一种制备磁性Co纳米颗粒的新方法

采用创新的、特殊的实验方法,实现在液相化学反应中精确控制磁性纳米颗粒的生长过程:将物理与化学方法相结合,在传统的液相化学反应的基础上引入物理作用,达到对磁性纳米颗粒生长大小的控制.对其形状和大小进行了透射电镜分析,确认Co纳米粒子为球形,平均粒径为14nm.并对其磁特性进行了初步测试分析.     

液相高分子保护纳米粒子形状可控制备研究进展

由于纳米材料具有极小的粒径,因而其性质与大粒径本体材料的有很大的区别,近年来发现纳米粒子的形状也是影响其材料性能的重要因素.各种具有特殊形状纳米粒子的合成及其形状控制机理的研究正受到越来越多学者的关注.就这方面的研究进展作一综述.     

聚琥珀酰亚胺纳米粒子的制备及粒径调控

采用聚琥珀酰亚胺(PSI)作为原料,利用PSI易溶于N,N-二甲基甲酰胺(DMF)却不溶于水的性质来制备PSI纳米粒子。利用动态光散射与紫外可见分光光度计等手段对所制备的纳米粒子进行了表征,并通过正交试验来分别讨论PSI溶液浓度,PSI溶液体积,水体积及流量对纳米粒子的粒径大小以及粒径分布(PDI)的影响。结果表明:PSI溶液浓度是影响纳米粒子粒径大小和分布的主要因素。     

MPCVD法制备低粒径纳米金刚石薄膜的研究

采用微波等离子体化学气相沉积法,以Ar/H2/CH4为气源,通过改变气源流量比例和功率,探究生长低粒径纳米金刚石的最佳条件。利用X射线衍射仪和扫描电子显微镜分别对制备出的薄膜的晶粒尺寸和表面形貌进行了表征,并采用拉曼散射光谱仪对薄膜的质量及残余应力进行了分析。结果表明:氩氢浓度比例相对于功率和甲烷浓度等因素对金刚石粒径影响较大;随着氩氢浓度比例增大,金刚石粒径呈减小趋势;金刚石相对于石墨相的含量先减小后增大,且由拉曼G峰引起的拉应力不断增大;膜表面的团聚体尺寸逐渐减小,平整度随之提升。     

纳米粒子粒径的测量研究

采用X射线衍射法(谢乐法)与透射电子显微镜法(TEM法)对纳米粒子粒径的测量进行了研究。结果表明,该两种方法都可用于纳米粒子粒径的的测量与表征,且两者的测量结果相当一致;纳米粒子实际平均粒径似应在两种方法测定结果之间。     

液相法制备纳米镍粉研究进展

详细介绍了液相法制备纳米镍粉的研究进展,并对液相法制备纳米镍粉的一些影响因素进行了探讨,例如反应物和还原剂的浓度、温度、表面活性剂等。对比分析了一些制备方法的特点,同时简单地介绍了纳米镍粉的应用前景和发展趋势。     

模板法制备纳米片状银粉的粒径与形貌控制

模板合成法广泛应用于纳米材料的研究.表面活性剂在水溶液中可以形成多种自组装胶体结构,被认为是纳米材料制备的有效模板,对非球形贵金属纳米粉体的制备很有效.对片状银粉的制备方法进行了总结,特别是纳米片状银粉的模板法制备,探讨了模板法制备纳米片状银粉的原理与影响因素,分析了模板法制备纳米片状银粉的粒径与形貌控制关键,并对纳米片状银粉粒径与形貌控制提出了一些建议.     

液相法制备纳米镍粉研究进展

详细介绍了液相法制备纳米镍粉的研究进展．并对液相法制备纳米镍粉的一些影响因素进行了探讨．例如反应物和还原剂的浓度、温度、表面活性剂等。对比分析了一些制备方法的特点．同时简单地介绍了纳米镍粉的应用前景和发展趋势。     

激光蒸凝法制备氧化铜纳米粒子

以１５０Ｗ ＣＷ ＣＯ_２激光器为光源,Ｃｕ（ＡＣ）_２·Ｈ_２Ｏ为靶材,采用激光蒸凝法制备出了氧化铜纳米粒子．初步研究了反应参数对纳米粒子性能的影响,并用Ｘ射线衍射、电子衍射、透射电镜等技术对纳米粒子的性能进行了表征,同时对纳米粒子的形成机理进行了初步的探讨．实验结果表明;激光功率密度、反应压力、载气种类及流量等工艺参数对产品的粒度、晶型等性能均有影响．在惰性气氛下,产物主要是Ｃｕ和Ｃｕ_２Ｏ,粒径为１０～３０ｎｍ;在氧气气氛下,产物主要是Ｃｕ、Ｃｕ_２Ｏ和ＣｕＯ的混合物,粒径为１０～５０ｎｍ．     

有机溶胶法制备超细钴纳米粒子的研究

以乙二醇为溶剂、柠檬酸钠为络合剂、甲酸钠为还原剂,采用有机溶胶法制备得到粒径为2nm的单分散超细钴纳米粒子.XRD分析表明,所得钴纳米粒子为六方密堆积(hcp)晶型,XPS结果显示,钴纳米粒子表面没有被氧化.研究发现,使用温和的还原剂甲酸钠和较高黏度的溶剂乙二醇有助于得到超细钴纳米粒子.     

A photochemical method for controlling the size of CdS nanoparticles

The optical and electrical properties of semiconductor nanoparticles are strongly dependent on their size. A flexible control of the size of the nanoparticles is of interest for tuning their properties for different applications. Here we use a coupled method to control the size of CdS nanoparticles. The method involves the photochemical growth of CdS nanoparticles together with the use of a capping agent as an inhibiting factor. CdS nanoparticles were formed through a photoinduced reaction of CdSO(4) and Na(2)S(2)O(3) in an aqueous solution. Mercaptoethanol (C(2)H(6)OS) was used as the capping agent, and we investigated the effect of illumination time, illumination intensity and the concentration of capping agent on the nanoparticle size. Transmission electron microscopy (TEM) shows crystalline nanoparticles with relatively low dispersion. Optical absorption spectroscopy was mainly used to measure the band gap and size of the nanoparticles. Increasing the illumination time or illumination intensity increases the nanoparticle size, while higher capping agent concentration leads to smaller nanoparticle size. A band gap range of 2.75-3.4?eV was possible with our experimental conditions, corresponding to a 3.2-6.0?nm size range.     

多元醇法制备CoNi纳米粒子的形成机制,尺寸控制及磁性能

采用多元醇法在150～190℃合成了CoNi合金纳米粒子,利用SEM-EDX,XRD和VSM对所制备的CoNi纳米粒子形貌、成分、结构以及磁性能进行了研究,并进一步探讨了形核剂K2PtCl4对CoNi纳米粒子形貌及磁性能的影响。结果表明,在180℃用多元醇法制备的Co40Ni60(inat%)纳米粒子为FCC结构,Co2+要易于Ni2+被还原,导致最初10min内合成的CoNi纳米粒子中含有约78%(原子分数)Co,表现为高饱和磁化强度和高矫顽力,随着反应时间的延长,CoNi纳米粒子的Co含量、饱和磁化强度及矫顽力逐步下降。在150～190℃范围内,随着反应温度的提高,Ni2+的被还原能力增强,高温下合成的CoNi纳米粒子具有较低的饱和磁化强度和较小的矫顽力。形核剂K2PtCl4的加入,并不影响CoNi合金纳米粒子的成分和晶体结构。但是,随着形核剂浓度的增加,CoNi纳米粒子平均直径明显减小,其矫顽力有所增大。通过设计形核剂的浓度,CoNi纳米粒子的直径可以在96～580nm范围内任意控制。     

Effects of surfactants on size and structure of amylose nanoparticles prepared by precipitation

The present work investigated the influence of surfactants on size and structure of amylose nanoparticles (ANPs) prepared through precipitation. ANPs were fabricated using absolute ethanol containing surfactants (Tween80, Span80 and mixtures of Tween80 and Span80 with ratios of 25/75, 50/50 and 75/25, respectively) as non-solvents. The obtained ANPs were characterized using dynamic light scattering (DLS), scanning electron microscopy and X-ray diffraction. The results showed that surfactant type, concentration and hydrophilic–lipophilic balance (HLB) value had great impact on size of precipitated ANPs. The smallest ANPs with mean size of 155 nm determined by DLS were obtained by using 0.5% (in proportion of the amylose solution volume) of Tween80/Span80 mixture (HLB = 12.33). The precipitated ANPs possessed the V-type crystalline structure no matter whether using the surfactants or not.     

微生物合成金属纳米粒子研究进展

当前金属纳米粒子主要采用物理和化学方法合成，但微生物也能合成金属纳米粒子，与常规方法相比，微生物合成金属纳米粒子不仅可大量减少还原剂的用量和降低能源成本，而且不污染环境。综述了国内外使用微生物合成金属纳米粒子的研究进展。     

Effect of bismuth on the properties of Mn ferrite nanoparticles prepared by co-precipitation method

Nanoparticles of MnBi_xFe_2−xO₄(x = 0.0, 0.02, 0.04, 0.06) have been synthesized by a chemical co-precipitation method. X-ray diffraction analysis (XRD) reveals that bismuth exits in its Bi³⁺ and Bi⁵⁺ state. It was also observed that bismuth substitution enhances the grain growth and density. The dielectric constant (ε′) and the loss tangent (tan δ) increases with increase in bismuth content. Resistivity (ρ) and maximum magnetization (M) was found to decrease with increasing bismuth content.     

Photoluminescence of ZnO nanoparticles prepared by a low-temperature colloidal chemistry method

ZnO nanoparticles have been synthesized by a low-temperature colloidal chemistry method using ethylene glycol as the reaction medium. Crystalline ZnO nanoparticles were formed at a temperature as low as 150 °C. The crystallite size of the ZnO nanoparticles ranged from 8 to 20 nm. The synthesized ZnO nanoparticles exhibited size-dependent photoluminescence. Photoluminescence of the ZnO nanoparticles depended largely on the post-annealing temperature. Both DL and UV emissions were suppressed at a lower post-annealing temperature of 300 °C; however they were recovered at a higher annealing temperature of 900 °C.     

电子束辐照法合成钴纳米粒子的表征

本文论述了在常温常压、无任何催化剂的条件下,通过电子束辐照制备纳米钴。利用X射线衍射仪（XRD）、透射电子显微镜（TEM）和差热分析仪（DSC）分别分析了纳米钴的结构、行貌、大小和熔点。利用激光散射粒度分布仪（LSPSDA）观察了纳米钴的粒度分布,并用样品振荡磁力计（VSM）分析了纳米钴的磁性。结果表明实验所制得的纳米钴粒子平均粒径32nm,粒度分布窄,熔点显著降低。最后,探讨了纳米钴的形成机理。     

Thermal stability of silica-coated magnetite nanoparticles prepared by an electrochemical method

Magnetite nanoparticles have been prepared by electrooxidation of iron in water. Surface modifications have been conducted by coating the nanoparticles with silica by a one-step synthesis in dilute sodium silicate solution. The mean size of particles was approximately 10–30 nm for the uncoated particles and 9–12 nm for the coated particles. The results obtained from thermal gravimetric/differential thermal analysis (TG/DTA) revealed that the silica layer formed by the electrochemical method was stable and could serve as a protective layer. Annealing the nanoparticles at 550 °C for 30 min converts magnetite into maghemite for the silica-coated particles, and it further converts the uncoated particles into hematite. The conversions cause the saturation magnetization to decrease for all samples.