Synthesis And Study On The Growth Mechanism Of Ⅰ-Ⅵ Compound Microcrystal With Complex Structure

Shape-control of inorganic nanomaterials has been a key issue in modern synthesis of materials and fabrication of nanodevices. This paper aimed to explore new chemical routes for the synthesis of inorganic semiconductor nanomaterials. By systematical adjusting the crucial factors in the solvothermal reaction system, we have succeeded in the synthesis of â…  -â…¥ metal chalcogenides with complex structures. The results can be summarized as follows:1. Well-defined concaved cuboctahedrons of CuS crystals have been successfully synthesized by a solvothermal reaction of Cu(NO₃)₂ and sulfur powder at 140℃ in ethylene glycol. Each CuS crystal is apparently "caved" with 14 highly symmetric cavities and is constructed by four identical hexagonal flakes while sharing the 24 edges in a dymaxion way. This kind of crystals with complex structures and high geometrical symmetry can also be called as "Escher" crystal. The results demonstrate that the branching growth process in solution can be precisely manipulated for the controlled growth of amazingly complex crystalline structures with high geometrical symmetry, which is not reflected in the primary crystal symmetry. Neither the use of Cu²⁺ sources with other anions nor the use of other sulfur sources leads to particles with similarly high definition, thus the anions of different Cu²⁺ sources and the release rate of S^2- ions from sulfur sources play a crucial role in the growth process of the crystals. Other factors such as reaction temperature, solvent, other ions and surfactant existing in the reaction system will remarkably effect the morphologies of the products. A series of CuS crystals with distinctive structures have been obtained by systematical adjusting these factors and primary formation mechanism have also been studied.2. Metal sulfides doped with few other metal ions show better physical properties (such as electrical and photoelectrical conductivities) than the parent sulfides, and have potential applications in fields such as nanodevices. Using the well-defined concaved cuboctahedrons of CuS crystals as the templates, we have obtained CuS/Ag₂S composites and pure Ag₂S nanoparticles approximately retaining the morphology of the...