On local lattice instabilities and polymorphism in the ZnS_xSe_1-x:M (M = 3d-ions) sphalerite bulk crystals from neutron scattering

The structure of solid solutions, or quasi-binary compounds, cubic ZnSxSe1-x single crystals doped by 3d-ions M (M = V, Cr, Fe, Ni; M content was equal to 0.001; 0 <= x <= 1) was investigated by thermal neutron diffraction. The revealed diffuse scattering effects illustrate the pronounced interplay between two the strongest destabilizing influences, which can coexist in the sphalerite crystal structure of II - VI compounds diluted by magnetic 3d-ions. Disturbance of the host crystal lattice going from doped Jahn-Teller 3d-ions leading to a tendency to form superstructures. The structure instabilities of the solid solution matrices came from high degree polymorphism being especially intrinsic for ZnS, can result in anomalous enlarging of shear atomic displacement amplitudes along the directions of minimum of interatomic distances corresponding to the <110> crystallographic directions.