Self-assembly And Mechanism Of One-dimensional Nanometerials By Low-heating Temperature Solid-state Reaction

One-dimensional nanostructure materials such as wires, rods, belts, and tubes have become the focus of intensive research owing to their interesting properties and potential applications. Many attempts have been made to synthesize one-dimensional nanostructure materials using a variety of nanofabrication techniques and crystal growth methods, such as vapor-liquid-solid, solvothermal synthesis, assistant-template, and other methods. However, extremely special conditions, long synthesis time, complex apparatus, or higher reactive temperature often be required for these methods. So it is very important to find a simple and facilitate way to synthesize one-dimensional nanomaterials.It has been confirmed that solid-state chemical reaction method at low-heating temperature is one of simple and effective methods to fabricate cluster compounds, NLO materials, oxides and sulfides nanoperticles. In this thesis, the low-heating temperature solid state reaction method has been systematically investigated for the chemical self-assembly route to one-dimensional nanomaterials. The effects of themolecular structure of reactants and reaction products on the morphologies of reaction products were also studied. The synthesis methods have shown many advantages such as no need for solvent, high productivity and selectivity, low energy consumption and simple reaction technology.1% ZnO nanospheres was prepared by one-step solid-state chemical reaction of zinc salt and sodium hydroxide, ZnO and PbO nanorods were synthesized by solid-state chemical reaction of zinc (lead) salt and NaOH in the presence of PEG 400. The compositions of samples were determined by XRD. The sphere-like or rod-like morphology of samples were observed by TEM and SEM. The reactive processes and mechanisms of one-step solid-state reaction were discussed. It can be summarized that oxide can be directly obtained by solid-state reaction of metallic salt and NaOH or KOH if corresponding metal hydroxides have low decomposition temperature or are of unsteadiness.2n Cd(OH)2 and Co(OH)2 nanorods were synthesized by solid-state chemical reaction of different metallic salt and NaOH in the presence of PEG 400. The compositions of samples were characterization by XRD and TG-DTA. The rod-like morphologies of samples were observed by TEM and SEM. The morphologies of samples were also investigated when different salts were selected as reactants. Results show that the morphologies of samples are different when reactants have different structures. The mechanism of one-dimensional Cd(OH)2 and Co(OH)2 nanorods by low-heating temperature solid state chemical self-assembly reaction method were also studied.3s COC2O42H2O, CUC2O4, and NiC2O4-2H2O nanorods and hollow ZnC2O4-2H2O, MgC2O4-2H2O, MnC2O4-2H2O and SrC2O4-2H2O nanostructures with different morphologies were synthesized bysolid-state chemical reaction of metallic salts and oxalic Acid in the presence of PEG. The compositions of samples were characterization by elemental analyses and XRD. The hollow structures of samples were observed by TEM and HRTEM. Their integral morphologies were observed by SEM. The structural water of samples was determined by TG and IR. The formational mechanism of nanorods and the hollow structures of samples were also discussed. It was found that the surfactant plays an important soft-template role in the growth process of nanorods.4> Trans-[Cu(glyo)2(H2O)] nanoparticles with average diameters about 20-30 nm were prepared by one-step room temperature solid-state reaction. 7ra/i.s-[Cu(glyo)2] nanorods with diameters ranging from 100 to 150 nm and length up to several fim were also prepared by one-step room temperature solid-state reaction in the presence of a suitable nonionic surfactant PEG400. The chemical composition and structural features of the products were investigated by elemental analyses, XRD, TG, SEM and TEM, respectively. The results show that surfactant PEG400, which changes not only the composition of the products, but also the morphology of the products from nanoparticles to nanorods, plays an important role in the formation of the products. The mechanisms of formation were also discussed. Moreover, it is expected that the present synthesis method may be extended to prepare other functional nano-complexes with controlled morphologies if a suitable surfactant is used.5n Organic-inorganic hybrid lead iodide nanorods are synthesized by one-step room temperature solid-state reaction of lead nitrate with potassium iodide in the presence of a nonionic surfactant, polyethylene glycol. The chemical composition and structural features of the products were investigated by elementary analysis, XRD, IR, TG, SEM and TEM,respectively. The surfactant polyethylene glycol, which not only chemically banding with lead iodide but also greatly impacts the morphology of the products, plays an important role in the formation of the products. The lead iodide nanorods modified by PEG600 distribute evenly with glide surface whose diameters are ranging from 100 to 200 nm and lengths are up to 2 jum.6^ Based on the results of the experiment, the influence of different surfactant, the addition order of surfactant, the structure of the reaction materials and products on the formation morphology were discussed respectively. And the formation mechanism of one-dimensional nanostructure materials by room-temperature, solid-state reaction was primarily studied. Thus, one-step, room-temperature, solid-state reaction method introduced in the present work may provided a new path to fabricate one-dimensional nanostructured-materials.