+ atoms to form OFe4 trigonal pyramids that share corners with four equivalent OEr3Fe tetrahedra, corners with six equivalent OFe4 trigonal pyramids, and edges with three equivalent OFe4 trigonal pyramids. In the second O2- site, O2- is bonded to three equivalent Er3+ and one Fe+2.50+ atom to form OEr3Fe tetrahedra that share corners with nine equivalent OEr3Fe tetrahedra, corners with four equivalent OFe4 trigonal pyramids, and edges with three equivalent OEr3Fe tetrahedra.