Sr4Se3S is Caswellsilverite-like structured and crystallizes in the trigonal R-3m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to three equivalent Se(1) and three equivalent Se(2) atoms to form SrSe6 octahedra that share corners with three equivalent Sr(2)Se3S3 octahedra, corners with three equivalent Sr(1)Se6 octahedra, edges with three equivalent Sr(2)Se3S3 octahedra, and edges with nine equivalent Sr(1)Se6 octahedra. The corner-sharing octahedra are not tilted. In the second Sr site, Sr(2) is bonded to three equivalent Se(1) and three equivalent S(1) atoms to form SrSe3S3 octahedra that share corners with three equivalent Sr(2)Se3S3 octahedra, corners with three equivalent Sr(1)Se6 octahedra, edges with three equivalent Sr(1)Se6 octahedra, and edges with nine equivalent Sr(2)Se3S3 octahedra. The corner-sharing octahedra are not tilted. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to three equivalent Sr(1) and three equivalent Sr(2) atoms to form SeSr6 octahedra that share corners with three equivalent Se(2)Sr6 octahedra, corners with three equivalent S(1)Sr6 octahedra, edges with three equivalent Se(2)Sr6 octahedra, edges with three equivalent S(1)Sr6 octahedra, and edges with six equivalent Se(1)Sr6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the second Se site, Se(2) is bonded to six equivalent Sr(1) atoms to form a mixture of edge and corner-sharing SeSr6 octahedra. The corner-sharing octahedra are not tilted. S(1) is bonded to six equivalent Sr(2) atoms to form SSr6 octahedra that share corners with six equivalent Se(1)Sr6 octahedra, edges with six equivalent Se(1)Sr6 octahedra, and edges with six equivalent S(1)Sr6 octahedra. The corner-sharing octahedral tilt angles are 2°.
Sr4Se3S is Caswellsilverite-like structured and crystallizes in the trigonal R-3m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to three equivalent Se(1) and three equivalent Se(2) atoms to form SrSe6 octahedra that share corners with three equivalent Sr(2)Se3S3 octahedra, corners with three equivalent Sr(1)Se6 octahedra, edges with three equivalent Sr(2)Se3S3 octahedra, and edges with nine equivalent Sr(1)Se6 octahedra. The corner-sharing octahedra are not tilted. All Sr(1)-Se(1) bond lengths are 3.13 Å. All Sr(1)-Se(2) bond lengths are 3.13 Å. In the second Sr site, Sr(2) is bonded to three equivalent Se(1) and three equivalent S(1) atoms to form SrSe3S3 octahedra that share corners with three equivalent Sr(2)Se3S3 octahedra, corners with three equivalent Sr(1)Se6 octahedra, edges with three equivalent Sr(1)Se6 octahedra, and edges with nine equivalent Sr(2)Se3S3 octahedra. The corner-sharing octahedra are not tilted. All Sr(2)-Se(1) bond lengths are 3.13 Å. All Sr(2)-S(1) bond lengths are 3.06 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to three equivalent Sr(1) and three equivalent Sr(2) atoms to form SeSr6 octahedra that share corners with three equivalent Se(2)Sr6 octahedra, corners with three equivalent S(1)Sr6 octahedra, edges with three equivalent Se(2)Sr6 octahedra, edges with three equivalent S(1)Sr6 octahedra, and edges with six equivalent Se(1)Sr6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the second Se site, Se(2) is bonded to six equivalent Sr(1) atoms to form a mixture of edge and corner-sharing SeSr6 octahedra. The corner-sharing octahedra are not tilted. S(1) is bonded to six equivalent Sr(2) atoms to form SSr6 octahedra that share corners with six equivalent Se(1)Sr6 octahedra, edges with six equivalent Se(1)Sr6 octahedra, and edges with six equivalent S(1)Sr6 octahedra. The corner-sharing octahedral tilt angles are 2°.