Study of the structural features of ε-Co nanoparticles synthesized by cobalt carbonyl decomposition in the presence of surfactant

Cobalt nanoparticles (3–7 nm in size) obtained by cobalt carbonyl decomposition in 1,2-dichlorobenzene in the presence of surfactants (trioctylphosphine oxide and oleic acid) have been studied by a complex of structural methods: small-angle X-ray scattering, electron diffraction, and transmission electron microscopy. The nanoparticles synthesized are found to consist of the cubic ε-Со phase; their crystal structure is described within the sp. gr. P4₁32, a = 6.097 Å. Using small-angle X-ray scattering, the size and shape of nanoparticles have been determined directly in the liquid dispersion. Most of the particles have a spherical shape; their average size is ≈3.5 ± 0.5 nm, which agrees with the electron microscopy data. Possible factors causing the ε-phase formation during synthesis of metallic Co nanoparticles are discussed.

     

Structural properties of silicon nanoparticles formed by pulsed laser ablation in liquid media

Silicon nanoparticles have been formed as a result of the irradiation of single-crystal silicon targets in distilled water and liquid nitrogen, by, respectively, picosecond and femtosecond laser pulses. The main structural properties of these nanoparticles have been investigated by atomic force microscopy, transmission electron microscopy, electron diffraction, Raman scattering, and photoluminescence spectroscopy. These particles are found to be mainly spherical. The presence of crystalline and amorphous silicon phases under picosecond ablation in water is established experimentally. Irradiation by femtosecond pulses in liquid nitrogen can yield nanoparticles smaller than 5 nm in size, which are quantum dots with a characteristic photoluminescence peak near 750 nm.     

TiOCl2溶液微波加热制备金红石型TiO2纳米粒子

本文报道了一种由TiOCl2液相直接合成金红石型TiO2纳米粒子的新方法,即微波诱导沸腾回流强迫水解法,用该法制备出常规条件下不能得到的产品.所得产物用粉末X射线衍射仪和透射电子显微镜表征,证明产物为金红石型,粒子尺寸5～30nm可控.研究表明,产物物相取决于Ti4+的初始水解速率,水解速率越快,越有利于金红石相成核;通过控制初始Ti4+的浓度,可改变纳米TiO2的粒径.另外还讨论了该金红石型TiO2纳米粒子的成核机理.     

A novel sonochemical synthesis and nanostructured assembly of polyvinylpyrrolidone-capped CdS colloidal nanoparticles

Nanoparticles of cadmium sulfide (nano-CdS) have been successfully prepared from an aqueous solution of cadmium chloride and sodium sulfide by a novel sonochemical method. Through adding polyvinylpyrrolidone K30 (PVP) as the dispersant, a yellow translucent colloidal solution of cadmium sulfide which was considerably stable within at least one month was obtained. The characterizations of nanoparticles by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM) and FT-IR spectroscopy showed good properties of small size, high surface area and crystal structure. The size of the prepared nanoparticles was about 3–5 nm according to XRD spectra and TEM images. Poly(diallyldimethylammonium chloride) (PDDA) has been employed to fabricate multilayer films on quartz wafer and indium tin oxide (ITO) electrode in a layer-by-layer manner. Atomic force microscopy (AFM) displayed the dense coverage of the substrate surface by the nanoparticles. UV–vis absorption spectroscopy confirmed the consecutive growth of PDDA/nanoparticles layer pairs. The photoelectrochemical and the electrochemical behaviors of the prepared CdS particle were examined as well.     

煅烧温度对湿化学法制备AlN粉体的影响

以六水合氯化铝和尿素为原料,甲醇为溶剂,在NH₃气氛下通过湿化学法制备AlN粉体,并采用X射线衍射仪、扫描电子显微镜和激光粒度仪对产物进行表征。结果表明:煅烧温度在900 ℃以上可获得六方AlN粉体;煅烧温度为1 000 ℃时获得的AlN粉体具有球形特征,粉体的平均晶粒尺寸为17.0 nm,平均粒径为159.5 nm。使用透射电子显微镜进一步表征了AlN粉体的微观结构。拉曼光谱结合能谱分析表明,存在于AlN粉体中的非晶杂质不是残留的含碳副产物,而是粉体表面水解产生的氢氧化铝。     

超顺磁Fe3O4纳米粒子的制备及弛豫性能

采用简单的共沉淀法制备聚丙烯酸包覆、良好亲水性的Fe3 O4纳米粒子,研究了不同Fe2+和Fe3+比例对所得纳米粒子的影响.高分辨率透射电镜和X-射线衍射分析证实所得产物为Fe3 O4,红外光谱分析和热重分析表明微粒表面成功包覆聚丙烯酸.纳米粒子的粒径大小和分布用透射电镜分析,平均晶粒大小用X-射线衍射分析.结果表明,Fe2+:Fe3+加入摩尔比1:1.5、1:1.75和1:2所得3个纳米颗粒的透射电镜分析平均粒径分别为7.2 nm、6.7 nm和8.3 nm,X-射线衍射分析平均晶粒大小分别为9.1 nm、8.2 nm和9.1 nm.激光粒度仪分析表明所得样品均含有部分大粒径的颗粒,应是颗粒出现部分团聚.磁性分析证实所得样品具有良好的超顺磁性.弛豫性能分析表明1:1.5样品适合用于T1造影剂,1:1.75和1:2适合用于T2造影剂.该研究可为磁共振造影剂的性能优化提供参考.     

Low temperature deposition of zinc oxide nanoparticles via zinc-rich vapor phase transport and condensation

ZnO nanoparticles as small as 80 nm were successfully synthesized using a modified vapor phase transport (VPT) process at substrate temperatures as low as 222 °C. Particle size distribution and morphology were characterized by scanning electron microscopy and atomic force microscopy. Energy dispersive X-ray spectroscopy and X-ray diffraction indicate the synthesis of high quality crystalline ZnO structures. Low temperature (4.2 K) photoluminescence (PL) spectroscopy was used to characterize the optical quality of the nanoparticles. Ultraviolet emission and a nanostructure specific feature at 3.366 eV are strong in the PL spectra. The 3.366 eV feature is observed to predominate the spectrum with decrease in particle size. This size effect corroborates the luminescence as a nanostructure-specific surface related exciton feature as previously speculated in the literature. In addition, self-assembled ZnO mesoparticles (>100 nm) were realized by increasing the growth time. Low growth temperatures of the particles allow for their potential utilization in flexible organic hybrid optoelectronics. However, this work focuses mainly on the modified synthesis and optical characterization of nanoparticles.     

硅基AAO模板内电化学沉积ZnO纳米线及其光电性能研究

本文利用二次阳极氧化法在p型低阻〈100〉晶向的硅衬底上制备了AAO/Si,以硅基AAO为辅助模板,采用电化学沉积的方法以Zn(NO3).6H2O和HMT(C6H12N4)为原料,在80℃的水浴槽中制备了ZnO纳米线结构。采用SEM,XRD和拉曼光谱等手段对ZnO/AAO/Si复合结构进行表征。SEM图表明ZnO纳米线已成功组装到AAO/Si模板里,直径约45 nm,长度约为600 nm。XRD和拉曼光谱表明ZnO具有六角纤锌矿多晶结构。光致发光(PL)谱图表明ZnO/AAO/Si复合结构在565 nm附近有较宽黄绿发射峰,在395 nm附近有微弱的紫外发射峰。场发射测试结果表明,ZnO纳米线的场增强因子的β值为2490,场增强因子很高,具有广泛的应用前景。     

Synthesis and spectral properties of starch capped CdS nanoparticles in aqueous solution

Synthesis of cadmium sulphide nanoparticles has been carried out in aqueous solution precipitation. Starch added during the synthesis of the nanoparticles resulted in cadmium-rich nanoparticles forming a stable complex with starch. The morphology and crystalline structure of such structures were measured by high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD), respectively. The grain size of the nanoparticles determined by these techniques was of the order of 5 nm, which correlates well with measurements performed by Raman scattering and photoacoustic spectroscopy.     

溶剂热法合成纳米结构四氧化三铁空心微球磁性研究

通过溶剂热反应合成了Fe3O4空心微球.采用X射线衍射仪(XRD)、透射电子显微镜(TEM)和扫描电子显微镜(SEM)对样品的结构和形貌进行了表征.结果表明,所制备的单分散Fe3O4空心微球为立方多晶结构,其直径约400 nm,是由约40 nm纳米颗粒组装而成.用振动样品磁强计(VSM)测量了Fe3O4空心微球的室温和变温磁性.室温磁滞回线表明不同反应时间所得产物均表现为良好的亚铁磁性,其饱和磁化强度Ms随反应时间的增加先升后降.由反应时间为12 h所得的Fe3O4空心微球在1000 Oe下的M-T曲线测得其居里温度为778 K,并测得其在外磁场H=5000 Oe场冷却至液氮温度再升至不同温度(100 K,200 K,300 K)时的磁滞回线,发现不同温度时测得的Fe3O4空心微球磁滞回线都是左右对称的,没有明显的交换偏置效应,且随测量温度增加,其饱和磁化强度Ms和矫顽力Hc均降低.     

溶剂热合成氮化硼纳米晶过程中氮源种类的影响

以NaNH2和BC l3为原料,利用溶剂热方法合成了六方氮化硼纳米微晶,并用红外吸收光谱(FTIR)、X射线粉末衍射(XRD)方法分析了微粒的结构,利用透射电子显微镜(TEM)观测了BN微粒的粒度和微观形貌。与早期用L i3N为氮源合成的氮化硼(产物中具有较多纳米棒)相比,本文中制备的氮化硼纳米晶主要呈球形,颗粒粒度明显增大,而且产率有较大幅度的提高。     

不同晶相草酸钙晶体的选区电子衍射和X射线衍射比较分析

在卵磷脂-水脂质体中制备了一水草酸钙(COM)、二水草酸钙(COD)和三水草酸钙(COT).并对它们分别进行了透射电镜(TEM)、选区电子衍射分析(SAED)和X射线衍射(XRD)分析.TEM结果表明,COM、COD和COT均为泡状,粒径约80～150nm.将SAED结果与XRD结果对比分析,发现将SAED图谱指标化后所得的衍射数据与XRD的特征峰值基本相符,但在相对强度上存在差别.本实验结果表明,将TEM、SAED和XRD技术联合分析纳米级草酸钙晶体,不但可以观察纳米级草酸钙的形貌,而且能对其晶相、单晶和多晶等进行深入的了解.     

土豆基碳量子点的制备、Mn掺杂及在Ag+检测中的应用

以土豆为碳源采用水热法合成了发光碳量子点(CQDs),向体系中加入碳酸锰,合成了锰掺杂的CQDs(Mn-CQDs)。用透射电镜、X射线衍射仪、X射线光电子能谱、紫外-可见吸收光谱、荧光光谱、红外光谱等对样品进行了表征。结果表明:CQDs和Mn-CQDs为球状,平均粒径3~5 nm;Mn掺杂增强了CQDs的荧光强度及稳定性;CQDs和Mn-CQDs最大激发波长分别为435 nm、395 nm,对应的发射波长分别为525 nm、465 nm。将CQDs、Mn-CQDs用于金属离子检测,它们都对Ag⁺具有很好的选择性,对Ag⁺的检测限分别为0.064 μmol/L、0.027 μmol/L,表明CQDs、Mn-CQDs可应用于水介质中Ag⁺的痕量检测,Mn-CQDs具有更高的灵敏度。     

超临界水中制备FeIn_2S_4纳米颗粒

采用硫代乙酰胺(TAA)、三氯化铁和四氯化铟为原料,超临界水为反应介质,用简单的一步法成功地合成出了FeIn_2S_4纳米颗粒.利用粉末X射线衍射(XRD)、扫描电子显微镜(SEM)以及透射电子显微镜(TEM)等手段对产物进行了表征.实验结果表明,所得产物为立方相的、面心晶格结构的FeIn_2S_4,电镜结果显示FeIn_2S_4纳米颗粒具有片状形貌,颗粒大小在50～100 nm之间,并具有较好的分散性.     

Determination of the size and phase composition of silver nanoparticles in a gel film of bacterial cellulose by small-angle X-ray scattering,electron diffraction,and electron microscopy

The nanoscale structural features in a composite (gel film of Acetobacter Xylinum cellulose with adsorbed silver nanoparticles, stabilized by N-polyvinylpyrrolidone) have been investigated by small-angle X-ray scattering. The size distributions of inhomogeneities in the porous structure of the cellulose matrix and the size distributions of silver nanoparticles in the composite have been determined. It is shown that the sizes of synthesized nanoparticles correlate with the sizes of inhomogeneities in the gel film. Particles of larger size (with radii up to 100 nm) have also been found. Electron microscopy of thin cross sections of a dried composite layer showed that large particles are located on the cellulose layer surface. Electron diffraction revealed a crystal structure of silver nanoparticles in the composite.     

Production and Study of Silver Nanoparticles by 532 nm Laser Pulse Ablation in NaCl Solution

In this experimental research, silver nanoparticles are produced in NaCl solution by the laser ablation method. Our aim was to investigate the effect of the amount of NaCl in the ablation medium on the characteristics of nanoparticles. A 7 ns pulsed Neodymium YAG laser (Nd:YAG) at 5 J/cm2 fluence and 532 nm wavelength was employed to produce Ag nanoparticles in distilled water with four different concentrations of NaCl. The optical properties, size distribution, and agglomeration of nanoparticles were investigated by several diagnostics. The UV–Visible absorption spectra of the Ag nanoparticles exhibit absorptions in the UV region because of surface plasmon resonance. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to study the size distribution and morphology of nanoparticles. Dynamic light scattering (DLS) was employed to measure the hydrodynamic size of nanoparticles in suspensions. With X-ray diffraction (XRD) pattern, the lattice structure of nanoparticles was studied. Fourier transform infrared (FTIR), photoluminescence (PL) spectra were obtained to observe the molecular structure and atomic energy levels of particles.     

Green synthesis of metal sulfide nanocrystals through a general composite-surfactants-aided-solvothermal process

In this paper, we developed a generalized and greener composite-surfactants-assisted-solvothermal process (CSSP) to produce colloidal nanoparticles of metal sulfides. X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectra (XPS) revealed that single-molecular-layer type of MoS₂ nanoparticles with diameter 6–10 nm were successfully synthesized. The molecular structure model of the capped MoS₂ nanoparticles was suggested through further examination by infrared spectra. Hexagonal CdS nanocrystals with spherical, triangle, and hollow sphere shapes were controllably synthesized by varying the experimental conditions. A possible in-situ reduction–sulfidation mechanism was proposed for the formation of Ag₂S nanocrystals, where the metal ions were reduced to metallic nanoparticles before the generation of sulfides. The obtained nanocrystals through this CSSP approach could provide the building blocks for the bottom-up approach to nanoscale fabrication in nanoscience and nanotechnology.     

直流电弧等离子体制备NiO纳米颗粒研究

采用直流电弧等离子体技术成功制备了NiO纳米颗粒,并利用X射线衍射(XRD)、透射电子显微镜(TEM)和相应选区电子衍射(SAED)、傅里叶变换红外光谱(FTIR)、BET氮吸附等测试方法对样品的成分、形貌、晶体结构、比表面积、粒度分布、红外吸收性能进行表征分析.实验结果表明:直流电弧等离子体制备的NiO纳米颗粒为fcc结构的晶态,形貌呈规则的球形,粒度均匀,分散性良好,粒径范围在15～45 nm,平均粒径为25 nm,比表面积为33 m2/g.与普通块体NiO相比,红外吸收峰发生了红移.     

Synthesis and magnetic properties of monodisperse Fe3O4 nanoparticles with controlled sizes

Monodisperse magnetite nanoparticles coated with organic ligands have been chemically synthesised by using the poliol method. Modifying the synthetic conditions, particle diameter can be tuned from 3.5 to 7.1 nm. In order to investigate the critical size effects on the magnetic behavior of the samples, Fe₃O₄ nanoparticles have been fully characterized by X-ray diffraction, thermogravimetric analysis, transmission electron microscopy, SQUID magnetometry and electron paramagnetic resonance spectroscopy.     

PEG对纳米BaMgAl10O17:Eu2+蓝色荧光粉颗粒形貌及其发光性能的影响

以聚乙二醇(PEG)为改性剂,采用溶液燃烧法成功制备了准球形的PDP用BaMgAl10O17:Eu2+(BAM)蓝色荧光粉.通过X射线粉末衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)以及荧光光谱对获得的试样进行了表征.结晶表明,获得的BAM荧光粉颗粒为准球形、颗粒尺寸为20～40nm.当PEG的分子量(MW)为10000且质量百分比浓度为5.0;时,能获得最佳形貌和最高发光强度的BAM蓝色荧光粉.