NaLa2Se3 is Caswellsilverite-like structured and crystallizes in the trigonal P-3m1 space group. Na(1) is bonded to six equivalent Se(1) atoms to form NaSe6 octahedra that share corners with six equivalent La(1)Se6 octahedra, edges with six equivalent Na(1)Se6 octahedra, and edges with six equivalent La(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 2°. La(1) is bonded to three equivalent Se(1) and three equivalent Se(2) atoms to form LaSe6 octahedra that share corners with three equivalent Na(1)Se6 octahedra, corners with three equivalent La(1)Se6 octahedra, edges with three equivalent Na(1)Se6 octahedra, and edges with nine equivalent La(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to three equivalent Na(1) and three equivalent La(1) atoms to form SeNa3La3 octahedra that share corners with three equivalent Se(2)La6 octahedra, corners with three equivalent Se(1)Na3La3 octahedra, edges with three equivalent Se(2)La6 octahedra, and edges with nine equivalent Se(1)Na3La3 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the second Se site, Se(2) is bonded to six equivalent La(1) atoms to form SeLa6 octahedra that share corners with six equivalent Se(1)Na3La3 octahedra, edges with six equivalent Se(2)La6 octahedra, and edges with six equivalent Se(1)Na3La3 octahedra. The corner-sharing octahedral tilt angles are 2°.
NaLa2Se3 is Caswellsilverite-like structured and crystallizes in the trigonal P-3m1 space group. Na(1) is bonded to six equivalent Se(1) atoms to form NaSe6 octahedra that share corners with six equivalent La(1)Se6 octahedra, edges with six equivalent Na(1)Se6 octahedra, and edges with six equivalent La(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 2°. All Na(1)-Se(1) bond lengths are 3.08 Å. La(1) is bonded to three equivalent Se(1) and three equivalent Se(2) atoms to form LaSe6 octahedra that share corners with three equivalent Na(1)Se6 octahedra, corners with three equivalent La(1)Se6 octahedra, edges with three equivalent Na(1)Se6 octahedra, and edges with nine equivalent La(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. All La(1)-Se(1) bond lengths are 3.00 Å. All La(1)-Se(2) bond lengths are 3.08 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to three equivalent Na(1) and three equivalent La(1) atoms to form SeNa3La3 octahedra that share corners with three equivalent Se(2)La6 octahedra, corners with three equivalent Se(1)Na3La3 octahedra, edges with three equivalent Se(2)La6 octahedra, and edges with nine equivalent Se(1)Na3La3 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the second Se site, Se(2) is bonded to six equivalent La(1) atoms to form SeLa6 octahedra that share corners with six equivalent Se(1)Na3La3 octahedra, edges with six equivalent Se(2)La6 octahedra, and edges with six equivalent Se(1)Na3La3 octahedra. The corner-sharing octahedral tilt angles are 2°.