CRYSTAL STRUCTURE OF THE COMPOUNDS CuGa2S(Se)3I

Abstract

One of the directions for finding new materials is to complicate the component composition of the compounds. Therefore, the acquisition of new tetrachloride halogens and the study of their crystalline structure have become the object of this search. Ternary and quaternary chalcohenides and chalcоhalohenides with tetrahedral coordination cations are among the classes of compounds that are of great interest to researchers. The tetrahedral compounds of the composition AB2X3Y are formed in the systems AY – B 2 X 3 (where A – Cu, Ag; B – In; X – S, Se, Te; Y – Cl, Br, I). Our attention was focused on the compounds where A is Cu, B is Ga; X is S, Se; Y is I). By the X-ray phase analysis method, the existence of new quaternary compounds CuGa 2 S 3 I, CuGa 2 Se 3 I have been established and their crystal structures have been studied by the powder method. Compounds were synthesized by a direct single-temperature method from simple substances of copper, galium, sulfur, and freshly obtained copper (I) iodide. Sulfur had been previously cleaned by a twotime vacuum distillation method. The crystal structures of these compounds were determined from data sets obtained on the DRON 4-13 X-ray diffractometer (CuKα radiation, in the range of 10°≤2θ≤100°, scan step 0.05°, 20 sec. exposure at each point). The computation of the crystal structure of the quaternary compounds CuGa 2 S 3 I, CuGa 2 Se 3 I was performed using WinCSD software package. Compounds CuGa2S3I, CuGa2Se3I have been indexed in tetragonal syngony, space group I-4 with cell parameters: a= 0.3311 (2) nm, c= 1.04411 (5) nm for the sulfur-containing compound, a= 0.55821 (3) nm, c= 1.0981 (2) nm for the selenium-containing compound. The unit cell contains 14 atoms. The coordinates of the atoms and the isotropic displacement parameters have satisfactory values. In the structures of the compounds, the galium atoms occupy two regular point positions (2a and 2c) and have tetrahedral environments [Ga 14 S(Se) 1 ], [Ga 24 S(Se) 1 ]. The positions of Ga 1 (2a) and Ga 2 (2c) are 80% filled. The statistical mixtures M1 (Cu + Ga) and M2 (Cu + Ga) occupy two regular point systems (2b and 2d) and are surrounded by the tetrahedra [M 14 S(Se) 1 ], [M 24 S(Se) 1 ]. The statistical mixtures M 1 (2b) and M 2 (2d) have the following composition: 50% Cu and 20% Ga, 30% of the position is not filled.