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实现高电磁屏蔽性能的同时降低反射是目前电磁屏蔽材料所追求的。采用一步水热法合成直径为30~40μm,厚度为70~200 nm的Fe3O4纳米片,利用红外光谱、X射线衍射仪、扫描电子显微镜表征发现结晶度良好。改变Fe3O4纳米片含量,喷涂制备的Fe3O4/MXene/WPU复合膜的反射值能低至4.3 dB,反射功率(R)从0.81降至0.63,透射功率(T)仅为10-3数量级。同样,采用水热法制备了直径为180~200 nm、分散性良好的Fe3O4纳米微球。同等Fe3O4含量下纵向对比发现,含Fe3O4纳米片的复合膜电磁屏蔽性能稍高于含Fe3O4纳米球的复合膜。 相似文献
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在水介质中以羧基取代度为1.2的羧甲基-β-环糊精对Fe3O4磁性纳米颗粒直接进行包覆修饰制备了羧甲基-β-环糊精修饰Fe3O4磁性纳米颗粒,对制备颗粒的形态、结构和成分进行了表征并对其相关性能进行了研究。结果表明,制备的羧甲基-β-环糊精修饰Fe3O4磁性纳米颗粒为近球形,粒径在15~20nm之间,修饰上的羧甲基-β-环糊精约占颗粒总重的8.2%,颗粒为超顺磁性,质量比饱和磁化强度为68.7emu/g,在水中分散良好,载药的羧甲基-β-环糊精修饰Fe3O4磁性纳米颗粒在4h内具有较强的药物突释效应,随后呈现长达26h以上的药物缓释状态。 相似文献
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为研究一种应用于磁稳定流化床反应器的新型高分子磁性微球的制备方法及性能,采用悬浮聚合法制备了Fe_3O_4纳米粒子包覆聚苯乙烯磁性微球,研究了搅拌速率、加入磁性Fe_3O_4纳米粒子的时间等因素对复合微球粒径及性能的影响,运用扫描电子显微镜(SEM)、X射线衍射(XRD)、振动样品磁强计(VSM)、热重(TGA)等测试手段,表征了磁性聚苯乙烯微球的形貌特征、结构、粒径、磁学性能及Fe_3O_4的包覆量.实验结果表明:在搅拌转速为600 r/min,80℃保温10 min加入修饰Fe_3O_4纳米粒子,制备所得的磁性聚苯乙烯微球为粒径分布均匀的球状微粒;Fe_3O_4的包覆量达到5%,最高饱和磁化强度为3.73 emu/g,具有较好的超顺磁性,可应用于磁稳定流化床反应器. 相似文献
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以化学沉淀法制备Fe3O4 纳米粒子, 采用乙醇对Fe3O4 纳米粒子表面进行处理, 使其表面有机化, 然后通过乳液原位复合制备Fe3O4 / 聚吡咯复合材料。利用TEM, XPS, 四探针测试仪和震荡磁力计对其进行表征和检测。结果表明: 经醇处理的Fe3O4 纳米粒子的分散性得到明显改善, Fe3O4 纳米粒子被包覆在聚吡咯层内, 包覆层厚度为10 nm 左右, 复合材料具有优良的电性能和磁性能, 电导率e= 7. 69 s/ cm~13. 6 s/ cm, 饱和磁强度Ms= 12. 06 emu/ g~24. 38 emu/ g, 矫顽力Hc= 11 Oe~41 Oe。其环境稳定性明显优于纯聚吡咯。 相似文献
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用水解沉淀法合成了纳米Fe3O4粒子,并在其悬浮液中原位包覆聚苯胺,制备出纳米Fe3O4/聚苯胺复合粒子。研究了两种纳米粒子在交变磁场下的发热性能,对它们在定向集热治疗肿瘤中的应用前景进行了评价。纳米Fe3O4粒子的粒径为10~30nm,表面包覆聚苯胺后,复合粒子的粒径为30~50nm。纳米Fe3O4粒子的比饱和磁化强度为50.05Am2/kg,矫顽力为10.9kA/m;纳米Fe3O4/聚苯胺复合粒子的比饱和磁化强度为26.34Am2/kg,矫顽力为0。在10mg/mL的生理盐水悬浮液中,在外加交变磁场作用30min后,纳米Fe3O4粒子悬浮液的温度为63.6℃,纳米Fe3O4/聚苯胺悬浮液的温度为52.4℃,二者均达到了医学上定向集热治疗肿瘤用热籽的发热要求,是很有应用前景的医用纳米材料。 相似文献
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Lan Zhang 《Materials Letters》2009,63(2):272-274
This study investigates the dielectric, magnetic, and microwave absorbing properties of Sm2O3-filled multi-walled carbon nanotubes (MWCNTs) synthesized by wet chemical method. The complex permittivity and permeability were measured at a microwave frequency range of 2-18 GHz. Sm2O3 nanoparticles encapsulated in the cavities enhance the magnetic loss of MWCNTs. The calculated results indicate that the bandwith of absorbing peak of the modified MWCNTs is much broader than that of unfilled MWCNTs. The maximum reflectivity (R) is about − 12.22 dB at 13.40 GHz and corresponding bandwidth below − 5 dB is more than 5.11 GHz. With the increase of thickness, the peak of R shifts to lower frequency, and multiple absorbing peaks appear, which helps to broaden microwave absorbing bandwidth. 相似文献
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《Materials Science & Technology》2013,29(1):180-183
AbstractMagnetic carbon nanotube (CNT) composites have been successfully fabricated by employing a microwave assisted method after sensitisation and activation. The phase structures and morphologies of the composites were characterised in detail by transmission electron microscope and X-ray powder diffraction. The results show that sensitisation and activation are absolutely necessary for a dense layer of magnetic nanoparticles obtained on the surface of CNTs. Magnetic measurements using a vibrating sample magnetometer demonstrate that the prepared composites are ferromagnetic. 相似文献
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An efficient method for decoration of the multiwalled carbon nanotubes with nearly monodispersed magnetite nanoparticles 总被引:1,自引:0,他引:1
Haitao Wang Lili Cao Shancheng Yan Ningping Huang Zhongdang Xiao 《Materials Science and Engineering: B》2009,164(3):141
A one-pot method has been developed to prepare magnetite nanoparticles decorated carbon nanotubes (CNTs) by thermal decomposition of iron chloride on CNTs templates in diethylene glycol. The morphological and structural characterizations indicate that magnetite nanoparticles are coated on the surfaces of the CNTs to form CNT-based nanocomposites. The density of magnetite nanoparticles on CNTs could be easily tuned by adjusting the weight ratio of iron chloride to CNTs. Magnetic measurements showed that the nanocomposites are superparamagnetic at room temperature and the magnetic properties of the samples can also be tuned by adjusting preparing conditions. The nanocomposites can be readily dispersed in water to form a stable solution and can be manipulated using an external magnetic field. As-synthesized nanocomposites may have potential applications in target–drug delivery, detection and separations, and in clinical diagnosis. 相似文献
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Copper nanoparticles were synthesized using carbon nanotubes as a template. The process involved neither pre-purification nor an additional reducing agent. This method was simple and the Cu nanoparticles were uniformly loaded on the carbon nanotubes. TEM, SEM, XRD and EDX were used to examine the morphology of the Cu particles. The diameter of the carbon nanotubes is about 70-90 nm and the size of the nanoparticles is about 50-70 nm. 相似文献
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A one-step synthesis route to carbon nanocapsules and nanotubes containing Fe and Fe3C nanoparticles is reported. Low power laser assisted pyrolysis of ferrocene yielded carbon nanocapsules (30-100 nm in diameter) and multi-wall carbon nanotubes (30-80 nm in diameter). The developed route is fast and enables one to synthesize the products at a rate of 84 mg/min. The iron content in the product (10-42 wt.%) can be varied by modulating the buffer gas pressure during the synthesis process. 相似文献
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Carbon nanotubes encapsulated Fe nanowire composites were synthesized via pyrolyzing of ferrocene. The reflection loss (R.L.), matching frequency (fm) and matching thickness (dm) were calculated using the theory of the absorbing wall. The electromagnetic properties and microwave-absorbing characteristic effects by the encapsulation of metal Fe were investigated in a frequency range of 8-18 GHz. With matching thickness of 3.5 mm, the maximum reflection loss is about − 22.73 dB for the absorber. The bandwidth corresponding to the reflection loss below − 10 dB is more than 4.22 GHz. With increasing thickness, the peak value of the reflection loss shifts to a lower frequency. 相似文献
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Magnetic graphitic carbon nitride nanocomposites (MGCN) were prepared by thermal treatment of a mixture of cyanamide and silica-coated Fe2O3 species nanoparticles. The thermal polycondensation of cyanamide in the mixture led to the encapsulation of silica-coated magnetic Fe species by graphitic carbon nitride, thereby forming MGCN nanocomposites. The samples were characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy and vibration sample magnetometer. The average particle size of MGCN nanocomposites was ca. 300 nm. The nanocomposites exhibited paramagnetic properties with a total magnetization value of 23.15 emu g− 1. The experimental results showed that such a process can directly in situ reduce α-Fe2O3 to yield magnetic cores in the absence of hydrogen. The possible mechanisms of the formation of MGCN nanocomposites and in situ reduction of α-Fe2O3 by NH3 from thermal polycondensation of cyanamide were proposed. 相似文献
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High saturation magnetization (>90 emu/g) multi-walled carbon nanotubes (MWCNTs) and Fe4N nanoparticles composite were successfully synthesized by gas nitriding at 550 °C. Almost all Fe4N nanoparticles were evenly distributed inside the carbon nanotubes and formed a special composite microstructure. This composite microstructure shows excellent soft magnetic property, structural stability, and chemical stability at room temperature. The investigations of electromagnetic and microwave absorption performances indicate that microwave absorbing capacity of low frequency band of MWCNTs were greatly improved by addition of Fe4N nanoparticles. 相似文献
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Lihua Zhai 《Materials Letters》2010,64(4):531-533
Hybrid composites of ZnS nanocrystals anchored on carbon nanotubes are prepared. Photochemical polymerization of acrylic acid is carried out using the ZnS nanocrystals as initiators. As a result of the surface polymerization, the modified CNT/ZnS hybrid composites are highly dispersed and the obtained solution exhibits long-term stability. In comparison, the synthesized poly(acrylic acid) exhibits higher thermal-stability. Investigations with Raman scattering reveal that ZnS nanocrystals interact with the carbon nanotubes, and the interaction is strengthened after UV irradiation. This study provides a new method to modify core-shell hybrid composites, and the obtained dispersible nanocomposites are useful for fabricating photoelectrical devices. 相似文献