Ge5Te4Se is Caswellsilverite-like structured and crystallizes in the tetragonal I4/mmm space group. There are three inequivalent Ge sites. In the first Ge site, Ge(1) is bonded to one Te(1) and five equivalent Te(2) atoms to form GeTe6 octahedra that share  a cornercorner with one Ge(3)Te2Se4 octahedra,  a cornercorner with one Ge(2)Te5Se octahedra, corners with four equivalent Ge(1)Te6 octahedra, edges with four equivalent Ge(2)Te5Se octahedra, and edges with eight equivalent Ge(1)Te6 octahedra. The corner-sharing octahedra are not tilted. In the second Ge site, Ge(2) is bonded to one Te(2), four equivalent Te(1), and one Se(1) atom to form GeTe5Se octahedra that share  a cornercorner with one Ge(1)Te6 octahedra, corners with five equivalent Ge(2)Te5Se octahedra, edges with four equivalent Ge(3)Te2Se4 octahedra, edges with four equivalent Ge(2)Te5Se octahedra, and edges with four equivalent Ge(1)Te6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the third Ge site, Ge(3) is bonded to two Te(1,1) and four equivalent Se(1) atoms to form GeTe2Se4 octahedra that share corners with two equivalent Ge(1)Te6 octahedra, corners with four equivalent Ge(3)Te2Se4 octahedra, edges with four equivalent Ge(3)Te2Se4 octahedra, and edges with eight equivalent Ge(2)Te5Se octahedra. The corner-sharing octahedra are not tilted. There are three inequivalent Te sites. In the first Te site, Te(1) is bonded to one Ge(1), one Ge(3), and four equivalent Ge(2) atoms to form TeGe6 octahedra that share  a cornercorner with one Te(2)Ge6 octahedra, corners with five equivalent Te(1)Ge6 octahedra, edges with four equivalent Te(1)Ge6 octahedra, edges with four equivalent Te(2)Ge6 octahedra, and edges with four equivalent Se(1)Ge6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the second Te site, Te(2) is bonded to one Ge(2) and five equivalent Ge(1) atoms to form TeGe6 octahedra that share  a cornercorner with one Te(1)Ge6 octahedra,  a cornercorner with one Se(1)Ge6 octahedra, corners with four equivalent Te(2)Ge6 octahedra, edges with four equivalent Te(1)Ge6 octahedra, and edges with eight equivalent Te(2)Ge6 octahedra. The corner-sharing octahedra are not tilted. In the third Te site, Te(1) is bonded to one Ge(1), one Ge(3), and four equivalent Ge(2) atoms to form TeGe6 octahedra that share  a cornercorner with one Te(2)Ge6 octahedra; corners with five Te(1,1)Ge6 octahedra; edges with four equivalent Te(1)Ge6 octahedra; edges with four equivalent Te(2)Ge6 octahedra; and edges with four equivalent Se(1)Ge6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. Se(1) is bonded to two equivalent Ge(2) and four equivalent Ge(3) atoms to form SeGe6 octahedra that share corners with two equivalent Te(2)Ge6 octahedra; corners with four equivalent Se(1)Ge6 octahedra; edges with four equivalent Se(1)Ge6 octahedra; and edges with eight Te(1,1)Ge6 octahedra. The corner-sharing octahedra are not tilted.
Ge5Te4Se is Caswellsilverite-like structured and crystallizes in the tetragonal I4/mmm space group. There are three inequivalent Ge sites. In the first Ge site, Ge(1) is bonded to one Te(1) and five equivalent Te(2) atoms to form GeTe6 octahedra that share  a cornercorner with one Ge(3)Te2Se4 octahedra,  a cornercorner with one Ge(2)Te5Se octahedra, corners with four equivalent Ge(1)Te6 octahedra, edges with four equivalent Ge(2)Te5Se octahedra, and edges with eight equivalent Ge(1)Te6 octahedra. The corner-sharing octahedra are not tilted. The Ge(1)-Te(1) bond length is 3.03 Å. There are four shorter (2.97 Å) and one longer (3.03 Å) Ge(1)-Te(2) bond length. In the second Ge site, Ge(2) is bonded to one Te(2), four equivalent Te(1), and one Se(1) atom to form GeTe5Se octahedra that share  a cornercorner with one Ge(1)Te6 octahedra, corners with five equivalent Ge(2)Te5Se octahedra, edges with four equivalent Ge(3)Te2Se4 octahedra, edges with four equivalent Ge(2)Te5Se octahedra, and edges with four equivalent Ge(1)Te6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. The Ge(2)-Te(2) bond length is 3.05 Å. All Ge(2)-Te(1) bond lengths are 2.97 Å. The Ge(2)-Se(1) bond length is 2.99 Å. In the third Ge site, Ge(3) is bonded to two Te(1,1) and four equivalent Se(1) atoms to form GeTe2Se4 octahedra that share corners with two equivalent Ge(1)Te6 octahedra, corners with four equivalent Ge(3)Te2Se4 octahedra, edges with four equivalent Ge(3)Te2Se4 octahedra, and edges with eight equivalent Ge(2)Te5Se octahedra. The corner-sharing octahedra are not tilted. Both Ge(3)-Te(1,1) bond lengths are 3.02 Å. All Ge(3)-Se(1) bond lengths are 2.97 Å. There are three inequivalent Te sites. In the first Te site, Te(1) is bonded to one Ge(1), one Ge(3), and four equivalent Ge(2) atoms to form TeGe6 octahedra that share  a cornercorner with one Te(2)Ge6 octahedra, corners with five equivalent Te(1)Ge6 octahedra, edges with four equivalent Te(1)Ge6 octahedra, edges with four equivalent Te(2)Ge6 octahedra, and edges with four equivalent Se(1)Ge6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the second Te site, Te(2) is bonded to one Ge(2) and five equivalent Ge(1) atoms to form TeGe6 octahedra that share  a cornercorner with one Te(1)Ge6 octahedra,  a cornercorner with one Se(1)Ge6 octahedra, corners with four equivalent Te(2)Ge6 octahedra, edges with four equivalent Te(1)Ge6 octahedra, and edges with eight equivalent Te(2)Ge6 octahedra. The corner-sharing octahedra are not tilted. In the third Te site, Te(1) is bonded to one Ge(1), one Ge(3), and four equivalent Ge(2) atoms to form TeGe6 octahedra that share  a cornercorner with one Te(2)Ge6 octahedra; corners with five Te(1,1)Ge6 octahedra; edges with four equivalent Te(1)Ge6 octahedra; edges with four equivalent Te(2)Ge6 octahedra; and edges with four equivalent Se(1)Ge6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. The Te(1)-Ge(1) bond length is 3.03 Å. All Te(1)-Ge(2) bond lengths are 2.97 Å. Se(1) is bonded to two equivalent Ge(2) and four equivalent Ge(3) atoms to form SeGe6 octahedra that share corners with two equivalent Te(2)Ge6 octahedra; corners with four equivalent Se(1)Ge6 octahedra; edges with four equivalent Se(1)Ge6 octahedra; and edges with eight Te(1,1)Ge6 octahedra. The corner-sharing octahedra are not tilted.