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1.
Facile Fabrication of Fe_3O_4@TiO_2@C Yolk–Shell Spheres as Anode Material for Lithium Ion Batteries
Transition metal oxides have been actively exploited for application in lithium ion batteries due to their facile synthesis,high specific capacity,and environmental-friendly.In this paper,Fe_3O_4@TiO_2@C yolk-shell(Y-S) spheres,used as anode material for lithium ion batteries,were successfully fabricated by Stober method.XRD patterns reveal that Fe_3O_4@TiO_2@C Y-S spheres possess a good crystallinity.But the diffraction peaks' intensity of Fe_3O_4 crystals in the composites is much weaker than that of bare Fe_3O_4 spheres,indicating that the outer anatase TiO_2@C layer can cover up the diffraction peaks of inner Fe_3O_4 spheres.The yolk-shell structure of Fe_3O_4@TiO_2@C spheres is further characterized by TEM,HAADFSTEM,and EDS mapping.The yolk-shell structure is good for improving the cycling stability of the inner Fe_3O_4 spheres during lithium ions insertion-extraction processes.When tested at 200 mA/g,the Fe_3O_4@TiO_2@C Y-S spheres can provide a stable discharge capacity of 450 mAh/g over 100 cycles,which is much better than that of bare Fe_3O_4 spheres and TiO_2@C spheres.Furthermore,cyclic voltammetry curves show that the composites have a good cycling stability compared to bare Fe_3O_4 spheres. 相似文献
2.
桂维玲 《实验室研究与探索》2008,27(11)
用超顺磁性氧化铁制备磁共振造影剂的报道较多,其中的磁粒均为Fe3O4。本文提出了用Fe2O3的可行性,并根据超顺磁性理论推导出两种微粒显示超顺磁现象的临界尺寸理论值分别为24.8nm、31.6 nm,在1.5T磁共振磁场中的临界值为7.1 nm、11.1 nm;根据磁学理论,分析了磁共振造影剂稳定的机理;推导出在磁共振磁场中,两者在造影剂中稳定悬浮的极限尺寸为13.3 nm、14 nm。得出在造影剂中,两者既能稳定悬浮又具有超顺磁性的临界尺寸为7.1 nm、11.1 nm的结论。同时分析了两者用做磁共振胃肠造影剂的优劣点。 相似文献
3.
磁流体的制备与分散技术 总被引：3，自引：0，他引：3
本文利用酸蚀法和复合法分别制备了复合铁酸锌镍、铁酸锌、铁酸镍、铁酸钡磁流体,通过沉降实验,重点考察了这些磁性纳米粉在水相中的分散方法和技术,对磁性粉体的液相分散技术进行了探讨。 相似文献
4.
1IntroductionApplication of Mn-Zn ferrites in power electronics isconstantly expanding. Demands on small and efficientswitching power supplies are rising to meet therequirement of compact and power saving electronicequipment . In a switching power supply, the trans-former takes up a large portion of cubage and powerloss .It is thereforei mportant to reduce the power lossof Mn-Zn ferrites used as the transformer core .Core loss is known to be dividable into three com-ponents :hysteresis loss … 相似文献
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6.
微乳液法制备纳米Fe3O4磁性颗粒的研究 总被引：7，自引：0，他引：7
在没有惰性气体保护下，以工业煤油作油相、AEO3＋TX10作表面活性剂、正丁醇作助表面活性剂，分别配成含FeSO4、Fe（NO3）3和NaOH的两种微乳液，采用双乳液混合法制备纳米磁性Fe2O4微粉，并研究了不同的工艺条件对产物物相组成和粒径的影响，得出了最佳实验工艺条件。最后，对所制备产物的性能进行了分析和测试，结果表明：产物的饱和磁化强度较大，矫顽力较小（几乎为零），呈现超顺磁性．是较好的软磁材料。 相似文献
7.
磁流体对工业废水中Cr（Ⅵ）的吸附 总被引：1，自引：0，他引：1
采用共沉淀法制备了粒径为10nm的Fe3O4磁性微粒,分散于水中生成饱和磁化强度35mT的水基磁流体,用此磁流体对模拟与实际废水中Cr（Ⅵ）进行了吸附研究。结果表明,吸附的最佳实验条件为pH=3,温度为45℃,吸附时间为0．5h。用Langmuir等温模型和假二级动力学模型探讨了磁流体对Cr（Ⅵ）的吸附机理,该过程为单离子层吸附。在最佳实验条件下,磁流体对实际制革废水中Cr（Ⅵ）的饱和吸附量达66．5mg／g,废水中残N／Cr（Ⅵ）浓度为0．2mg／L,低于工业废水排放的国家标准（0．5mg／L）。 相似文献
8.
In order to separate ZSM-5 zeolite powders from solution easily, a series of magnetic ZSM-5 zeolites were prepared by hydrothermal synthesis with the addition of magnetic Fe3O4 panicles during the crystalline process. The products were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, infrared （IR） spectrum, energy dispersive X-ray （EDX）, specific surface area, magnetic susceptibility and adsorption capability. It was found that the magnetic ZSM-5 zeolites had good magnetism and the magnetic susceptibility increased with the increasing amount of Fe3O4 panicles. Compared with the pure ZSM-5 zeolite, the adsorption capability of magnetic ZSM-5 zeolites was acceptable. When the magnetic zeolites were used to adsorb Pb^2＋ from solution, the magnetic zeolite powder could be conveniently separated with magnetic separation technology. 相似文献
9.
In2O3 Ultrafine Powder Synthesis by Sol—Gel Method 总被引：1，自引：0，他引：1
The precursor of ultrafine In2O3 powder was prepared by the hydrolysis,peptization and gelation of InCl3.4H2O used as raw material.After calcination,ultrafine In2O3 powder was obtained.The particles were characterized by the methods of thermo-gravimetric and differential thermal analysis(TG-DTA),X-ray diffractometry(XRD) and transmission electron microscopy(TEM).respectively. 相似文献
10.
王立奎 《浙江工贸职业技术学院学报》2008,8(2)
综述了合成氨工业催化剂从Fe3O4基到Fe1-xO体系和钌催化剂的发展,表明Fe1-xO催化剂体系的发明,使氨合成催化剂的活性有了长足的进步,而钌催化剂有望突破近一个世纪的铁催化剂的历史。结合氨合成的发展现状,提出合成氨催化剂的发展建议。 相似文献
11.
1 Introduction Alumina membrane has received considerable atten-tion for its thermal ,chemical and mechanical stabilityin filtration applications .Alumina membraneis usuallyprepared by sol-gel process ,in which uniform nano-meter-sized particles can be pr… 相似文献
12.
Alumina membranes without pinholes and cracks were prepared by the sol-gel process using anunordum aluminium sulphate as the starting material. The effects of different preparing conditions on morphology characteristics of the membrane were investigated by scanning electron microscopy and 3D rotational microscopy. The preparing conditions include the amounts of drying control chemical additives （DCCA）, sintering procedure and sol-gel concentration. The results showed that PVA is a good crack-preventing reagent and the morphology of supported membranes was affected by ninny factors, including Al2O3 concentration, PVA/Al2O3 ratio, heating rate, membrane thickness and intrinsic defects of the substrate surface. 相似文献
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1IntroductionSemiconductor metal oxides as chemical sensingmaterials have been extensively studied for a longti medue to their advantageous features,such as good sen-sitivity to the ambient conditions and si mplicity infabrication[1].Among them,it has bee… 相似文献
14.
In2O3 nanoparticles were prepared from or with different indium salts by chemical precipitation under the conditions of various pH values. The crystal structure and ceramic microstructure of the samples were characterized by X-ray diffraction （XRD） and transmission electron microscopy （TEM）. The results show that the mean grain size of In2O3 is less than 100 nm, and their particle homogeneity and dispersibility are satisfactory. The gas sensitivity defined as Ra/Rg was detected in a static system. The results show that the sensors made by as-prepared nanoparticles has high sensitivity to many gases such as alcohol, HCHO, NH3 , et al. The response time is less than 20 s and the recovery time is lower than 30 s. 相似文献
15.
林小英郑琴琴裴义山张丽琴梁壮玲张明珍 《福建工程学院学报》2017,(1):1-4
以硝酸钾为中心金属离子,1,4-苯二甲酸（H2BDC）、1,3,5-苯三甲酸（H3BTC）及混合物（H2BDC+H3BTC）为有机配体,N,N-二甲基甲酰胺（DMF）为溶剂,采用溶剂热法合成三种K-MOF晶体。通过X射线粉末衍射(PXRD)、红外光谱(FT-IR)、扫描电镜（SEM）及热重(TG)等方法对样品进行表征,考察不同配体对K-MOF的影响。结果表明:K+与H2BDC配位得到的长条状晶体,与H3BTC配位得到粉末状晶体,H2BDC与H3BTC同时存在时,K+优先与H3BTC配位得到粉末状晶体。K-MOF具有良好的热稳定性,在350℃内能保持结构的热稳定性。 相似文献
16.
通过三个实验的对比研究得出结论,退火温度Ta、退火加热速度、外加磁场的强度、外加磁场的频率以及纳米晶合金材料的工作温度等外界条件都是影响纳米晶Fe73.5Cu1Nb3Si13.5B9合金微观结构相和软磁特性的因素。其中退火温度是决定性的因素。同时表明,工作温度也是决定纳米晶合金软磁性能优劣和稳定的先决条件。 相似文献
17.
用化学共沉淀法合成出平均粒径在40-50nm的NdxFc_(3-x)O_4纳米晶,用TEM和PSD及XRD分析其结构、粒径和形貌.用磁天平和交流性自动测量仪研究其磁性能.结果表明,NdxFc_(3-x)O_4纳米晶是尖晶石结构,晶粒为立方形.比饱和磁化强度虽比相同制备条件下的Fe_3O_4略小,但矫顽力比Fe_3O_4高50%左右. 相似文献
18.
纳米晶铝酸锌的合成及表征 总被引：1，自引：0，他引：1
以硬脂酸法合成了纳米晶铝酸锌并用TG—DTA，XRD和TEM对其进行了表征．结果表明，纳米晶粒径小，粒度均匀，且呈尖晶石结构；纳米晶的粒径随烧结温度的变化而变化． 相似文献
19.
采用速凝法制备NdFeB薄带,再经氢破制粉、压型、烧结、热处理制备NdFeB永磁体,通过激光粒度分布仪、光学显微镜以及AMT-4磁学特性测量仪等手段表征磁体的组织和性能,考察气流磨工艺对磁体组织和性能的影响规律.研究结果表明:气流磨分选转速越快,磁粉粒度越细小,制备磁体的磁学性能先增加后减小,当气流磨分选转速为3 400 r/min时,制备磁体组织均匀,剩磁、矫顽力、最大磁能积分别达到14.19 kGs、907.44 kA/m和397.28 kJ/m3. 相似文献
20.
Ferrospheres in fly ashes from a coal-fired power plant were extracted by a magnetic separation technique and their microstructure was studied by scanning electron microscopy （SEM）, energy dispersive X-ray analysis （EDX） and environmental scanning electron microscopy （ESEM）. Ferrospheres in fly ashes show significant iron enrichment compared to their respective fly ashes. Iron oxides in ferrospheres mainly occur as minerals magnetite （Fe3O4） and hematite （α-Fe2O3）, which are derived mainly from the decomposition and oxidation of iron-bearing minerals in coal during combustion. EDX data indicate that ferrospheres also contain Si, S, Al and Ca resulting from quartz, mullite, anhydrite and amorphous materials. A large percentage of ferrospheres are commonly 5-50 μm in size. The microstructure of ferrospheres includes smooth, polygonal, dendritic, granular and molten drop characteristics. SEM coupled with EDX provided fast and accurate results of the microstructure and chemical composition of ferrospheres, and helped us to assess environmental issues related to the disposal and utilization of fly ashes. 相似文献