ErFe2O4 is Aluminum carbonitride-like structured and crystallizes in the trigonal R-3m space group. Er(1) is bonded to six equivalent O(2) atoms to form distorted ErO6 octahedra that share corners with six equivalent Fe(1)O5 trigonal bipyramids and edges with six equivalent Er(1)O6 octahedra. Fe(1) is bonded to one O(2) and four equivalent O(1) atoms to form FeO5 trigonal bipyramids that share corners with three equivalent Er(1)O6 octahedra, corners with six equivalent Fe(1)O5 trigonal bipyramids, and edges with three equivalent Fe(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 62°. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Fe(1) atoms to form OFe4 trigonal pyramids that share corners with four equivalent O(2)Er3Fe tetrahedra, corners with six equivalent O(1)Fe4 trigonal pyramids, and edges with three equivalent O(1)Fe4 trigonal pyramids. In the second O site, O(2) is bonded to three equivalent Er(1) and one Fe(1) atom to form OEr3Fe tetrahedra that share corners with nine equivalent O(2)Er3Fe tetrahedra, corners with four equivalent O(1)Fe4 trigonal pyramids, and edges with three equivalent O(2)Er3Fe tetrahedra.
ErFe2O4 is Aluminum carbonitride-like structured and crystallizes in the trigonal R-3m space group. Er(1) is bonded to six equivalent O(2) atoms to form distorted ErO6 octahedra that share corners with six equivalent Fe(1)O5 trigonal bipyramids and edges with six equivalent Er(1)O6 octahedra. All Er(1)-O(2) bond lengths are 2.27 Å. Fe(1) is bonded to one O(2) and four equivalent O(1) atoms to form FeO5 trigonal bipyramids that share corners with three equivalent Er(1)O6 octahedra, corners with six equivalent Fe(1)O5 trigonal bipyramids, and edges with three equivalent Fe(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 62°. The Fe(1)-O(2) bond length is 1.99 Å. There are three shorter (2.02 Å) and one longer (2.16 Å) Fe(1)-O(1) bond length. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Fe(1) atoms to form OFe4 trigonal pyramids that share corners with four equivalent O(2)Er3Fe tetrahedra, corners with six equivalent O(1)Fe4 trigonal pyramids, and edges with three equivalent O(1)Fe4 trigonal pyramids. In the second O site, O(2) is bonded to three equivalent Er(1) and one Fe(1) atom to form OEr3Fe tetrahedra that share corners with nine equivalent O(2)Er3Fe tetrahedra, corners with four equivalent O(1)Fe4 trigonal pyramids, and edges with three equivalent O(2)Er3Fe tetrahedra.