Y4AsSe3 is Caswellsilverite-like structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to one As(1), one Se(2), and four equivalent Se(1) atoms to form YAsSe5 octahedra that share corners with six equivalent Y(1)AsSe5 octahedra, edges with four equivalent Y(1)AsSe5 octahedra, and edges with eight equivalent Y(2)As2Se4 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the second Y site, Y(2) is bonded to two equivalent As(1), two equivalent Se(1), and two equivalent Se(2) atoms to form YAs2Se4 octahedra that share corners with six equivalent Y(2)As2Se4 octahedra, edges with four equivalent Y(2)As2Se4 octahedra, and edges with eight equivalent Y(1)AsSe5 octahedra. The corner-sharing octahedra are not tilted. There are two inequivalent As sites. In the first As site, As(1) is bonded to two equivalent Y(1) and four equivalent Y(2) atoms to form AsY6 octahedra that share corners with two equivalent Se(2)Y6 octahedra, corners with four equivalent As(1)Y6 octahedra, edges with four equivalent Se(2)Y6 octahedra, and edges with eight equivalent Se(1)Y6 octahedra. The corner-sharing octahedra are not tilted. In the second As site, As(1) is bonded to two equivalent Y(1) and four equivalent Y(2) atoms to form AsY6 octahedra that share corners with two equivalent Se(2)Y6 octahedra, corners with four equivalent As(1)Y6 octahedra, edges with four equivalent Se(2)Y6 octahedra, and edges with eight equivalent Se(1)Y6 octahedra. The corner-sharing octahedra are not tilted. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent Y(2) and four equivalent Y(1) atoms to form SeY6 octahedra that share corners with six equivalent Se(1)Y6 octahedra; edges with four As(1,1)Y6 octahedra; edges with four equivalent Se(1)Y6 octahedra; and edges with four equivalent Se(2)Y6 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the second Se site, Se(2) is bonded to two equivalent Y(1) and four equivalent Y(2) atoms to form SeY6 octahedra that share corners with two equivalent As(1)Y6 octahedra, corners with four equivalent Se(2)Y6 octahedra, edges with four equivalent As(1)Y6 octahedra, and edges with eight equivalent Se(1)Y6 octahedra. The corner-sharing octahedra are not tilted.
Y4AsSe3 is Caswellsilverite-like structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to one As(1), one Se(2), and four equivalent Se(1) atoms to form YAsSe5 octahedra that share corners with six equivalent Y(1)AsSe5 octahedra, edges with four equivalent Y(1)AsSe5 octahedra, and edges with eight equivalent Y(2)As2Se4 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. The Y(1)-As(1) bond length is 2.80 Å. The Y(1)-Se(2) bond length is 2.99 Å. All Y(1)-Se(1) bond lengths are 2.89 Å. In the second Y site, Y(2) is bonded to two equivalent As(1), two equivalent Se(1), and two equivalent Se(2) atoms to form YAs2Se4 octahedra that share corners with six equivalent Y(2)As2Se4 octahedra, edges with four equivalent Y(2)As2Se4 octahedra, and edges with eight equivalent Y(1)AsSe5 octahedra. The corner-sharing octahedra are not tilted. Both Y(2)-As(1) bond lengths are 2.89 Å. Both Y(2)-Se(1) bond lengths are 2.90 Å. Both Y(2)-Se(2) bond lengths are 2.89 Å. There are two inequivalent As sites. In the first As site, As(1) is bonded to two equivalent Y(1) and four equivalent Y(2) atoms to form AsY6 octahedra that share corners with two equivalent Se(2)Y6 octahedra, corners with four equivalent As(1)Y6 octahedra, edges with four equivalent Se(2)Y6 octahedra, and edges with eight equivalent Se(1)Y6 octahedra. The corner-sharing octahedra are not tilted. In the second As site, As(1) is bonded to two equivalent Y(1) and four equivalent Y(2) atoms to form AsY6 octahedra that share corners with two equivalent Se(2)Y6 octahedra, corners with four equivalent As(1)Y6 octahedra, edges with four equivalent Se(2)Y6 octahedra, and edges with eight equivalent Se(1)Y6 octahedra. The corner-sharing octahedra are not tilted. Both As(1)-Y(1) bond lengths are 2.80 Å. All As(1)-Y(2) bond lengths are 2.89 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent Y(2) and four equivalent Y(1) atoms to form SeY6 octahedra that share corners with six equivalent Se(1)Y6 octahedra; edges with four As(1,1)Y6 octahedra; edges with four equivalent Se(1)Y6 octahedra; and edges with four equivalent Se(2)Y6 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the second Se site, Se(2) is bonded to two equivalent Y(1) and four equivalent Y(2) atoms to form SeY6 octahedra that share corners with two equivalent As(1)Y6 octahedra, corners with four equivalent Se(2)Y6 octahedra, edges with four equivalent As(1)Y6 octahedra, and edges with eight equivalent Se(1)Y6 octahedra. The corner-sharing octahedra are not tilted.