Structural aspects of adamantine like multinary chalcogenides

The present state of knowledge of structure, phase relations and metal ordering in 2(ZrX) x (CuBX 2 ) i-x (B = Ga, In and X = S, Se, Te) and Cu 2 Zn x Fe 1-x SnS 4 multinary compounds is discussed. The chemical disorder process in 2(ZnX) x (CuBX 2 ) 1 -x alloys leads to a phase separation, i.e. in a certain composition range (2-phase field) two phases, tetragonal domains and a cubic matrix, coexist. Its width depends on the three-valent cation only and is independent from the size of anion. In the subsolidus region of the 2(ZnX) x (CUBX 2 ) 1 -x system the stability range of tetragonal mixed crystals as well as the miscibility gap is decreasing, the stability range of cubic mixed crystals is increasing. The process of structural disorder in 2(ZnX) x (CUBX 2 ) 1-x as well as Cu 2 Fe 1-x Zn x SnS 4 alloys is connected to the cation substructure. In tetragonal 2(ZnX) x (CuInX 2 ) 1-x alloys a non-random Zn distribution on the both cation positions of the chalcopyrite-type structure was revealed, whereas a random distribution of Zn and Cu on two different sites of the kesterite type structure was obtained in Cu 2 ZnSnS 4 in contradiction to literature. The crossover from stannite (x=0) to kesterite (x= 1) in Cu 2 Fe 1-x Zn x SnS 4 is considered as a three-stage process of cation restructure involving Cu + , Zn 2+ and Fe 2+ , whereas Sn 4+ does not take part in this process. In tetragonal 2(ZnX) x (CUInX 2 ) 1-x alloys the anion displacement is decreasing with increasing ZnX content in CuInX 2 indicating a decreasing tetragonal distortion. Here the disorder process in the cation substructure and the displacement process in the anion substructure are coupled.