DOE OSTI2020
Ga7(CuSe4)3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are three inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded to four Se2- atoms to form CuSe4 tetrahedra that share corners with three CuSe4 tetrahedra and corners with nine GaSe4 tetrahedra. There are a spread of Cu–Se bond distances ranging from 2.40–2.44 Å. In the second Cu1+ site, Cu1+ is bonded to four Se2- atoms to form CuSe4 tetrahedra that share corners with four CuSe4 tetrahedra and corners with seven GaSe4 tetrahedra. There are a spread of Cu–Se bond distances ranging from 2.38–2.47 Å. In the third Cu1+ site, Cu1+ is bonded to four Se2- atoms to form CuSe4 tetrahedra that share corners with five CuSe4 tetrahedra and corners with seven GaSe4 tetrahedra. There are a spread of Cu–Se bond distances ranging from 2.37–2.43 Å. There are seven inequivalent Ga3+ sites. In the first Ga3+ site, Ga3+ is bonded to four Se2- atoms to form GaSe4 tetrahedra that share corners with two equivalent CuSe4 tetrahedra and corners with seven GaSe4 tetrahedra. There are a spread of Ga–Se bond distances ranging from 2.43–2.51 Å. In the second Ga3+ site, Ga3+ is bonded to four Se2- atoms to form GaSe4 tetrahedra that share corners with four CuSe4 tetrahedra and corners with seven GaSe4 tetrahedra. There are a spread of Ga–Se bond distances ranging from 2.42–2.51 Å. In the third Ga3+ site, Ga3+ is bonded to four Se2- atoms to form GaSe4 tetrahedra that share corners with two equivalent CuSe4 tetrahedra and corners with seven GaSe4 tetrahedra. There are a spread of Ga–Se bond distances ranging from 2.35–2.53 Å. In the fourth Ga3+ site, Ga3+ is bonded to four Se2- atoms to form GaSe4 tetrahedra that share a cornercorner with one CuSe4 tetrahedra and corners with seven GaSe4 tetrahedra. There are a spread of Ga–Se bond distances ranging from 2.33–2.52 Å. In the fifth Ga3+ site, Ga3+ is bonded to four Se2- atoms to form GaSe4 tetrahedra that share corners with three CuSe4 tetrahedra and corners with five GaSe4 tetrahedra. There are a spread of Ga–Se bond distances ranging from 2.39–2.53 Å. In the sixth Ga3+ site, Ga3+ is bonded to four Se2- atoms to form GaSe4 tetrahedra that share corners with four GaSe4 tetrahedra and corners with six CuSe4 tetrahedra. There are a spread of Ga–Se bond distances ranging from 2.42–2.51 Å. In the seventh Ga3+ site, Ga3+ is bonded to four Se2- atoms to form GaSe4 tetrahedra that share corners with five CuSe4 tetrahedra and corners with five GaSe4 tetrahedra. There are a spread of Ga–Se bond distances ranging from 2.37–2.58 Å. There are twelve inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to three Ga3+ atoms. In the second Se2- site, Se2- is bonded in a water-like geometry to two Ga3+ atoms. In the third Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to three Ga3+ atoms. In the fourth Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to three Ga3+ atoms. In the fifth Se2- site, Se2- is bonded to one Cu1+ and three Ga3+ atoms to form corner-sharing SeGa3Cu tetrahedra. In the sixth Se2- site, Se2- is bonded in a water-like geometry to two Ga3+ atoms. In the seventh Se2- site, Se2- is bonded to two Cu1+ and two equivalent Ga3+ atoms to form corner-sharing SeGa2Cu2 tetrahedra. In the eighth Se2- site, Se2- is bonded to one Cu1+ and three Ga3+ atoms to form corner-sharing SeGa3Cu tetrahedra. In the ninth Se2- site, Se2- is bonded to two equivalent Cu1+ and two Ga3+ atoms to form corner-sharing SeGa2Cu2 tetrahedra. In the tenth Se2- site, Se2- is bonded to two equivalent Cu1+ and two Ga3+ atoms to form corner-sharing SeGa2Cu2 tetrahedra. In the eleventh Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Cu1+ and two equivalent Ga3+ atoms. In the twelfth Se2- site, Se2- is bonded to three Cu1+ and one Ga3+ atom to form corner-sharing SeGaCu3 tetrahedra.