Series Of Zinc And Aluminum Functional Crystal Materials Were Synthesized With Carbonate Precursors By Solid Phase Reaction

Chapter One: The nano-crystals of zinc carbonate were synthesized via solid state reaction at room temperature,, when ZnSO4.7H2O reacts with NH4HCO3 using PEG-400 as template. The size of the nano-crystals are about 35nm.The experimental results showed that (1) The crystals with ideal crystallization as well as without impurity have been got, when keep NH4HCO3 excessive all the time. (2) It was no necessary to let the reaction mixtures deposited for crystallization, for the product of zinc carbonate had spontaneously crystallized to form ideal crystals within 20 minutes grinding time. On the contrary, the byproduct would be formed by long deposited time, and the byproduct is zinc carbonate hydroxide. (3) Template played key role for controlling composition of the product. The product were nano-crystals of zinc carbonate with template, and mixture was got without template, which contained zinc carbonate hydroxide as well as zinc carbonate, but zinc carbonate hydroxide was in majority. (4) Compared the product with that of micro-emulsion synthesis method reported in one literature, it was learned that the controlled role of the template was played via forming micro-emulsion with water releasing from crystal water of the reactants within the grinding process.Chapter Two: ZnO crystal whiskers were prepared via a simple thermolysis of carbonate, the growth process was carried out at 910℃ using sodium chloride as smelter flux. the products were identified by transmission electron microscopy(TEM) and X-ray diffraction analysis(XRD), the results showed that the ZnO whiskers have diameter ranging from 100 to 150nm and lengths ranging from 3.5 to 4.5um, We researched the growth mechanism of whiskers primarily, the results showed that (l)smelter flux play an important role in the growth process of whisker ,we cannot obtain whisker without smelter flux (2) Zinc oxide was solide state at 900℃,because the melting point of zinc oxide is 1975℃. So ,the growing mechanism of zinc oxide whiskers were not VS and VLS, the growth of whisker shows a new mechanism—self-assemble growth.Chapter Three: Using A12(SO4)3.18H2O and NH4HCO3, fibroid form AACH were prepared by solid phase reaction in room temperature. Based on the uniform design, the optimization parameters of the experiment were gained .The results showed that: solid phase reaction were superior to liquid phase reaction in reducing the outgrowth .Chapter four: Fibroid intermediate, which structure were aluminum oxygen framework connecting some boric acid radical, were prepared with fibroid ammonium aluminum carbonate (AACH) and boric acid via solid state reaction under a low temperature of 423K .Then the intermediate were roasted under a high temperature of 1373K for 4h in the presence of fluxing agent potassium sulfate and the mixture were obtained. The mixture was washed several times to remove the dissoluble fluxing agent and dried in an oven. The product was characterized with X-ray diffraction (XRD)as well as scanning electron microscopy (SEM).The characterized results indicated that theproducts exhibit one-dimensional structure with average diameters 0.3um and lengths about 45um. AACH keep the fibroid shape and the boric acid radical have connect with the aluminum-oxygen framework when it is decomposed into active alumina in low temperature. Based on these facts, the self-induction growth mechanism of the synthesis was suggested.