DOE OSTI2020
LiGdSe2 is Caswellsilverite-like structured and crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Li1+ is bonded to six Se2- atoms to form LiSe6 octahedra that share corners with two equivalent GdSe6 octahedra, corners with four equivalent LiSe6 octahedra, edges with four equivalent LiSe6 octahedra, and edges with eight equivalent GdSe6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are four shorter (2.88 Å) and two longer (2.91 Å) Li–Se bond lengths. Gd3+ is bonded to six Se2- atoms to form GdSe6 octahedra that share corners with two equivalent LiSe6 octahedra, corners with four equivalent GdSe6 octahedra, edges with four equivalent GdSe6 octahedra, and edges with eight equivalent LiSe6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are four shorter (2.88 Å) and two longer (2.89 Å) Gd–Se bond lengths. There are five inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three equivalent Li1+ and three equivalent Gd3+ atoms to form a mixture of corner and edge-sharing SeLi3Gd3 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the second Se2- site, Se2- is bonded to three equivalent Li1+ and three equivalent Gd3+ atoms to form a mixture of corner and edge-sharing SeLi3Gd3 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are two shorter (2.88 Å) and one longer (2.89 Å) Se–Gd bond lengths. In the third Se2- site, Se2- is bonded to three equivalent Li1+ and three equivalent Gd3+ atoms to form a mixture of corner and edge-sharing SeLi3Gd3 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the fourth Se2- site, Se2- is bonded to three equivalent Li1+ and three equivalent Gd3+ atoms to form a mixture of corner and edge-sharing SeLi3Gd3 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are two shorter (2.88 Å) and one longer (2.91 Å) Se–Li bond lengths. There are two shorter (2.88 Å) and one longer (2.89 Å) Se–Gd bond lengths. In the fifth Se2- site, Se2- is bonded to three equivalent Li1+ and three equivalent Gd3+ atoms to form a mixture of corner and edge-sharing SeLi3Gd3 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are two shorter (2.88 Å) and one longer (2.89 Å) Se–Gd bond lengths.