M. Montazeri-Pour
材料科学技术（英文）
Nanocrystalline particles of barium ferrite magnetic material have been prepared by co-precipitation route using aqueous and non-aqueous solutions of iron and barium chlorides with a Fe/Ba molar ratio of 11 and subsequent drying-annealing treatment. Water and ethanol/water mixture with volume ratio of 3:1 were used as solvents in the process. Coprecipitated powders were annealed at various temperatures for 1 h. FTIR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), DTA/TGA (differential thermal analy-sis/thermogravimetric analysis) and SEM (scanning electron microscopy) techniques were used to evaluate powder particle characteristics. DTA/TGA results confirmed by those obtained from XRD indicated that the formation of barium ferrite occurs in sample synthesized in ethanol/water solution at a relatively low temperature of 631°C. Nano-size particles of barium ferrite with mean particle size of almost 75 and 100 nm were observed in the SEM micrographs of the samples synthesized in ethanol/water solution after annealing at 700 and 800°C for 1 h, respectively.
关键词:
Magnetic materials
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null
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null
Yongrui LI
,
Nanlin SHI
材料科学技术（英文）
Ultrafine Fe3O4 powder was successfully synthesized via a novel ageing process from a precursor FeO(OH), which was the hydrolysate of FeCl3 in the urea solution. The structure of as-synthesized powder was characterized by X-ray diffraction (XRD), and the morphology of these nanoparticles was investigated using a transmission electron microscope (TEM). Pure phase Fe3O4 was obtained and the mean diameter of these nanoparticles was about 21nm. Furthermore, the study indicated that the precursor FeO(OH) played an important role in the formation of Fe3O4 nanoparticles. The mechanism was also discussed.
关键词:
Powder technology
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null
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null
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null
Minglong Zhong
材料科学技术（英文）
Quasi-one dimensional iron oxide nanowires with flat needle shape were synthesized on the iron powders by a rather simple catalyst-free thermal oxidation process in ambient atmosphere. The characterization by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman and high-resolution transmission electron microscopy (HRTEM) revealed that these nanostructures are single crystalline α-Fe2O3. The various dimensions with 40-170 nm in width and 1-8 μm in length were obtained by tuning the growth temperature from 280 to 480°C. A surface diffusion mechanism was proposed to account for the growth of quasi-one dimensional nanostructure. The typical α-Fe2O3 nanowires
synthesized at 430°C had a reduced Morin temperature TM of 131 K in comparison with their bulk counterpart. The coercivitis Hc of these nanowires are 321 and 65 Oe at 5 and 300 K, respectively. The temperature of synthesis also has important effects on the magnetic properties of these nanowires.
关键词:
Thermal growth
范秀娟
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李欣
新型炭材料
doi:10.1016/S1872-5805(12)60007-9
通过FeCl2·4H2O和FeCl3·6H2O混合共沉淀,合成平均粒径为6nm和10 nm的Fe3O4纳米粒子.然后将两种Fe3O4纳米粒子分别与经HNO3氧化处理的多壁碳纳米管(MWCNTs)置于乙醇水溶液(水和乙醇的体积比为1∶1)中,在超声波作用下制备Fe3O4/MWCNT复合材料.用高分辨透射电子显微镜、X-射线光电子能谱、振动样品磁强计、X射线衍射仪、热重分析仪对所制备的Fe3O4/MWCNT复合材料进行表征.结果表明:由6nm和10 nm Fe3O纳米粒子所制备的Fe3O4/MWCNT复合材料中,Fe3O4的质量分数分别为26.65％和29.3％,相应的磁饱和强度分别为16.5 emug-1和7.5emug-1.
关键词:
碳纳米管
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修饰
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Fe3O4
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磁性纳米材料
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纳米复合材料
