Preparation and investigation of (CuInSe 2 ) x (2ZnSe) 1-x and (CuInTe 2 ) x (2ZnTe) 1-x solid solution crystals The (CuInSe 2 ) x (2ZnSe) 1-x and (CuInTe 2 ) x (2ZnTe) 1-x solid solution crystals prepared by Bridgman method and chemical vapor transport have been studied. The nature of the crystalline phases, the local structure homogeneity and composition of these materials have been investigated by X-ray diffraction (XRD) and Electron Probe Microanalysis (EPMA) methods. The analysis revealed the presence of chalcopyrite-sphalerite phase transition between 0.6 ≤ X ≤ 0.7. Lattice constants, value of σ position parameter and bond length between atoms were also calculated. It was found that the lattice parameters exhibit a linear dependence versus composition. The transmission spectra of solid solution crystals in the region of the main absorption edge were studied. It was established that the optical band gap of these materials changes non-linearly with the X composition.