Atomic structure of Cd1 − x Zn x Te solid solution single crystals and structural prerequisites of their ferroelectricity

Precision X-ray structural investigation of Cd_{1 ? x} Zn _x Te single crystals (x = 0.04, 0.10, 0.21, 0.30, 0.40) is performed at temperatures below and above the ferroelectric phase transition. The regularities associated with the increase in the concentration of Zn atoms in solid solutions are revealed. It is established that the unit cell parameter of the crystals varies according to the Vegard law. The thermal parameters of Te and Zn atoms are strongly overestimated within the model of a sphalerite-type average structure. It is found that the positions of the Zn cations are split and the anion sublattice is disordered in such a way that the Te anions are predominantly displaced along the threefold axes. The Zn atoms can serve as off-center impurities. This phenomenon offers strong possibilities for manifesting the ferroelectric properties in the solid solutions under investigation.