Superstructures in cubic AIIBVI crystals heavily doped with Ni and V ions

Specific features of the crystal structure of bulk sphalerite-type Zn_0.9Ni_0.1S, Zn_0.9V_0.1Se, and Zn_0.997Ni_0.003Te crystals have been investigated in detail by thermal-neutron diffraction at room temperature. Fine effects (indicative of the existence of distortion microdomains, nucleation of long- and short-wavelength modulations, and tendencies toward local lowering of the symmetry based on the initial cubic structure) can be observed in the obtained scattering patterns. Various states preceding the fcc ? hcp phase transition have been revealed in these crystals. They depend on the elemental composition and are formed upon the reaction of the initial lattice to perturbations induced by foreign ions with an incomplete 3d shell.