Phase relationships in the pseudo-binary 2(ZnTe)-CuInTe2 system

Subsolidus phase relationships in the 2(ZnTe)x(CuInTe2)1−x system were investigated by TEM experiments combined with EDX analysis. The samples were prepared by the solid-state reaction of the elements during long annealing times, followed by either quenching in ice-cold water, or by controlled cooling at different rates. Using the chemical compositions of single and coexisting phases at various temperatures, the boundaries of the two-phase region have been determined. At room temperature, the two-phase region extends from image to image. For image only mixed crystals with tetragonal structure exist. Between image and image alloys with the cubic structure are stable. The morphology of the tetragonal domains and their orientation relationship to the cubic matrix were determined by SAD, TEM and HRTEM experiments. The tetragonal phase embedded within the cubic matrix has a flat ellipsoidal shape, whose short axis coincides with the tetragonal c-axis. The three topotaxial orientation relationships between the tetragonal domains and the surrounding cubic matrix were found to be: [001]tetr.∥[100]cub., [001]tetr.∥[010]cub. and [001]tetr.∥[001]cub.. There is an indication that the nucleation starts from small regions displaying cation ordering according to the CuPt-type structure. Reaching the two-phase equilibrium, the tetragonal domains as well as the surrounding cubic phase are free of this cation ordering.