Crystal structures of the AgGa₂Se₃Cl and AgGa₂Te₃Cl compounds

Chem. Met. Alloys 13 (2020) 45-48

https://doi.org/10.30970/cma13.0399

Valentyna KOZAK, Inna IVASHCHENKO, Lubomyr GULAY, Ivan OLEKSEYUK

The crystal structures of the new quaternary compounds AgGa₂Se₃Cl and AgGa₂Te₃Cl have been studied by X-ray powder diffraction. An analysis of the diffraction diagrams indicated the tetragonal crystal system, structure type CuIn₂Te₃Cl (space group I-4) with the following unit-cell parameters: AgGa₂Se₃Cl, a = 0.59789(3) nm, c = 1.08592(7) nm; AgGa₂Te₃Cl, a = 0.63044(4) nm, c = 1.19562(8) nm. The Ga sites have tetrahedral surrounding and their positions (Wyckoff positions 2a and 2c) are filled to 80 %. The statistic mixtures M1, M2 (composition: 50 % Ag, 20 % Ga, 30 % vacancies) occupy two Wyckoff positions (2b and 2d) and center tetrahedra [M₁4Х] and [M₂4Х], where X = 75 % Se(Te), 25 % Cl.

Unit cell and coordination polyhedra of the Ag and Ga atoms in the crystal structures of the compounds AgGa₂Se(Te)₃Cl.

Keywords

Crystal structure / chalcogenides / X-ray powder diffraction