| Rare-earth mental hexaborides(RB6) is a good cathode emission material having a low work function, and its hardness, high melting point, electrical conductivity Higher unique excellent mechanical and chemical characteristics, based onthis performance, hese materials can be widely used in the preparation of the field emission device, typically used for commercial and defense industries.Theoretical and experimental results show that the rare earth boride nanomaterials have more rich and interesting shape and excellent physical and chemical properties, and these excellent features they have more and better application value. Therefore, the study of such borides nanomaterials has a very important significance.In the desertion, aligned LaB6and NdB6nanowires were prepared by chemical vapor deposition and characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS), X-ray energy spectrum (EDS) and Raman spectrum were used to test the characters of the nanostructures. The growth mechanism of those nanostructures was simply discussed.In this thesis, using LaCl3.7H2O-as lanthanum source, B2H6as boron source which are used in high temperature and low pressure the autocatalytic method directly prepared by the reaction of a large area LaB6nanowires its array. The use of technical means of X-ray powder diffraction (XRD), field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, electron field emission instrument to analyze the morphology of its field emission properties of the nanomaterials. Through a field emission scanning electron microscopy shows that a large area of the nanowire deposition on the substrate of the sample.They have a similar flattened smooth obelisk-like morphology, and a uniform length and diameter, the vertical growth of the majority of the substrate nanowires with an average of approximately15μm, a diameter of about80nm.the aspect ratio of an average is about 200. HRTEM, selected area electron diffraction, X-ray powder diffraction analysis results show that the growth direction of LaB6nano line is [100] direction. In short, the growth mechanism of these LaB6nano line is VS mechanism. The use of chemical meteorology took the opportunity to process a large number of LaB6nanowire synthesis autocatalytic method in different conditions, through X-ray powder diffraction (XRD), field emission scanning electron microscopy, transmission electron microscopy (TEM), high resolution transmission electron microscopy analysis characterization of LaB6nanowires structure morphology, using electron field emission analysis LaB6nanowires. The test results show that:these LaB6nanowires have a low open field and threshold electric field, the field enhancement factor is also great, the emission current is relatively stable.While taking advantage of the similar CVD method, we successfully synthesized a number of NdB6nanowires, through an X-ray powder diffraction(XRD), field emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution transmission electron microscopy analysis of the way the test results show these preparation NdB6nanomore single line, and the morphology is more structured, a diameter of about100nm, and a length of about several micrometers, and the structure is relatively smooth and uniform, which is obviously a single crystal structure. Finally the the temperature on NdB6nanowire structures formed, the temperature is too low and too high are very influential on NdB6nanowire growth. The results show the VS mechanism of NdB6nanowire growth mechanisms.Finally, the thesis also discusses the preparation, characterization and performance of zinc oxide nano material. The results show that zinc oxide nano material prepared was simple and direct look good, high quality, good performance, and has good application value. |
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