Synthesis of hexagonal telluride Cusub(1-x)Agsub(1-y)Te and determination of its structure by the electron diffraction method

The work continues a series of investigations on electronographic study of structures and crystallochemical properties of binary and ternary semiconducting compounds in system A1-B6. The crystal structure of a disordered hexagonal compound with the composition Cusub(0.80)Agsub(0.96)Te obtained in thin films by the vacuum evaporation of the stoichiometric alloy CuAgTe has been determined by the electronography method. The parameters of the hexagonal lattice are the following: a=8.54+-0.01, c=21.7+-0.1 A. The structure has been determined on the basis of three-dimensional syntheses of the interatomic function and potential (ordinary and differential Fourier syntheses) by the method of successive approximations. In the elementary cell 35 independent atoms occupy one- and three-fold positions of the space group P31(Csub(3v)I). Two thirds of the copper atoms and two silver atom randomly occupy their positions with different probabilities. The total amount of positions parameters equals 54. There is a strong scattering of interatomic distances of this structure, as well as in other hexagonal copper tellurides. The Cusub(1-x)Agsub(1-y)Te complex both in structural and crystallochemical sense is close to double copper tellurides. But at the same time it has its own structure type, unlike the rhombic CuAgTe2 which crystallizes in the CuTe structural type