Study On Hydrothermal/solvothermal Synthesis Of Hydroxyapatite And Zinc Oxide

The hydrothermal/solvothermal technology is becoming one of the most important tools for the processing of advanced materials as well as the preparation of nanomaterials. It is environmentally benign and inexpensive. The size and the morphologies of the nano particles obtained via the hydrothermal/solvothermal method were homogeneous and controllable. And the products obtained via the techniques had higher purity and better crystallinity compared to other methods. It is a new route to synthesize nano materials with novelty properties.In this study, hydrothermal and solvothermal approaches were used to synthesis hydroxyapatite and zinc oxide with nano-scale sizes and complex nanostructures. These experiments included: 1. the preparation of hydroxyapatite and CDHA by using Ca(NO₃)₂ and P₂O₅ /(NH₄) H₂PO₄ as precursors, and ethylenediamine as the template. 2. the synthesis of large scale hydroxyapatite whiskers by using Ca(NO₃)₂ and (NH₄) H₂PO₄ as the precursors and the sulfanilamide as the precursor and the template via a two-step approach. 3. the fabrication of ZnO spheres and hollow spheres by using zinc acetate, zinc nitrate and ethylene glycol as the precursors and ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate (C₈H₁₅N₂BF₄) [bmim][BF4] as the precursor and the template. 4. the two-step synthesis of ZnO with a pinecone-like architecture using zinc acetate and sulfanilamide as the precursors. 5. the synthesis of nano-ZnO suspension by using zinc acetate, ethylene alcohol and ethyl alcohol as the precursors or as the solvents during solvothermal processing. The resultant samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier infrared spectrophotometer (FTIR), ultraviolet spectrophotometer (UV) and Brunauer- Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) analysis.The results from the experiments of the synthesis of hydroxyapatite showed that when ethylene alcohol and ethyl alcohol were used as the precursors, homogeneous HA nano near-spheres were obtained. It was found that the crystal size decreased and crystallinity was enhanced with increasing the reaction temperature. The same trend was also observed during the synthesis of CDHA. The obtained HA powder presented fantastic flowability and dispersity. Large scale hydroxyapatite whiskers with needle-clusters on the surfaces of hydroxyapatite whiskers were produced via a two-step approach when Ca(NO₃)₂ and (NH₄) H₂PO₄ were used as the precursors and the sulfanilamide as the precursor and the template.The results from the experiments of the synthesis of ZnO showed that hollow micro-spheres have been synthesized by using a simple one-pot solvothermal route and that their microstructures were successfully tuned by IL, which exhibited quite different nanostructures and porous structures compared to hollow micro-spheres without being tuned by IL. These extraordinary microstructures might bring about quite different changes in the properties of materials. These hollow micro-spheres tuned by IL were monodispersed and had a high yield. Pinecone-like zinc oxide has also been synthesized via a simple hydrothermal approach followed by thermal treatment. This strategy that incorporates two or more steps has been proven to be applicable for the synthesis of some metal oxides with special morphology, which can provide a potential approach for the synthesis of these metal oxides. In the present study, it can be found that "the space effect" and secondary crystals can play crucial roles in controlling architectures of ZnO. Finally, the nano-ZnO suspension was achieved vai a facile solvothermal approach. The obtained nano ZnO presented excellent dispersity in not only de-ionized water but also ethanol and acetone for long time.