超顺磁单分散性Fe3O4磁纳米粒的制备及性能表征

具有超顺磁单分散性的Fe₃O₄磁纳米粒在生物医学材料领域有着广泛的用途. 本研究在水、乙醇和甲苯混合体系74℃回流的条件下制备了具有超顺磁性的表面含油酸的Fe₃O₄磁纳米粒,研究了制备过程中OH^-浓度的变化对磁纳米粒的表面性能、粒径、分散性及磁性能的影响, 并对其机理进行了初步探讨. 采用XRD、FTIR、DLS、TEM和VSM等手段对制备的磁纳米粒进行表征. 结果表明, 当NaOH/Fe(Ⅱ)摩尔比＜8时, Fe₃O₄磁纳米粒表面含油酸可良好地分散于非极性溶剂中, NaOH的加入对磁纳米粒的粒径和饱和磁化强度等性能无明显影响;而当NaOH/Fe(Ⅱ)摩尔比≥8时, Fe₃O₄磁纳米粒仅能分散于水等极性溶剂中, 饱和磁化强度虽可增至40A·m²/kg, 但为多分散且易团聚.     

钛掺杂的α-Fe2O3-K2O纳米湿敏陶瓷结构与性能研究

采用硬脂酸凝胶法新工艺在α－Fe₂O₃－K₂O复合体系中掺入TiO₂.XRD、BET比表面吸附、Archimede排水法等手段对掺钛α－Fe₂O₃－K₂O纳米陶瓷分析表征结果表明,适量掺杂TiO₂,材料仍保持α－Fe₂O₃的刚玉结构,且具有很高的热稳定性,但抑制了主晶相晶粒成长,增大了材料比表面积及孔隙率．电性能及湿敏特性测试结果表明,适量掺杂TiO₂,降低了材料固有电阻,显著减小了材料湿滞;认为钛掺杂使材料晶粒细化;从而使K+更加分散地沉积在α－Fe₂O₃晶粒表面非晶壳层中,是改善材料湿滞的主要原因．     

CrO3对Fe2O3+Al铝热反应系统反应过程的影响

用铝热-重力分离法制备了不含铁铝尖晶石（FeAl₂O₄）的陶瓷内衬复合钢管,并通过热力学计算分析了有关反应的优先顺序,结果表明,在Fe₂O₃+Al系统中强氧化剂CrO₃与Al的反应并不是一步完成而是分步反应,FeAl₂O₄优先于Cr₂O₃与Al反应,因而加入CrO₃添加剂可有效地去除陶瓷层中的尖晶石相,从而提高复合钢管的耐蚀性能.     

油酸钠基纳米Fe3O4磁流体制备、表征及应用

采用化学共沉淀法制备了Fe3O4磁性纳米粒子。以油酸钠为基体的Fe3O4磁流体具有良好的分散效果。利用X衍射仪（XRD）和透射电镜（TEM）分别对磁性粒子的物相、结构及粒径进行了分析，证实其为纯相Fe3O4粒子且粒径约为8nm。采用振动样品磁强计（VSM）测得包覆油酸钠前后的Fe3O4粒子饱和磁化强度（Ms）分别为60...     

高温多元醇法制备超顺磁CoFe2O4纳米颗粒磁共振造影剂

以FeCl₃·6H₂O、CoCl₂·6H₂O和HOOC-PEG-COOH为反应物, 利用高温多元醇法制备了核心粒径为5~10nm的超顺磁CoFe₂O₄纳米颗粒, 样品在水溶液中具有良好分散性. 通过改变修饰剂的种类和用量、反应温度及反应时间可以对纳米颗粒的尺寸、水中分散性及磁性能产生影响. 研究表明：选用带有强极性基团的修饰剂, 增加修饰剂的用量, 提高反应温度和延长反应时间, 可以增大颗粒的尺寸, 改善颗粒的分散性, 窄化粒径分布. 实验获得的最佳生长条件为：金属盐总量与修饰剂质量比为1∶10, 在210~220℃之间反应2h. 磁性能研究表明所得样品在室温下具有超顺磁性, 其饱和磁化强度与尺寸有关.     

添加Y2O3-Dy2O3的AlN陶瓷的烧结特性及显微结构

本文探索了以自蔓延高温（SHS）法合成并经抗水化处理的AlN粉为原料,以Y₂O₃－Dy₂O₃作为助烧结剂的AlN陶瓷的烧结特性及显微结构．结果表明,晶界处存在Dy₄Al₂O₉、Y₄Al₂O₉、DyAlO₃、Dy₂O₃和DyN等第二相物质,随烧结温度变化,第二相的种类、数量和分布不同,显微结构也随之变化,从而影响AlN的热导率．在1850℃下,可获得热导率为148W／m·K的AlN陶瓷．     

在氧气中焙烧C/γ-Al2O3复合物快速制备α-Al2O3微粉

提出了一种快速制备α-Al₂O₃微粉的方法, 以淀粉为碳源、γ-Al2O₃为前体制备了C/γ-Al₂O₃复合物, 然后在800℃、氧气氛中焙烧制备α-Al₂O₃微粉. N₂物理吸附及SEM分析结果表明, 所制得的α-氧化铝颗粒细小, 约为2μm. 该方法具有焙烧温度低、焙烧时间短的优点, 同时, 淀粉及γ-Al₂O₃均为廉价的工业原料, 且该方法所需淀粉量较少, 最少仅需0.3g/g γ-Al₂O₃, 对应的C/γ-Al₂O₃复合物碳含量约为6wt%, 因而极具工业化应用前景.     

二步煅烧法制备超细α-Al2O3粉

经由二步煅烧法制备了超细α- Ａｌ_２ Ｏ_３ 粉 Ｘ Ｒ Ｄ 分析说明所制备的粉是α相, Ｔ Ｅ Ｍ 观察到其一次粒子尺寸在８０ ～１００ｎｍ 间, 形貌较规则     

ZnO-Al2O3混合粉体水基悬浮液性能的研究

通过Zeta电位、粘度、沉降等测试,研究了添加剂含量、pH值、固含量和球磨时间对ZnO-Al₂O₃混合粉体水基悬浮液的稳定性、流动性等的影响.实验结果表明：当pH值为9左右,聚丙烯酸添加质量分数为0.20%时,悬浮液粘度最低、稳定性最好.可制得固相体积分数55%的悬浮液.聚乙二醇添加量的增加,使悬浮液粘度增大、稳定性下降.该实验条件下,球磨时间以40h为佳.     

氧化物电子陶瓷微波烧结用保温材料MgAl2O4-LaCrO3的研究

报道了一种用于氧化物电子陶瓷微波烧结的保温体材料MgAl₂O₄-LaCrO₃的研究和应用情况.该保温材料解决了许多氧化物电子陶瓷在微波烧结过程中易发生的热应力开裂问题并同时具有使样品均匀烧结成瓷的作用.现已成功地应用该保温体对CoMnNiO系NTC热敏材料;BaTiO₃系PTC材料,ZnO掺杂系电压敏材料,LaCrO₃基复合材料等氧化物电子陶瓷进行了微波烧结,烧结样品无热应力开裂并成瓷均匀致密.适用的氧化物电子陶瓷微波烧结温度区间最高可至1600℃.     

超顺磁性纳米Fe_3O_4颗粒感生的横向弛豫

通过研究由SPIO(superparamagnetic iron oxide)和USPIO(ultrafine SPIO)引起质子的横向弛豫,发现SPIO体系中质子横向弛豫时间(T2)对检测等待时间有很强的依赖性。实验证明只有把等待时间外推到0所得到的T2_0才能够用于T2与浓度间关系的研究。最后分析了造成这一现象的原因。     

Bioinspired Superhydrophobic Fe3O4@Polydopamine@Ag Hybrid Nanoparticles for Liquid Marble and Oil Spill

Fe₃O₄ nanoparticles (NPs) with Ag NPs evenly distributed on the surface are fabricated by using polydopamine (PDA) as the intermediate layer. Silanization and thiol chemistry are used to firmly combine the Fe₃O₄@ PDA core and outer surface Ag NPs. The spherical and hybrid nanoparticles are termed Fe₃O₄@PDA@Ag NPs, which possess a core–shell and hierarchical structure. After surface modification with 1H,1H,2H,2H‐perfluorodecanethiol, the hybrid Fe₃O₄@PDA@Ag NPs become highly hydrophobic. Slight rolling of a water droplet on the as‐prepared NPs causes the formation of a “liquid marble”, which is capable of performing remote actuation on various solid surfaces, such as glass sheet, paper, plastic, textile, and ceramic, and at the liquid–air interface using a permanent magnet. Liquid marbles with self‐assembled NPs on the liquid surface have potential to act as a miniaturized reactor for manipulation of inner liquid droplet with high positioning precision. In addition, the Fe₃O₄@PDA@Ag NPs are multifunctional and can be applied for oil/water separation and antibacterial purpose.     

葡聚糖包覆纳米Fe3O4颗粒的研究

采用化学共沉淀法制备了葡聚糖包覆的纳米Fe3O4颗粒,平均粒径为6nm,包覆层厚度约为3～5nm,纳米Fe3O4粒径分布较窄.红外光谱分析可知,葡聚糖与纳米Fe3O4主要以氢键结合,结合Zeta电位和热重分析,分散作用主要是空间位阻作用,葡聚糖的包覆量约为10%.吸光度测试表明,随着葡聚糖用量的增加,悬浮液的稳定性提高.用量为25%时,悬浮液在室温下静止1周,无分层现象.包覆样的饱和磁化强度为60emu/g,具有良好的超顺磁性.     

磁性Fe3O4纳米颗粒的可控制备及生长研究

采用热法合成磁性Fe3O4纳米颗粒,通过精细调控实验条件能对其形状和大小进行有效控制。采用X射线衍射仪、透射电镜、振动样品磁强计等对Fe3O4纳米颗粒的成分、形貌及磁性等进行了表征测试。结果表明,Fe3O4纳米颗粒的饱和磁化强度为62.5emu/g。最后探讨了Fe3O4纳米颗粒的合成机理。     

Synthesis and Magnetic Properties of Fe3O4 Nanoparticles

Magnetic Fe₃O₄ nanoparticles with size below 10 nm have been prepared by the aqueous phase coprecipitation method. The Fe₃O₄ nanoparticles show typical superparamagnetism. Comparison is made between the dispersed sample and the powder sample, and the results are discussed.     

Structural and Magnetic Properties of Triethylene Glycol Stabilized Monodisperse Fe3O4 Nanoparticles

In this present study, a facile synthetic route was developed to prepare super-paramagnetic Fe₃O₄ MNPs directly via a one-pot approach. In this synthesis, only one iron containing compound and instead of high-boiling-point solvents, water-soluble tetraethylene glycol (TEG) was used as both the solvent and surfactant to control the particle growth and to prevent the aggregation of particles. Crystallite, particle, and magnetic core size are in good agreement with each other. The VSM measurement shows the superparamagnetic property of the product. The existence of TEG layer on the surface of the Fe₃O₄ nanoparticles was confirmed by Fourier transform infrared spectroscopy and thermal gravimetric analysis. The monodisperse morphology of the product was presented via TEM analysis. Due to the monodisperse morphology, superparamagnetic property, and small particle size, the product may have a potential application in biomedical research field.     

Effect of Carbon Shell on the Structural and Magnetic Properties of Fe3O4 Superparamagnetic Nanoparticles

Carbon-encapsulated iron oxides (Fe₃O₄/C) with a core/shell structure have been successfully synthesized by using a simple two-step hydrothermal method at 180 ^°C. Fe₃O₄ core nanoparticles were prepared by coprecipitation under two conditions. Synthesized nanoparticles were characterized by transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. TEM images and FTIR results prove that carbon coated iron oxide is formed and the estimated size for most of them is below 11 nm, which was consistent with the XRD result. The Williamson–Hall (W–H) method has been used to calculate crystallite sizes and lattice strain based on the peak broadening of the Fe₃O₄ and Fe₃O₄/C nanoparticles. The results of VSM imply that the Fe₃O₄ core and core–shell nanoparticles are superparamagnetic. The saturation magnetization of Fe₃O₄ and Fe₃O₄/C are 49 emu/gr and 40 emu/gr, respectively. The magnetic behaviors reveal that the amorphous carbon shell can decrease the saturation magnetization of Fe₃O₄ nanoparticles due to core–shell interface effects and shielding.