Study On The Preparation And Properties Of Metal Chalcogenide Nanomaterials

The metal chalcogenide semiconductors have attracted much attention due to their unique physical,chemical properties and the widely applications in many fields,such as electronics,magnetics,optics,etc.If applied as basic building blocks,they also play an important role on the properties of assembling nano-/micro-apparatus.Therefore,it was important to investigate the structures,morphologies and synthetical technologies of nano semiconductors.As typical materials of binary semiconductors,copper chalcogenides(e.g.Cu2O,copper sulfide and copper selenide),ZnO and lead chalcogenides(e.g.PbS,PbSe and PbTe)have attracted considerable attention owing to their wide applications in catalysts,photoelectric transition,luminescence,piezoelectricity,gas sensor,thermoelectricity materials,etc.It was well known that the properties of materials were mainly determined by composition,structure of crystal itself according to previous studies,however,the size and shape of materials also played important roles to determine their applications and properties.Thus,controlled synthesis on the size and shape of nano-semiconductors will largely increased their scientific significances and widen the corresponding technical applications.In this study,we prepared a number of important metal chalcogenide nano/micro crystals by thermal decomposition,We can regulate the shape and size of the product by adjusting the ratio of the starting material,the type of solvent,and the reaction temperature,and the formation mechanism of the products were discussed.The main contents of this dissertation could be summarized in four sections:In chapter 1:We introduced the conception,preparation method of nanomaterials,the theory of luminescence and the luminescent materials,and presented the current research status of the metal chalcogenide nanomaterials preparation.In chapter 2:The second chapter is divided into two sections,in the first section,CuCl and sulfur were employed as reactants to synthesize CuS via the thermal decomposition.The product was first characterized by XRD.The result shows that the as-prepared product has a hexagonal phase and good crystallinity.The morphology and particle size of the product were characterized by SEM and TEM.Results show that CuS nanosheets are formed at the initiation stage and then the nanosheets grow into tetradecahedron nanocrystal.Moreover,the effects of reaction time on the morphology of the product were also investigated,and the as-obtained intermedia products were characterized by SEM.Then a mechanism was proposed to the formation of the tetradecahedron nanocrystal.in the second section,CuCl and sodium diethyldithiocarbamatre(NaDDTC)as reactants and oleylamine(OM)as solvent.Cu1.95S nanowires were successful synthesized via the thermal decomposition.XRD shows that the product has a cubic phase.The morphology of Cu1.95S was characterized by SEM and TEM,the result shows that the product has spindle-like structure.In chapter 3:we firstly synthesized(ZnxMn1-xS)2·L(L=octylamine)complex by using water/solvent hot.And with it as a single-precursor,in the high boiling point solvent(oleic acid,and oleic oil amine),we got high quality ternary Mn2+-doped ZnS nanorods by using the thermal decomposition.XRD results show that the product with high purity and crystallinity.Using SEM and TEM for observing morphology and size of products,proves that the resulting product structure,and its distribution is very uniform.In chapter 4:In the first section,zinc acetate,manganese acetate and selenium as reactants and octylamine as solvent.(ZnSe)2·L(L=octylamine)nanorods were successful synthesized via a solvothermal method.And then,the(ZnSe)2·L(L=octylamine)as a single source precursors to synthesis ZnSe nanotubes or nanosheets.XRD test results show that the structure of products have a hexagonal.The morphology and particle size of the products were characterized by SEM and TEM.In the second section,we used the same method for the synthesis of ternary precursors(ZnxMn1-xSe)2·L(L=octylamine)precursor.Then we got high quality ternary Mn2+-doped ZnSe ultrathin nanoribbons by using the thermal decomposition.Using TEM,XRD and other test methods on the morphology and components characterized by analysis,and finally,we used UV-vis and FL testing the optical properties of the sample.