EuSmSe2 is Caswellsilverite structured and crystallizes in the trigonal R-3m space group. Eu(1) is bonded to six equivalent Se(1) atoms to form EuSe6 octahedra that share corners with six equivalent Sm(1)Se6 octahedra, edges with six equivalent Eu(1)Se6 octahedra, and edges with six equivalent Sm(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 2°. Sm(1) is bonded to six equivalent Se(1) atoms to form SmSe6 octahedra that share corners with six equivalent Eu(1)Se6 octahedra, edges with six equivalent Eu(1)Se6 octahedra, and edges with six equivalent Sm(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 2°. Se(1) is bonded to three equivalent Eu(1) and three equivalent Sm(1) atoms to form a mixture of edge and corner-sharing SeSm3Eu3 octahedra. The corner-sharing octahedra are not tilted.
EuSmSe2 is Caswellsilverite structured and crystallizes in the trigonal R-3m space group. Eu(1) is bonded to six equivalent Se(1) atoms to form EuSe6 octahedra that share corners with six equivalent Sm(1)Se6 octahedra, edges with six equivalent Eu(1)Se6 octahedra, and edges with six equivalent Sm(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 2°. All Eu(1)-Se(1) bond lengths are 3.02 Å. Sm(1) is bonded to six equivalent Se(1) atoms to form SmSe6 octahedra that share corners with six equivalent Eu(1)Se6 octahedra, edges with six equivalent Eu(1)Se6 octahedra, and edges with six equivalent Sm(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 2°. All Sm(1)-Se(1) bond lengths are 2.96 Å. Se(1) is bonded to three equivalent Eu(1) and three equivalent Sm(1) atoms to form a mixture of edge and corner-sharing SeSm3Eu3 octahedra. The corner-sharing octahedra are not tilted.