DOE OSTI2020
TlBiSe2 is Caswellsilverite-like structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are four inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded to six Se2- atoms to form distorted TlSe6 octahedra that share a cornercorner with one BiSe6 octahedra, corners with five TlSe6 octahedra, edges with four equivalent BiSe6 octahedra, and edges with eight TlSe6 octahedra. The corner-sharing octahedra tilt angles range from 0–16°. There are a spread of Tl–Se bond distances ranging from 2.87–3.48 Å. In the second Tl1+ site, Tl1+ is bonded to six Se2- atoms to form TlSe6 octahedra that share a cornercorner with one BiSe6 octahedra, corners with five TlSe6 octahedra, and edges with twelve TlSe6 octahedra. The corner-sharing octahedra tilt angles range from 0–5°. There are a spread of Tl–Se bond distances ranging from 2.91–3.44 Å. In the third Tl1+ site, Tl1+ is bonded to six Se2- atoms to form a mixture of corner and edge-sharing TlSe6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are a spread of Tl–Se bond distances ranging from 3.07–3.11 Å. In the fourth Tl1+ site, Tl1+ is bonded to six Se2- atoms to form a mixture of corner and edge-sharing TlSe6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (3.09 Å) and two longer (3.14 Å) Tl–Se bond lengths. There are five inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded to six Se2- atoms to form distorted BiSe6 octahedra that share a cornercorner with one TlSe6 octahedra, corners with five BiSe6 octahedra, edges with four equivalent TlSe6 octahedra, and edges with eight BiSe6 octahedra. The corner-sharing octahedra tilt angles range from 0–16°. There are a spread of Bi–Se bond distances ranging from 2.62–3.48 Å. In the second Bi3+ site, Bi3+ is bonded to six Se2- atoms to form BiSe6 octahedra that share a cornercorner with one TlSe6 octahedra, corners with five BiSe6 octahedra, and edges with twelve BiSe6 octahedra. The corner-sharing octahedra tilt angles range from 0–8°. There are a spread of Bi–Se bond distances ranging from 2.84–3.20 Å. In the third Bi3+ site, Bi3+ is bonded to six Se2- atoms to form a mixture of corner and edge-sharing BiSe6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are a spread of Bi–Se bond distances ranging from 2.89–3.13 Å. In the fourth Bi3+ site, Bi3+ is bonded to six Se2- atoms to form a mixture of corner and edge-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (3.02 Å) and four longer (3.09 Å) Bi–Se bond lengths. In the fifth Bi3+ site, Bi3+ is bonded to six Se2- atoms to form a mixture of corner and edge-sharing BiSe6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are a spread of Bi–Se bond distances ranging from 2.89–3.13 Å. There are eight inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to six Bi3+ atoms to form SeBi6 octahedra that share corners with six SeBi6 octahedra and edges with twelve SeTlBi5 octahedra. The corner-sharing octahedra tilt angles range from 0–8°. In the second Se2- site, Se2- is bonded to six Bi3+ atoms to form SeBi6 octahedra that share corners with six SeTlBi5 octahedra and edges with twelve SeBi6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. In the third Se2- site, Se2- is bonded to six Bi3+ atoms to form a mixture of corner and edge-sharing SeBi6 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourth Se2- site, Se2- is bonded to one Tl1+ and five Bi3+ atoms to form a mixture of corner and edge-sharing SeTlBi5 octahedra. The corner-sharing octahedra tilt angles range from 0–16°. In the fifth Se2- site, Se2- is bonded to five Tl1+ and one Bi3+ atom to form distorted SeTl5Bi octahedra that share corners with six SeTl5Bi octahedra and edges with twelve SeTlBi5 octahedra. The corner-sharing octahedra tilt angles range from 0–16°. In the sixth Se2- site, Se2- is bonded to six Tl1+ atoms to form SeTl6 octahedra that share corners with six SeTlBi5 octahedra and edges with twelve SeTl5Bi octahedra. The corner-sharing octahedra tilt angles range from 0–5°. In the seventh Se2- site, Se2- is bonded to six Tl1+ atoms to form SeTl6 octahedra that share corners with six SeTl5Bi octahedra and edges with twelve SeTl6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the eighth Se2- site, Se2- is bonded to six Tl1+ atoms to form a mixture of corner and edge-sharing SeTl6 octahedra. The corner-sharing octahedral tilt angles are 0°.