纳米孔径核孔膜的制备研究

高能硫、氪、氙离子轰击聚酯(PET)和聚碳酸酯(PC)膜后，对样品进行陈化和紫外线照射敏化．用电导法着重研究蚀刻条件对样品的归一亿径迹蚀刻速率(灵敏度)的影响，结果表明优化条件下灵敏度较通用条件下提高约2倍，PET的灵敏度可达1000，PC的灵敏度可达2000，可以用于制备纳米孔径核孔膜．核孔膜中填充的铜纳米线的电镜照片显示出纳米线最小直径为20nm．用电导法计算纳米孔的孔径，该值与纳米线直径的电镜测量值在孔径大于30nm时符合良好．     

纳米孔径核孔模的制备研究

高能硫、氪、氙离子轰击聚酯（PET）和聚碳酸酯（PC）膜后,对样品进行陈化和紫外线照射敏化。用电导法着重研究蚀刻条件对样品的归一化径迹蚀刻速率（灵敏度）的影响,结果表明优化条件下灵敏度较通用条件下提高约2倍,PET的灵敏度可达1000,PC的灵敏度可达2000,可以用于制备纳米孔径核孔膜。核孔膜中填充的铜纳米线的电镜照片显示出纳米线最小直径为20nm。用电导法计算纳米孔的孔径,该值与纳米线直径的电镜测量值在孔径大于30nm时符合良好。     

X光纳米充刻掩模的离子束制备法

重离子柬轰击聚碳酸酯后．对样品进行陈化和紫外线照射数化,在优化条件下蚀刻后得到纳米孔径核孔膜。利用电化学沉积技术在核孔膜中制备了最小孔径为30纳米的铜纳米线。获得的钥纳米线／聚碳酸酯可以作为x光纳米光刻的腌膜。     

核孔膜的非常规蚀刻法

不对称蚀刻法的分桥表明,在灵敏度不变时可以得到小孔径核孔膜。实验显示,由于孔径不均匀现象的制约,核孔膜的孔径可减小到1／2。温度梯度蚀刻法的分桥表明,导通时间的减小与膜两面的温度差成正比,在实际条件下孔径减小到1／5。模拟计算表明,采用该方法可得到控状孔核孔膜,但蚀刻过程很难控制。     

~(32)S离子辐照PET薄膜制备亚微米孔径核孔膜研究

使用中国原子能科学研究院HI-13串列加速器产生的32S离子轰击BOPET薄膜,薄膜在空气中陈化3个月后在专用装置中使用Na OH溶液蚀刻制备核孔膜,研究Na OH溶液浓度、蚀刻温度对微孔孔形的影响。在不同温度和蚀刻液浓度条件下,蚀刻出微孔孔径为0.2至0.93μm的亚微米核孔膜,计算其微孔锥角,得出微孔锥角随着蚀刻温度、蚀刻液浓度和微孔孔径的变化趋势。研究表明,采用低浓度、高温度的Na OH溶液蚀刻有利于减小微孔锥角,有利于制备较小孔径的核孔膜。如选用0.5mol/L的Na OH溶液浓度,在蚀刻温度为90℃的条件下蚀刻,此时蚀刻时间小于2 h,既可以得到高质量微孔膜也有利于提高生产效率。     

云母模板中Cu纳米线的制备及其光学性质研究

利用快重离子辐照的单晶白云母片产生潜径迹,蚀刻得到直径在30—180 nm纳米孔道. 孔道形状依赖于蚀刻时间,蚀刻时间短得到圆柱形孔道,蚀刻时间长得到菱柱形孔道. 从而在云母模板孔道中电化学沉积得到不同直径和形状的Cu纳米线. 通过紫外可见光谱分析,发现铜纳米线的尺寸和形状影响其光学性质. 直径小于60 nm的近似为圆柱状Cu纳米线有一个明显的表面等离子体共振峰和一个微弱的次峰. 随着直径增加,菱柱状的Cu纳米线主峰有明显的红移,次峰逐渐增强. 同时利用扫描电子显微镜、X射线衍射对Cu纳米线的形貌和晶体结构特征进行了表征. 关键词： Cu纳米线 电化学沉积 光学性质 云母模板     

NiFe2O4纳米线阵列的制备与磁性

在氧化铝模板的纳米孔洞中, 用电化学的方法沉积铁镍合金纳米线,经过550℃30h氧化处理, 成功制备出 NiFe2O4纳米线阵列. 分别用扫描电子显微镜 (SEM) 、透射电子显微镜 (TEM) 、x射线衍射仪 (XRD) 和振动样品磁场计 (VSM) 对样品的形貌、晶体结构和磁学性质进行了表征测试. SEM和TEM观察结果显示氧化铝模板的孔洞分布均匀,孔心距约为110nm; 纳米线的直径约为70nm. XRD显示纳米线阵列的物相结构为NiFe2O4; VSM测试结果表明,NiFe2O4纳米线阵列膜的易磁化方向垂直于膜面. 当垂直磁化时磁滞回线的矩形比约为0.5,矫顽力为41×103A/m,比氧化处理前的铁镍合金纳米线阵列都有显著提高.     

高取向As掺杂ZnO纳米线阵列的制备与表征

在不采用任何金属催化剂的条件下,运用化学气相沉积法,在Si(100)衬底上制备出高取向的As掺杂ZnO纳米线阵列.样品的X射线衍射(XRD)谱显示获得了单一取向的衍射峰,表明样品具有较好的结晶质量.场发射扫描电镜(FE-SEM)观察表明,As掺杂ZnO纳米线阵列具有均一的直径和长度,其顶部和根部直径分别为70 nm和1...     

NiFe2O4纳米线阵列的制备与磁性

在氧化铝模板的纳米孔洞中, 用电化学的方法沉积铁镍合金纳米线，经过550℃30h氧化处理 , 成功制备出 NiFe2O4纳米线阵列. 分别用扫描电子显微镜 (SEM) 、透射电 子显微镜 (TEM) 、x射线衍射仪 (XRD) 和振动样品磁场计 (VSM) 对样品的形貌、晶体结构 和磁学性质进行了表征测试. SEM和TEM观察结果显示氧化铝模板的孔洞分布均匀，孔心距约 为110nm; 纳米线的直径约为70nm. XRD显示纳米线阵列的物相结构为NiFe2O4; VSM测试结果表明，NiFe2O4纳米线阵列膜的易磁化方向垂直于膜面. 当垂直 磁化时磁滞回线的矩形比约为05，矫顽力为41×103A/m，比氧化处理前的铁镍合金 纳米线阵列都有显著提高. 关键词： 纳米线 Ni Fe2O4 矫顽力     

银纳米线的侧向生长及其抑制研究

采用多元醇法,在不同温度,不同PVP滴加速度和加入量的条件下合成了银纳米线。利用XRD, UV-Vis, SEM和TEM对银纳米线及其侧向生长过程进行了观察和分析。UV-Vis表明银纳米线在纵向生长的同时发生了侧向生长。而且表示银纳米线侧向生长的紫外吸收光谱峰在银纳米线合成后期发生了明显的红移,由384 nm红移至约388 nm处,表明银纳米线合成后期直径迅速增长,银纳米线发生了快速的侧向生长。SEM研究表明银纳米线直径在反应前期(15～23 min)只增加了20 nm,而在反应后期(23～30 min)银纳米线直径增加了近150 nm,SEM观察结果与UV-Vis分析结论一致。同时还发现银纳米线直径不仅与晶种大小有关而且与银线外覆盖的银层厚度有关,银源以吸附在银线侧面的小银颗粒为附着点沿其侧面多点沉积导致了银纳米线的侧向生长;降低反应液温度(165 ℃降至155 ℃),降低PVP滴加速度(67 mL·h-1减小到49 mL·h-1)以及减少银纳米线合成后期PVP加入量可抑制银纳米线的侧向生长,显著提高银纳米线长径比,银纳米线直径由200 nm减小至100 nm左右,长度仍保持在100 μm以上。     

Crystallographically-oriented single-crystalline copper nanowire arrays electrochemically grown into nanoporous anodic alumina templates

Highly crystallographically-oriented single-crystalline copper nanowire arrays were electrochemically deposited into nanoporous commercial alumina templates. A gold/copper backward contact was needed in the template, while the nanowires were grown from a 0.5 M CuSO₄·5H₂O solution adjusted to pH=1. The kinetics of the growing process is studied by means of current vs. time curves. The pore filling is between 80 to 90%. The structure and morphology of the wires are studied by XRD, SEM and TEM. The wires have an average diameter of 150 nm corresponding to the pore diameter of the template, with the cubic face-centered copper structure. This structure is highly oriented along the [100] direction parallel to the wire axis. The preferential growing along this direction was not previously found in the literature, which may have interesting applications when such direction is required. PACS 81.05.Bx; 82.45.Qr; 81.07.-b     

Template synthesis of single-crystal Cu nanowire arrays by electrodeposition

Cu nanowire arrays have been synthesized using potentiostatic electrodeposition within the confined nanochannels of a porous anodic alumina membrane. The Cu nanowire arrays and the individual nanowires have been characterized using SEM, TEM, SAED, HREM and XRD. Investigation results reveal that the Cu nanowire arrays having high wire packing densities are highly ordered over large areas. The individual Cu nanowires (diameter ∼60 nm) were single-crystal and found to be dense and continuous with uniform diameters throughout their entire length. An optimum ECD condition (at lower overpotentials) for the synthesis of single-crystal Cu nanowires was also discussed. Received: 19 April 2001 / Accepted: 28 April 2001 / Published online: 20 June 2001     

Registration temperature effect in polymers: Physico-chemical aspects

Registration temperature effect in two different polymers - poly(ethylene terephthalate) (PET) and polypropylene (PP) films - is investigated. Temperature effects on track formation are considered in terms of molecular mobility and relaxation transitions. The track eth rate is measured as a function of irradiation temperature in the range of 77 to 373 K. The obtained results are compared with the radical yields, radiothermoluminescence curves and thermally stimulated currents measured with the aim of detecting changes in the mobility of macromolecules and radiolysis intermediates. It is found that the change of the track etch rate with changing registration temperature correlates with γ- and glass transitions in PP and with β-and glass transitions in PET.     

Specific heat of superconducting Zn nanowires

We present heat capacity measurements on crystalline Zn nanowires with diameters of 230 and 23 nm, bracketing the superconducting coherence length of 155 nm. Transport measurements on superconducting nanowires have found a crossover from three-dimensional to one-dimensional behavior as the wire diameter was reduced below the coherence length. In contrast, the normalized heat capacity peak of the 23 nm Zn nanowires is found to be nearly identical to that of 230 nm wires and bulk Zn, indicating their thermodynamic properties remain three dimensional.     

Study of the effect of varying core diameter,shell thickness and strain velocity on the tensile properties of single crystals of Cu–Ag core–shell nanowire using molecular dynamics simulations

Core–shell type nanostructures show exceptional properties due to their unique structure having a central solid core of one type and an outer thin shell of another type which draw immense attention among researchers. In this study, molecular dynamics simulations are carried out on single crystals of copper–silver core–shell nanowires having wire diameter ranging from 9 to 30 nm with varying core diameter, shell thickness, and strain velocity. The tensile properties like yield strength, ultimate tensile strength, and Young’s modulus are studied and correlated by varying one parameter at a time and keeping the other two parameters constant. The results obtained for a fixed wire size and different strain velocities were extrapolated to calculate the tensile properties like yield strength and Young’s modulus at standard strain rate of 1 mm/min. The results show ultra-high tensile properties of copper–silver core–shell nanowires, several times than that of bulk copper and silver. These copper–silver core–shell nanowires can be used as a reinforcing agent in bulk metal matrix for developing ultra-high strength nanocomposites.     

On the response of LR-115 plastic track detector to 10 20 Ne-ion

The track etch rates of ₁₀ ²⁰ Ne-ion in cellulose nitrate (LR-115) have been measured for different temperatures and the activation energy is determined. The experimental results show that both the track etch rate and the normalized track etch rate depend on the energy loss as well as on etching temperature. The maximum etched track length of ₁₀ ²⁰ Ne-ion agrees with the theoretically computed range. The experimental results show that there is no sharp threshold, at least in CN(LR-115).     

超声波酸性体系下MCM-41的合成及表征

以十六烷基三甲基溴化铵(CTAB)为模板剂,正硅酸乙酯(TEOS)为硅源,以超声波为辅助手段于酸性介质中制备出了MCM-41介孔分子筛,采用XRD、TEM、FTIR等手段对样品进行了分析表征.结果表明,所合成样品具备MCM-41所特有的六方排列的一维孔道结构和较高的有序度,所合成的MCM-41平均粒径为11nm,孔径约为2.7nm.     

SHI induced nano track polymer filters and characterization

Swift heavy ion irradiation produces damage in polymers in the form of latent tracks. Latent tracks can be enlarged by etching it in a suitable etchant and thus nuclear track etch membrane can be formed for gas permeation / purification in particular for hydrogen where the molecular size is very small. By applying suitable and controlled etching conditions well defined tracks can be formed for specific applications of the membranes. After etching gas permeation method is used for characterizing the tracks. In the present work polycarbonate (PC) of various thickness were irradiated with energetic ion beam at Inter University Accelerator Centre (IUAC), New Delhi. Nuclear tracks were modified by etching the PC in 6N NaOH at 60 (±1) °C from both sides for different times to produce track etch membranes. At critical etch time the etched pits from both the sides meet a rapid increase in gas permeation was observed. Permeability of hydrogen and carbon dioxide has been measured in samples etched for different times. The latent tracks produced by SHI irradiation in the track etch membranes show enhancement of free volume of the polymer. Nano filters are separation devices for the mixture of gases, different ions in the solution and isotopes and isobars separations. The polymer thin films with controlled porosity finding it self as best choice. However, the permeability and selectivity of these polymer based membrane filters are very important at the nano scale separation. The Swift Heavy Ion (SHI) induced nuclear track etched polymeric films with controlled etching have been attempted and characterized as nano scale filters.      

Cu/C核/壳纳米结构的气相合成、形成机理及其光学性能研究

采用乙酰丙酮铜为原料, 通过化学气相沉积大批量制备出Cu/C核/壳纳米颗粒和纳米线. 研究结果表明, 通过控制沉积温度可对Cu/C核/壳纳米材料的形貌和结构进行很好的控制. 比如, 沉积温度为400 ℃时可获得直径约200 nm的Cu/C核/壳纳米线, 沉积温度为450 ℃ 时可获得直径约200 nm的Cu/C核/壳纳米颗粒和纳米棒的混合产物, 沉积温度为600 ℃时可获得直径约22 nm的Cu/C核/壳纳米颗粒. 获得的Cu/C核/壳纳米结构是由一个新颖的凝聚机理形成的, 而这种机理不同于著名的溶解-析出机理. 紫外-可见光谱和荧光光谱分析结果表明: Cu/C核/壳纳米线和纳米颗粒均在225 nm处出现Cu的吸收峰, 同时在620 和616 nm处分别出现了纳米线和纳米颗粒的表面等离子共振吸收峰. Cu/C核/壳纳米线在312 和348 nm处、 Cu/C核/壳纳米颗粒在304 和345 nm处出现荧光发射谱峰. 关键词： Cu/C核/壳结构 纳米线 纳米颗粒 光学性能     

Silver nanowires electrodeposited into nanoporous templates: Study of the influence of sizes on crystallinity and structural properties

In this work, results on the study of the influence of silver nanowire dimensions on the crystallinity and structural properties are presented. Silver nanowire arrays with high aspect ratios were prepared in the hollow structures of nanoporous templates using potentiostatic electrodeposition. Two types of material were employed as a template: commercial porous anodic aluminum oxide (with a mean pore diameter of 180 nm) and track-etched polycarbonate membranes (with a mean pore diameter of 15, 30 and 80 nm). Characterization of the silver nanowires has been done by EDS, XRD, TEM and electron diffraction. The degree of preferred crystallographic orientation (along the (1 1 1), (2 0 0) or (2 2 0) crystallographic planes) and the crystallite size of the silver nanowires as a function of template pore diameter are given and discussed.