Model of Structural Ordering of Vacancies and Formation of a Family of Ternary Compounds in I–III–VI Systems

A characteristic feature of A^I–B^III–C^VI ternary chalcogenide compounds, which has a significant effect on the possibility of controlling the functional properties of materials based on them, is a strong tendency to stoichiometry deviation. The existence of ordered vacancy compounds in nanocrystals of the A^I–B^III–C^VI system was substantiated using the triangulation method (N.A. Goryunova’s method for predicting the composition of diamond-like semiconductors). Taking into account the assumption of the formation of electrically neutral defect complexes consisting of a vacancy in the position of the group I atom \(2[0]_{{\text{I}}}^{{ - 1}}\) and a doubly ionized antistructural defect \({\text{In}}_{{\text{I}}}^{{ + 2}}\) vacancies are presented as a pseudo-element of the “zero group”, while the system is considered from the point of view of the concentration tetrahedron so that the triangulation operations are transformed into tetrahedration operations. In the presence of such a “virtual” element, instead of a single stoichiometric composition in the A^I–B^III–C^VI system, a set of ternary compounds with an ordered content of vacancies known from the literature is determined, corresponding to semiconductors with four bonds per individual atom.