共查询到19条相似文献,搜索用时 109 毫秒
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直流碳弧法制备碳包覆铁纳米颗粒机理研究 总被引:1,自引:1,他引:0
采用直流碳弧等离子体法成功制备了碳包覆铁纳米颗粒,利用透射电子显微镜和高分辨透射电子显微镜、X射线衍射、X射线能谱仪对样品的形貌、物相结构、化学成分和粒度进行表征分析,并对碳包覆纳米金属颗粒的形成机理进行初步探讨。结果表明:直流碳弧等离子体技术制备的碳包覆纳米金属颗粒具有明显的铁核(bcc-Fe)/碳壳(石墨层片)包覆结构,颗粒大多呈球形和椭球形,粒径分布在20~60nm范围,平均粒径为44nm,铁粒子外碳层的厚度为5~8nm。碳包覆铁纳米铁颗粒是通过颗粒内部固态形式的碳自行扩散至颗粒表面和颗粒外部气态形式的碳沉积到颗粒表面形成的。 相似文献
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研究了氢氧摩尔比例与二茂铁质量对制备碳包覆铁纳米颗粒的影响。通过氢气与氧气爆轰产生的高温高速, 在自制爆轰管内分解二茂铁, 合成了碳包覆铁纳米颗粒。经XRD分析与TEM表征发现, 氢氧比例与二茂铁质量在制备碳包铁时相互影响, 氢氧比例主要影响碳包铁的形貌大小及分散性, 二茂铁质量对能否合成碳包铁纳米颗粒影响很大。当氢氧比例为2:1, 二茂铁质量在2.5~3.5 g时, 能够合成碳包覆铁纳米颗粒, 且呈球形或椭球形, 具有明显的核壳结构。从颗粒大小均匀性, 形貌结构及分散性考虑, 氢氧比例2:1, 二茂铁质量3.5 g的反应条件是制备碳包铁的较佳方案。 相似文献
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淀粉基碳包覆铁纳米胶囊的合成及其磁学性能 总被引:3,自引:1,他引:3
以淀粉为碳源,通过热解炭化铁/淀粉复合物,成功制备出碳包覆铁(Fe@C)纳米胶囊。在这一过程中淀粉有双重作用,既是碳源又是铁纳米颗粒的稳定剂。采用透射电镜、X射线衍射及振动样品磁强计研究了(Fe@C)纳米胶囊的结构和磁学性能。发现Fe@C纳米胶囊具有完美的铁核(bcc-Fe)/碳壳(石墨层片)包覆结构,其尺寸介于30nm~40nm之间;Fe@C纳米胶囊在室温下有低的剩磁比(Mr/Ms=0.11),表明它在室温下具有超顺磁性。 相似文献
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快速热解法制备炭包覆纳米金属磁性颗粒(英文) 总被引:1,自引:0,他引:1
以简单金属前躯体为原料通过快速热解法制备炭包覆纳米金属磁性颗粒,通过透射电镜、X-射线衍射、热重-示差扫描同步热分析及振动样品磁强计等对产物形貌、结构、成分与磁性能进行表征。结果表明:采用该方法制备的炭包覆纳米金属磁性颗粒形状为近球形颗粒,粒径均一,其中炭包覆镍纳米磁性颗粒的粒径集中在10nm~30nm范围,炭包覆铁纳米磁性颗粒粒径则在50nm~60nm范围;所制炭包覆纳米金属磁性颗粒在室温下具有顺磁性,其磁性能随金属颗粒含量的变化而改变。该方法有望发展成一种工艺简单,可进行连续工业化生产炭包覆纳米金属磁性颗粒的方法。 相似文献
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纳米碳包铁磁性颗粒的制备及表征 总被引:2,自引:0,他引:2
采用激光感应复合加热蒸发合成法,以CH4为碳源,制备了大量具有壳核结构的纳米碳包铁颗粒,通过透射电子显微镜(TEM)、X射线衍射分析仪(XRD)、能量弥散X射线分析(EDX)等对颗粒进行了表征,并利用动态磁滞回线测定仪测定了纳米颗粒的磁化强度等磁性能.结果表明,利用该方法制备的碳包铁纳米颗粒的平均粒径为25nm,表面碳层厚度为5nm左右,具有铁磁性能.纳米碳包铁颗粒将作为磁性载体在医学细胞分离、细胞染色、靶向用药、定向治疗、肿瘤热疗等方面具有广阔的应用前景. 相似文献
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Ja Young Park Mi Ae Kim Seung Jae Lee Jongjin Jung Hye Mi Jang Pravin P. Upare Young Kyu Hwang Jong-San Chang Joung Kyu Park 《Journal of Materials Science》2015,50(1):334-343
This study describes the synthesis of carbon-encapsulated iron nanoparticles using an ultrasonic method and also investigates their catalytic activity. These nanoparticles have been prepared using ultrasonic irradiation followed by annealing at various temperatures. As the annealing temperature of as-prepared α-Fe2O3 nanoparticles increased, the sample transformed into γ-Fe2O3, Fe3O4, and Fe nanoparticles via the reduction process without requiring any additional reducing agents such as H2 gas, thus, creating a carbon shell surrounding the nanoparticles. By controlling the experimental conditions, Fe nanoparticles of various sizes can be formed with diameters in the range 100–800 nm; these nanoparticles are tightly encapsulated by 20-nm-thick carbon shells. Because of their high saturation magnetization 212 emu g?1, the carbon-encapsulated Fe nanoparticles can be used for magnetic resonance imaging with a dramatically enhanced efficiency compared to commercially available T 2 contrast agents. Moreover, the carbon-encapsulated Fe nanoparticles showed its superior catalytic activity and reusability for the hydrogenation of biomass-derived levulinic acid to GVL (99.6 %) in liquid phase. 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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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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以二茂铁为铁源,石油渣油为碳源,通过加压热解和空气氧化制备了碳包覆空心Fe3O4纳米粒子。采用X射线衍射(XRD)、透射电镜(TEM)以及高倍透射电镜(HRTEM)等测试方法对样品的形貌和结构进行表征。采用恒流充放电和交流阻抗方法测试碳包覆空心Fe3O4纳米粒子作为锂离子电池负极材料的电化学性能。在电流密度为0.2mA/cm2时,首次放电比容量高达1294.7mAh/g,30次循环之后其放电比容量为392.1mAh/g;电流密度为1mA/cm2时,首次放电比容量为216.3mAh/g,30次循环之后其放电比容量为113mAh/g。 相似文献
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磁性羧甲基化壳聚糖纳米粒子的制备与表征 总被引:1,自引:1,他引:0
以化学共沉淀法制备了Fe3O4纳米粒子,壳聚糖经羧甲基化改性后接枝在Fe3O4颗粒表面,得到了磁性羧甲基化壳聚糖(Fe3O4/CMC)纳米粒子.利用透射电镜(TEM)、X射线衍射(XRD)、傅立叶红外光谱(FT-IR)及磁性测试对产物进行了表征.TEM表明Fe3O4纳米粒子被CMC包覆,粒径约10 nm;XRD分析表明复合纳米粒子中磁性物质为Fe3O4;FT-IR表明壳聚糖发生羧甲基反应以及在Fe3O4表面的接枝反应.Fe3O4/CMC纳米粒子具有超顺磁性,比饱和磁化强度25.73 emu/g,有良好的磁稳定性. 相似文献
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Meneses-Rodríguez D Muñoz-Sandoval E Ramírez-Manzanares G Ramírez-González D Díaz-Castañon S Faloh-Gandarilla JC Morelos-Gómez A López-Urías F Terrones M 《Journal of nanoscience and nanotechnology》2010,10(9):5576-5582
We report the production, characterization, thermal transformations (400-1000 degrees C), and magnetic properties of nanoparticles encapsulated in nitrogen-doped multiwall carbon nanotubes (CNx-MWNT), which were embedded in silicon oxide (SiOx) matrices via sol-gel techniques. The vapor chemical deposition (CVD) method with ferrocene-benzelamine mixtures was used to synthesize Fe and Fe3C nanoparticles inside CNx-MWNTs. Composites consisting of CNx-MWNTs (filler) and SiOx (matrix) were fabricated and thermally treated to different temperatures and exposure times (t). All samples were characterized using scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), thermogravimetic analysis (TGA), and magnetometry (vibrating sample). We found that upon thermal treatment, the ferromagnetic nanoparticles modify their morphology, composition and aspect ratio, thus resulting in drastic changes in the magnetic and structural properties. In particular, as produced encapsulated nanoparticles mainly consisting of Fe and Fe3C phases were thermally modified into magnetite (Fe3O4). We have also observed that the hysteresis loops are very sensitive to the thermal treatment of the sample. Thus we can control the magnetic properties of the samples using thermal treatments. 相似文献
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Co-Pt nanoparticles encapsulated in carbon cages have been prepared by sonoelectrodeposition followed by annealing in a CO atmosphere. Sonoelectrodeposition is a useful technique to make metallic nanoparticles, using ultrasound during electrodeposition to remove nanoparticles as they grow on the cathode surface. We used an electrolyte containing chloroplatinic acid and cobalt chloride and found that the atomic ratio of Co:Pt in the as-formed materials varied from 0.2 to 0.8 as the deposition current density was changed from 15 to 35 mA cm(-2). However, the as-deposited materials were inhomogeneous, comprising a mixture of Pt-rich and Co-rich nanoparticles. X-ray diffraction indicated that subsequent heat treatment (700?°C for 1 h) under CO gas created an ordered CoPt alloy phase that exhibited hard magnetic properties. Transmission electron microscopy showed many of the resulting nanoparticles to be encapsulated in carbon cages, which we ascribe to Co-catalyzed decomposition of CO during annealing. The thickness of the carbon cages was about ten layers, which may have helped reduce sintering during annealing. The size of the resultant nanoparticles was about 100 nm diameter, larger than the typical 5-10 nm diameter of as-deposited nanoparticles. 相似文献
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Metal–organic framework (MOF) composites have recently been considered as promising precursors to derive advanced metal/carbon‐based materials for various energy‐related applications. Here, a dual‐MOF‐assisted pyrolysis approach is developed to synthesize Co–Fe alloy@N‐doped carbon hollow spheres. Novel core–shell architectures consisting of polystyrene cores and Co‐based MOF composite shells encapsulated with discrete Fe‐based MOF nanocrystallites are first synthesized, followed by a thermal treatment to prepare hollow composite materials composed of Co–Fe alloy nanoparticles homogeneously distributed in porous N‐doped carbon nanoshells. Benefitting from the unique structure and composition, the as‐derived Co–Fe alloy@N‐doped carbon hollow spheres exhibit enhanced electrocatalytic performance for oxygen reduction reaction. The present approach expands the toolbox for design and preparation of advanced MOF‐derived functional materials for diverse applications. 相似文献