EuGd2S4 crystallizes in the tetragonal I-42d space group. Gd(1) is bonded to eight equivalent S(1) atoms to form distorted GdS8 hexagonal bipyramids that share corners with four equivalent Gd(1)S8 hexagonal bipyramids, corners with four equivalent Eu(1)S8 hexagonal bipyramids, edges with four equivalent Gd(1)S8 hexagonal bipyramids, faces with four equivalent Gd(1)S8 hexagonal bipyramids, and faces with four equivalent Eu(1)S8 hexagonal bipyramids. Eu(1) is bonded to eight equivalent S(1) atoms to form distorted EuS8 hexagonal bipyramids that share corners with eight equivalent Gd(1)S8 hexagonal bipyramids, edges with four equivalent Eu(1)S8 hexagonal bipyramids, and faces with eight equivalent Gd(1)S8 hexagonal bipyramids. S(1) is bonded to four equivalent Gd(1) and two equivalent Eu(1) atoms to form a mixture of distorted edge, corner, and face-sharing SEu2Gd4 octahedra. The corner-sharing octahedral tilt angles range from 17-50°.
EuGd2S4 crystallizes in the tetragonal I-42d space group. Gd(1) is bonded to eight equivalent S(1) atoms to form distorted GdS8 hexagonal bipyramids that share corners with four equivalent Gd(1)S8 hexagonal bipyramids, corners with four equivalent Eu(1)S8 hexagonal bipyramids, edges with four equivalent Gd(1)S8 hexagonal bipyramids, faces with four equivalent Gd(1)S8 hexagonal bipyramids, and faces with four equivalent Eu(1)S8 hexagonal bipyramids. There are a spread of Gd(1)-S(1) bond distances ranging from 2.78-3.07 Å. Eu(1) is bonded to eight equivalent S(1) atoms to form distorted EuS8 hexagonal bipyramids that share corners with eight equivalent Gd(1)S8 hexagonal bipyramids, edges with four equivalent Eu(1)S8 hexagonal bipyramids, and faces with eight equivalent Gd(1)S8 hexagonal bipyramids. There are four shorter (2.89 Å) and four longer (3.08 Å) Eu(1)-S(1) bond lengths. S(1) is bonded to four equivalent Gd(1) and two equivalent Eu(1) atoms to form a mixture of distorted edge, corner, and face-sharing SEu2Gd4 octahedra. The corner-sharing octahedral tilt angles range from 17-50°.