| With its unique structure, excellent physical-chemical properties and wide application prospects, a material for micro/nano materials, has become one of the focus for the research and development in micro/nano science fields. Up to now, many different kinds of methods have been developed for preparation of micro/nano materials, which have special physical-chemical properties. Different morphologies of micro/nano materials, their performances will vary.Research work for this paper mainly focuses on the following two aspects: on the one hand, this paper focuses on the hydrothermal method for functional hollow spheres materials-cobalt oxide(Co3O4) hollow spheres, in order to offer a simple and green synthetic methods to meet the different performance requirements, and make a exploratory research for a static magnetic and photoluminescence aspects of the as-prepared Co3O4 hollow spheres; on the other hand, the paper synthesized fibrous β-type silicon carbide(β-SiC) nanowhiskers utilizing molten-salt method, aiming at provide a low-cost synthetic methods to meet the needs of industry and national defense, and also carried out a detailed study for its absorbing properties. Specific contents are as follows:(1) By hydrothermal method, using glucose(C6H12O6) as the carbon source, cobalt nitrate hexahydrate(Co(NO3)2·6H2O) as cobalt source, one-step synthesis for cobalt oxide solid spheres(C@Co3O4) are successfully made, after roasting removal of the carbon nucleus, at 550 oC in air, and get consistent morphology of cobalt oxide hollow spheres(Co3O4); Through molten salt method, using elemental silicon(Si) and multi-walled carbon nanotubes(MWCNT) as the source of silicon and carbon respectively, in a sodium chloride-sodium fluoride(NaCl-NaF) binary salt medium, holding six hours at a lower temperature(1250 oC), and finally acquire the bamboo-like β-SiC nanowhiskers.(2) In order to analyze the morphology, composition and structure of the as-synthetic materials, many characterization methods are used, such as XRD, SEM, TEM, XPS and Raman testing. The results discovered: synthetic Co3O4 has an obvious hollow structures, which containing countless tiny particles in the surface, and its productivity is up to 75%; For β-SiC nanowhiskers, all of them have bamboo-like morphologies with a contact forms between the layers, and its average diameter is 150~250 nm.(3) Superconducting quantum interference device and F-320 fluorescence spectrometer were used for the testing of static magnetic and photoluminescence behavior in terms of the Co3O4 sample, at room temperature. Results show that, Co3O4 hollow micro/nano spheres have a weak ferromagnetism and a good photoluminescence behavior.(4) By using coaxial transmission line method and the equipment: Hewlett-Packard(HP) 8720 B Vector Network Analyzer made in US, the electromagnetic parameters for the β-SiC paraffin composite samples in the range of 2-14 GHz are tested, and then further study its absorbing properties via the electromagnetic parameters. According to the obtained electromagnetic parameters, the dielectric loss factor and microwave reflection loss value(RL) for the sample in the range of 2-14 GHz are accurately calculated. The results show that: the electromagnetic parameters of β-SiC nanowhisker varies more obviously, the average value of the dielectric loss factor is 0.6, which is higher than that has reported in other articles; Especially, when the matching thickness is only 1.9 mm, the reflection loss value reaches its minimum-48.13 dB, indicating an excellent absorbing properties for β-SiC nanowhisker materials. |
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