Synthesis, Characterization And Optical Properties Of Ⅱ-Ⅵ Chalcogenides Nanostructures By Hydrothermal Process

Nanostructures - structures that are defined as having at least one dimension between 1 and 100 ran have received steadily growing interests as a result of superior to their bulk counterparts. The ability to generate such minuscule structures is essential to much of modern science & technology. Recently, one-dimensional (1D) nanostructures (such as rods, wires, belts and tubes) and hollow nanostructures have become the focus of intensive research owing to their unique applications in mesoscopic research and fabrication of nanoscale devices.As is known, the study of semiconductor nanomaterials is one of the most active areas due to their distinguished optical and electronic properties that are far from those of bulk substances. Like other semiconductors, metal chalcogenides are rather interesting materials. 1D metal sulfide nanomaterials can exhibit special optical and electrical properties compared with semiconductor quantum dots. Therefore, the synthesis of 1D metal sulfide nanomaterials is of great importance. At present, the control of the size and morphology of chalcogenide nanocrystals has been a primary focus.Hydrothermal or solvothermal approach is a commonly used methodology for generating nanostructures. The major advantage of this approach is that mostmaterials can be made soluble in a proper solvent by heating and pressuring the system close to its critical point. Since Health and co-workers creatively synthesized semiconductor nanowires, this method has been extensively exploited to process a rich variety of materials into wire, tubes and rods. As a result, we choose it as a chief synthetic method in our study.In this thesis, we synthesized and studied certain Ⅱ-Ⅳ chalcogenides nanostructures using hydrothermal synthesis method. The as-obtained product was investigated by X-ray diffractometer (XRD), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FE-SEM) and ultraviolet (UV)-visible spectrum. The main contents of our work are as follows:1 Hydrothermal Synthesis of Spindle-like ZnS Hollow NanostructuresSpindle-like hollow nanostructures of Zinc sulfide (ZnS) have been successfully synthesized by hydrothermal process using a simple surfactant emulsion template. It is found that most of the products including twin ellipsoids with connected hollow cores are reminiscent of spindle-like structures. The lengths, widths and the thickness of the shell are in the range of 1-2 μm, 300-450 nm and 20-40nm, respectively. Selected area electron diffraction (SAED) and X-ray powder diffraction (XRD) patterns show that the shell is composed of sphalerite ZnS polycrystals.2 Hydrothermal Synthesis of ZnO Nanorods via PVA AssistantZnO nanomaterials with one-dimensional (1D) structures have particular electronic and optoelectronic properties that may raise potential applications in many fields. In this work, 1D ZnO nanorods have been successfully prepared by hydrothermal process with PVA as assistant under mild conditions. The morphology and structure of the products have been characterized by means of TEM, ED and XRD. It is indicated that the as-obtained nanorods is wurtzite ZnO with diameters ranging from 50 to 80 nm and lengths ranging from 1 to 2 microns. The results also show that PVA molecules play a crucial role in the formation of 1D ZnO...