Influence of Isomorphic Atom Substitution on Lattice Anisotropy of Thallium Dichalcogenide Layered Mixed Crystals

Compositional variation of the lattice parameters of TlBX$\text{}_{2}$-type (B = Ga or In and X = S or Se) mixed crystals with monoclinic structure were studied by X-ray diffraction technique. The lattice anisotropy (c/b) of these mixed crystals changes linearly with substitution of the atoms located both at the centers and the vertices of the corresponding BX$\text{}_{4}$ tetrahedra. A brief survey of the important features of the effect of isomorphic atom substitution on the lattice anisotropy and the unit cell volume of TlBX$\text{}_{2}$-type mixed crystals with layered structure was presented.