SFEr is Matlockite structured and crystallizes in the tetragonal P4/nmm space group. Er(1) is bonded in a 9-coordinate geometry to five equivalent S(1) and four equivalent F(1) atoms. S(1) is bonded to five equivalent Er(1) atoms to form distorted SEr5 trigonal bipyramids that share corners with twelve equivalent F(1)Er4 tetrahedra, corners with four equivalent S(1)Er5 trigonal bipyramids, edges with four equivalent F(1)Er4 tetrahedra, and edges with eight equivalent S(1)Er5 trigonal bipyramids. F(1) is bonded to four equivalent Er(1) atoms to form FEr4 tetrahedra that share corners with four equivalent F(1)Er4 tetrahedra, corners with twelve equivalent S(1)Er5 trigonal bipyramids, edges with four equivalent F(1)Er4 tetrahedra, and edges with four equivalent S(1)Er5 trigonal bipyramids.
SFEr is Matlockite structured and crystallizes in the tetragonal P4/nmm space group. Er(1) is bonded in a 9-coordinate geometry to five equivalent S(1) and four equivalent F(1) atoms. There are four shorter (2.77 Å) and one longer (2.83 Å) Er(1)-S(1) bond length. All Er(1)-F(1) bond lengths are 2.41 Å. S(1) is bonded to five equivalent Er(1) atoms to form distorted SEr5 trigonal bipyramids that share corners with twelve equivalent F(1)Er4 tetrahedra, corners with four equivalent S(1)Er5 trigonal bipyramids, edges with four equivalent F(1)Er4 tetrahedra, and edges with eight equivalent S(1)Er5 trigonal bipyramids. F(1) is bonded to four equivalent Er(1) atoms to form FEr4 tetrahedra that share corners with four equivalent F(1)Er4 tetrahedra, corners with twelve equivalent S(1)Er5 trigonal bipyramids, edges with four equivalent F(1)Er4 tetrahedra, and edges with four equivalent S(1)Er5 trigonal bipyramids.