Morphologies of GdBO3:Eu3+ one-dimensional nanomaterials

Europium doped gadolinium orthoborate nanorods and nanoribbons were morphology-controlled grown on the porous anodic aluminum oxide (AAO) template surface via a hydrothermal process combined with high-temperature calcination. The morphologies, crystal structures and luminescent properties of the as-prepared nanomaterials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and photoluminescence (PL) spectra. The morphologies of the nanomaterials were controlled by the calcination temperature. If calcined at 1000 °C, the morphology of the GdBO₃:Eu³⁺ one-dimensional materials is nanorods; when calcined at 800 and 600 °C, the shapes of the Eu-doped GdBO₃ are nanoribbons. If treated at 900 °C, the as-prepared samples are composed of nanorods and nanoribbons.The changed morphologies of the as-prepared nanomaterials obtained from different calcination temperatures were explained according to the structural phase transition of GdBO₃. The PL spectrum shows that the characteristic emission of GdBO₃:Eu³⁺ one-dimensional nanomaterials is the ⁵D₀ → ⁷F₁ transition.     

不同结构磁性四氧化三铁纳米材料的介电特性和微波吸收性能

目的研究不同的纳米结构对Fe3O4纳米材料微波吸收性能的影响。方法采用水热法和高温碳热还原法,获得了纳米纺锤体、纳米管和开口空心球结构的三种磁性Fe3O4纳米材料,采用XRD、SEM和矢量网络分析仪研究了其物相、形貌和电磁特性。结果在这三种结构纳米Fe3O4材料中,空心球结构具有最小的介电常数和最高的波阻抗匹配系数,其磁损耗表现出双共振特性,且在7.5~14.3 GHz范围内,Fe3O4开口空心球的衰减系数明显高于另外两种结构的Fe3O4纳米材料,有利于拓宽材料的微波吸收带宽。在1.8~3.0 mm厚度范围内,Fe3O4开口空心球的反射损耗带宽均大于其他两种结构,在2.2 mm厚度下达到了5.0 GHz的有效吸收带宽(90%吸收),覆盖的频率范围为7.3~12.3 GHz。结论Fe3O4开口空心球由于特殊的结构而产生的双磁共振特性,增强了材料的微波衰减能力和阻抗匹配特性,其微波吸收能力明显优于纳米纺锤体和纳米管。经过超结构设计,可以实现宽带微波吸收。     

Fast Degradation of Green Pollutants Through Nanonets and Nanofibers of the Al-Doped Zinc Oxide

In this study, series of nanolayered structures of Zn–Al LDHs were prepared by urea hydrolysis. Nanofibers and nanonets of the Al-doped ZnO were formed via the decomposition of the nanolayers under high pressure and temperature. Nanospheres were also prepared for comparison. The different morphologies of the prepared nanomaterials were confirmed by several techniques. An improvement for the optical properties of the doped zinc oxides was observed through narrowing of their band gap energies because of transforming the nanolayers to nanonets and nanofibers. The photocatalytic activities of the prepared nanomaterials were studied through photocatalytic degradation of the pollutants of acid green dyes. Complete decolorization and mineralization of green dyes happened in the presence of the nanolayers and nanospheres within 4–6 h,while the nanonets and the nanofibers achieved the complete decolorization and degradation of the dyes at shorter time 1.3 h. These results could be explained though the kinetic study of the photocatalytic degradation of dyes. It was concluded that the nanonets and the nanofibers were very effective for the photocatalytic degradation of pollutants.     

A new class of approach for hybrid inorganic/organic materials containing semiconductor ZnO

A new route has been developed to prepare ZnO of various shapes using different thiophene acids and ZnO at suitable reaction. Nanosized hybrid materials have a diversity of well-defined morphologies, such as rod-like, star-like sample and particle. The structure and morphology changes of the as-prepared product were investigated by means of transmission electron microscopy (TEM), X-ray powder diffractometry (XRD), infrared spectrum (IR). The required thiophene acids have been prepared by using organometallic synthetic route and characterized by EI, ¹H NMR and photoluminescence (PL). The ZnO nanomaterials are expected to present special optical and electrical properties, and facilitate future nanoscale device application.     

硬质合金表面乙醇扩散火焰法沉积碳纳米材料的研究

本文采用乙醇扩散火焰法在原始态和酸蚀脱钴态硬质合金(WC-6%Co)上成功沉积出碳纳米材料,分别借助扫描电镜(SEM)、X射线衍射(XRD)、激光拉曼光谱(Raman)对其形貌和结构进行了表征。结果表明,原始态硬质合金上火焰沉积产物主要为纳米晶石墨,一步酸蚀脱钴态硬质合金上火焰沉积产物的中心区主要为球状超细金刚石、边缘区主要为超细金刚石和纳米晶石墨组成的复合碳纳米材料。     

锗基锂离子电池负极材料的制备及研究进展

随着便携式电子产品及电动汽车的快速发展,提高锂离子电池能量密度和功率密度的研究日益增多,其中负极材料作为锂离子电池必备部件之一已成为重要的研究方向。商用的石墨负极因理论容量较低限制了其应用,锗具有较高的理论比容量和优异的物理化学性质,成为锂离子电池负极材料的研究热点。本文介绍了不同形貌和组成的锗基纳米负极材料的制备方法以及国内外的研究进展,并对未来的发展方向进行了展望。     

Effects of mineralizing agent on the morphologies and photoluminescence properties of Eu-doped ZnO nanomaterials

Eu-doped ZnO nanomaterials with different morphologies were successfully synthesized with various mineralizing agents by the mild hydrothermal method. The mineralizing agent was found to have strong effect on the crystal structures, morphologies and photoluminescence properties of the samples. Transmission electron microscopy and scanning electron microscopy images showed the Eu-doped ZnO nanorods, nanoneedles and cactus-like microspheres based on nanosheets can be fabricated by choosing NaOH, C₆H₁₂N₄ and (NH₂)₂CO as the mineralizing agents, respectively. The results from X-ray diffraction and X-ray photoelectron spectroscopy indicated europium ions with trivalent valence were successfully doped into the crystal lattice of ZnO matrix. In the PL spectra from the Eu-doped ZnO nanomaterials synthesized with mineralizing agents of NaOH or (NH₂)₂CO, three separated red emissions can be obviously observed, which can be attributed to the 4f-4f intrashell transitions of ⁵D₀ → ⁷F₀, ⁵D₀ → ⁷F₁ and ⁵D₀ → ⁷F₂ of Eu³⁺ ions, respectively. The intensity of red emission was found to be related with the concentration of intrinsic defects, especially O-vacancies, which could assist the energy transfer from the ZnO host to the Eu³⁺ ions.     

一维金属纳米材料的研究进展

介绍了一维金属纳米材料如金、银、铜、铁、锡、钨和钯等的主要种类及其最新的研究进展,系统地阐述一维金属纳米材料的两种制备方法:气相合成法和液相合成法;归纳了一维金属纳米材料的主要性能及其应用:光学性能及其应用、电学性能及其应用、热稳定性能及其应用、磁学性能及其应用、气敏性能及其应用;展望了一维金属纳米材料的发展趋势。     

质子交换膜燃料电池催化剂纳米铂材料研究进展

提高活性、降低贵金属担载量是质子交换膜燃料电池(PEMFC)催化剂的重点研究内容,纳米铂材料是提高阴极氧还原反应(ORR)活性的核心研究方向之一。基于对104篇文献的分析,综述了纳米铂颗粒的粒径、晶面和形貌对催化剂的活性和寿命的影响,以及纳米铂合金的成分和核-壳结构等因素对催化性能的影响。分析现有方法技术的优点和不足,提出催化剂有序化结构和优化ORR反应过程的研究方向。     

Comparison of structural and optical properties of TeO<Subscript>2</Subscript> nanostructures synthesized using various substrate conditions

Several TeO₂ low-dimensional nanostructures were prepared by thermal evaporation using four substrate conditions: (1) a bare substrate, (2) a scratched substrate, (3) a Au-catalyst-assisted substrate, and (4) a multi-walled carbon nanotube (MWCNT)-assisted substrate. Scanning electron microscopy and transmission electron microscopy analysis reveals that the morphologies of the nanostructures synthesized using these methods gradually changed from nanoparticles to ultra-thin nanowires with single tetragonal-type TeO₂. Photoluminescence (PL) spectra reveal that the PL intensities of the TeO₂ nanomaterials obtained using methods (1) and (2) are slightly increased, whereas the intensities of the TeO₂ nanostructures obtained using methods (3) and (4) differ significantly depending on the initial substrate conditions. The emission peak is also blue-shifted from ~440 nm to ~430 nm for the scratched surface condition due to an excitonic transition. The increase in the blue emission for the MWCNT-assisted condition is attributed to the degree and type of excitons and defects in the TeO₂ nanostructures.     

纳米技术的发展及其在模具行业的应用

为了更好地推动纳米材料的应用,介绍了纳米技术及纳米材料的性能、用途,并就纳米技术、纳米材料在模具工业中的应用前景进行了展望。     

纳米镁基储氢材料对AP热分解性能的影响

采用直流电弧等离子体加高压氢化法制备了纳米镁基储氢材料Mg-H和MgEr-H,并对其相组成和放氢性能进行了表征,结果表明添加稀土元素Er可使Mg粉的吸氢更完全,同时使MgH2的放氢温度降低。采用同步热分析方法(TG/DSC)分析了镁基储氢材料对高氯酸铵(AP)热分解性能的影响,结果表明两种镁基储氢材料都能有效促进AP的低温和高温分解过程,尤其是高温分解峰温下降了约80℃,并且使得表观放热量大幅增加,可达纯AP放热量的2倍多,反应过程更为剧烈。添加稀土的镁基储氢材料对AP分解的催化效果更好。     

导电基底表面钴基纳米材料的合成及其对丙酮酸浓度的检测

采用简便无模板的溶剂热法,直接在氧化铟锡导电玻璃(indium tin oxide,ITO)表面上制备高质量的絮状金属钴纳米球,研究了晶种Ru的沉积和前驱体醋酸钴的浓度等,对金属钴纳米球的形貌和大小的影响;利用CV,SEM和EDS分析对钴纳米球进行了形貌的分析和成分表征.用电化学方法对产物进行处理后,得到了六角片状的氢...     

W粉末的形貌结构对板状晶硬质合金的组织与性能的影响

采用W+Co+C(碳黑)为原料制备板状晶硬质合金,研究了不同形貌结构的氧化钨所制备的W粉末形貌结构对板状晶硬质合金组织、性能的影响。结果表明,不同于蓝钨制备的高温中颗粒W粉呈类球状或斜方十二面体结构,黄钨制备的W粉末颗粒呈多面体等轴状,更易于通过球磨获取扁平化程度高的W粉末,制备出板晶化程度高,板状晶的长、径比大,晶粒的取向性好的板状晶硬质合金。     

Production of carbonic nanomaterials in the course of electrodischarge treatment of organic liquids

The processes of electrodischarge destruction of liquid hydrocarbons to produce carbon nanomaterials have been studied. It has been shown that the product yield increases with the growth of the carbon chain length of the initial hydrocarbon. It has been established that, in the course of the treatment, both solid carbon nanomaterials and gas products are formed. The gas products consist of hydrogen and low molecular weight alkanes. It is shown that the hydrocarbon destruction process is accompanied by the change of the carbon atom hybridization, thus influencing the qualitative composition of the carbon nanomaterials.     

新型碳纳米材料用于有机防腐涂层的研究进展

综述了碳纳米材料用于腐蚀防护中的研究进展,重点介绍了几种碳纳米材料,包括富勒烯、碳纳米管、碳纳米纤维、石墨烯、石墨炔以及碳点.碳纳米材料具有优异润滑性能、导电导热性能和屏蔽性能等,在涂层防护领域具有广阔应用前景.具有二维片层结构的碳纳米材料,可在涂层内部构建多重高效屏障,有效提升涂层的屏蔽性能.碳纳米材料的表面存在负电荷,可有效地抑制氯离子和氢氧根离子的渗透过程,降低涂层与金属界面间的阴离子浓度,减缓涂层与金属界面发生腐蚀的几率.碳纳米材料本身具有润滑性能,可实现减摩,提升涂层的耐磨性能.此外,对碳纳米材料涂层的制备、性能及防腐机理等进行了详细阐述,对碳纳米材料在有机防腐涂层中的发展前景进行了展望.     

纳米技术在焊接领域的应用

回顾了纳米材料和纳米技术在焊接领域的应用历程.根据纳米材料和纳米技术的独特功能,探讨了将其应用于焊接材料、焊接结构、难焊材料、焊接保护及其它焊接领域的原理和可能性.对纳米材料和纳米技术在焊接材料的焊丝涂层、焊条药皮、焊剂制造和电极材料中的应用;对接头组织不均匀性、抗磨损、抗疲劳、抗应力腐蚀性能的改善作用分别进行了详细阐述.初步提出了纳米材料和纳米技术在焊接领域中应用值得关注的原材料制备和成本、加入方式、反应机理等问题,展望了纳米材料和纳米技术在焊接领域应用的前景.     

气相氧化法制备氧化锌的结晶形貌

研究了锌蒸气高温气相氧化条件对氧化锌结晶形貌的影响结果.结果表明:气相氧化法制备的氧化锌有无定形、颗粒状、单针状、四针状、多针状等5种典型的结晶形貌;这些结晶形貌与原料锌粉的粒度及表面状态没有直接联系,但都强烈地依赖于锌蒸气氧化时的物理化学环境;在不同的氧分压下,锌蒸气具有不同的氧化行为,由此导致了不同形貌的氧化锌结晶;通过改变制备条件可以有效地调控氧化锌的结晶形貌.     

高速发展的纳米产业

纳米材料市场似乎是无限大的。对纳米技术制品市场作了预测。介绍了几种纳米颗粒的制造方法。概述纳米技术应用的关键领域及其应用实例。     

Effect of irradiation on the properties of nanomaterials

Data are generalized on the results of irradiation of nanostructured materials (hereafter, nanomaterials) based on metals, steels, and some compounds (such as oxides, nitrides, carbides, and intermetallic compounds) by metallic and gaseous ions in accelerators and by neutrons under reactor conditions. The effects of the fluence, energy of ions (neutrons), and irradiation temperature on the phase composition, amorphization, nanostructural parameters, impurity segregation, blistering and swelling, electrical and optical properties, hardness, strength, plasticity, fracture toughness, and other characteristics have been considered. Attention is given to the fact that the consolidated (bulk) nanomaterials and isolated nanoparticles behave differently under irradiation. The results of theoretical studies and simulation (by the moleculardynamics method) of the effect of irradiation on the properties of nanomaterials are analyzed.