| As an important one of the environmental oxide materials, iron oxide (α-Fe2O3) has a wide application prospect in the field emission display (FED), due to its good mechanical properties and chemical stability, diversified structures, simply synthesis, and environment-friendly. Thermal oxidation is a common method to grow Fe2O3 nanostructures directly from the Fe substrate, which has many advantages of a simple process, low cost and easy device manufacture. However, thermal oxidation has some problems, such as poor uniformity on a large area and difficult growth at low temperature.In this thesis, the growth and performance of Fe2O3 nanostructures mainly were investigated. The Fe2O3 nanostructures were grown from the Fe substrate at high temperature and oxidation environment. Especially, the Fe substrate was pretreated by oxalic acid (C2H2O4) before thermal oxidation. At the same time, the influence of oxalic acid pretreatment and thermal oxidation would be characterized by the aid of SEM, XPS and XRD. And then the field emission performance of the samples would be investigated to find out the optimum growth parameters of the Fe2O3 cathode, which with the best filed emission performance. Finally, Fe2O3/CNTs nanocomposite cathode was prepared by combining the nanorods Fe2O3 and CNTs for improving the some problems of CNTs cathode, such as the uneven distribution and agglomeration of CNTs, less tips and poor contact stability and etc. And the field emission performance of the composites would be studied to find out the optimum preparation parameters of the nanocomposite cathode with the best filed emission performance.The FeC2O4 nanorods would be formed by pretreating Fe substrate by oxalic acid, on the surface of the Fe substrate. It could provide the growth crystal nucleus in the proceeding of thermal oxidation, which improved the influence of the growth of Fe2O3 nanostructures. The results of oxalic acid pretreatment showed that the FeC2O4 nanorods array had big length-diameter ratio, good uniformity and moderate density.at the condition of oxalic acid pretreatment time of 5 h, oxalic acid solution concentration of 0.75 mol/L, oxalate pretreatment temperature of 25℃.The results of the growth of Fe2O3 nanostructures that in the thermal oxidation process, multilayer iron oxide would be formed on the Fe substrate by Fe and O atoms relative diffusion and molecular self-organization, the top layer of which was nanostructure Fe2O3. And the Fe2O3 with different structures of nanorods, nanoflakes, nanowires and nanobelts could be grown at the different conditions of thermal oxidation. The field emission performance of the nanowires Fe2O3 cathode was excellent, having low turn on field of 2.4 V/μm, high field enhancement factor of 9462, high luminous brightness of 2580cd/m2 at the optimized growth condition of the oxidation temperature of 600 ℃, oxidation time of 4h.Finally, novel field emission cathode with Fe2O3/CNTs nanocomposite emitters was prepared simply by the iron dipped into the oxalic acid solution, CNTs drop-coated to the Fe substrate followed by in-situ thermal oxidation. The CNTs of the Fe2O3/CNT nanocomposite cathode were homogeneously dispersed and partly wrapped on the Fe2O3 nanorods. And the nanocomposite cathode had better filed emission property than the Fe2O3 nanorods cathode and the CNTs cathode. Especially, the Fe2O3/CNTs composite cathode exhibited greatly enhanced field emission properties with low turn-on field (about 0.9V/μm), low threshold field (about 1.71V/μm), high field enhancement factor of 11620 and high luminous brightness of 3640cd/m2 at the optimized preparation condition of the oxidation temperature of 200 ℃, the CNTs dispersion concentration of 0.7g/L, oxidation time of 1.5h. |
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