Crystal formation features in a series of chalcogenide structures with monovalent Tl. Ordered packing effect in Tl coordination

In order to determine the crystal- forming factors and reasons for irregular coordination of Tl+ cations the crystallographic analysis of the structure of AgTlTe (I), minerals vrbaite Hg3Tl4As8Sb2S20 (II) and gabrielite Tl2AgCu2As3S7 (III) is performed. For I and II the skeleton translational sublattices of all atoms in the structure with the determining contribution of Tl+ and anions are found; for II and III the cationic and anionic along with Tl+ sublattices, which form the structure, are found. The incorporation of cations into the Tl+ coordination environment is classified as a consequence of the structure-forming ordering of Tl cations and anions (S, Te) in one matrix, i.e. as the effect of their ordered packing.