Fine features of the crystal structure of the semiconductor cubic single crystal Zn$_{0.9}$V$_{0.1}$Sе

Fine features of the crystal structure of the semiconductor cubic single crystal Zn$_{0.9}$V$_{0.1}$Sе grown by the chemical transport method have been investigated using thermal neutron diffraction at room temperature. It has been revealed that the neutron diffraction scans of the single crystal, in addition to intense Bragg reflections of the face-centered cubic (fcc) phase, contain a complex system of superstructure reflections. Based on the sphalerite structure, it has been found for the first time that there are clear tendencies toward a decrease in the symmetry and a superposition of short-wavelength and long-wavelength modulations, which are interpreted as a consequence of the perturbations caused by doping vanadium ions and the cooperative response of the matrix lattice to these perturbations. The results of the performed experiment have been compared with the previously obtained data for the Zn$_{0.9}$Ni$_{0.1}$S crystal and interpreted as a manifestation of the pre-transition state to a reconstructive phase transition from the cubic phase to the hexagonal phase, which is accompanied by the aforementioned tendencies in the transformation of the structure.