Filamentous Carbon Catalytic Deposition of Coal-Tar Pitch Fraction on Corundum

Our work was focused on deposition of volatile hydrocarbons of carbonaceous precursor on corundum wafer, taking advantage of a metallic catalyst incorporated in precursor. Coal tar-pitch, namely a fraction soluble in toluene, served as precursor material for deposition of filamentous material. The toluene-soluble fraction of tar-pitch originally contained metallic particles of iron and nickel. During heat treatment up to 1000°C, metallic particles accompanied the volatile hydrocarbons conducive to forming a filamentous deposit. The deposit obtained demonstrates a semicrystalline material that has an irregular filamentous structure with an average filament diameter of 30 µm. The presence of catalysts after the deposition process was proved in the deposit but catalysts were not found in the residuum.     

Contact and frictional behavior of rough surfaces using molecular dynamics combined with fractal theory

The microcontact behavior of a copper asperity on a diamond plate was carried out using a molecular dynamics (MD) simulation with the parallel algorithms atom decomposition method. The results show that the dynamic frictional force had an oscillated behavior when the flat diamond plane slipped through the copper asperity. The contact load, contact area, dynamic frictional force, and dynamic frictional coefficient increased as the contact interference increased at a constant loading velocity. The dynamic frictional force and dynamic frictional coefficient increased as the sliding velocity increased. Furthermore, the microcontact behavior can be evaluated between a rigid smooth flat plane and a rigid smooth hemisphere to a deformable rough flat plane by combining the deformed behavior of the asperity obtained from MD results and the fractal and statistic parameters.     

纳米晶体硅量子点薄膜的制备及表征

利用激光烧蚀沉积法在n-Si（100）衬底上制备非晶硅（α-Si）薄膜，再经过高温退火技术处理使α-Si晶化成纳米硅晶体（nc—Si）量子点．利用拉曼（naman）L谱仪、X射线衍射仪（XRD）、透射电子显微镜（TEM）以及原子力显微镜（AFM）等测试仪器对nc-Si薄膜进行表征，发现制备的nc-Si量子点排列紧密、尺寸均匀，具有很好的单晶结构，制备的nc-Si薄膜晶化比例很高，并且优先选择在[111]方向晶化．     

Study of the effect of process parameters for n-heptylamine plasma polymerization on final layer properties

Plasma polymerization processes are widely used to chemically functionalize surfaces, which properties can be tuned by different operating variables. In this study, thin amine-containing polymer layers were produced on solid substrates in a custom-made cylindrical plasma polymerization reactor by radio frequency glow discharges of n-heptylamine vapours. Carefully planned experiments were conducted to evaluate the importance of four different process parameters on the chemical composition and thickness of the resulting films. The parameters investigated were: 1) deposition time, 2) power of the glow discharge, 3) distance between the electrodes, and 4) monomer pressure. Possible interactions between these variables were investigated through the use of statistical analyses (i.e., factorial design). This study reveals that n-heptylamine plasma polymer (HApp) layer thickness is influenced by the power of the glow discharge and the deposition time, as assessed by surface plasmon resonance and atomic force microscopy step height measurements. Also, the atomic ratio of nitrogen to carbon atoms on the treated surfaces is mainly influenced by the power of the glow discharge, as revealed by X-ray photoelectron spectroscopy. Quartz crystal microbalance analysis also confirmed that HApp layers are stable when immersed in aqueous solution.     

Growth of β-FeSi2 thin films on β-FeSi2 (110) substrates by molecular beam epitaxy

We have investigated the preparation of β-FeSi₂ substrate and growth condition of β-FeSi₂ thin film on β-FeSi₂ (110) substrate by molecular beam epitaxy. The surface of the substrate was prepared by a wet-etching using HF(50%):HNO₃(60%):H₂O = 1:1:5 solution at 25 °C. It is clear that the optimal etching period to obtain a flat surface was 3 min. The β-FeSi₂ thin film with streak RHEED pattern was obtained at Si/Fe flux ratio of 2.9. Average surface roughness (Ra) of the β-FeSi₂ film was about 0.5 nm in 5 × 5 μm² area.     

On the processing-structure-property relationship of ITO layers deposited on crystalline and amorphous Si

Indium-tin-oxide (ITO) antireflection coatings were deposited on crystalline Si (c-Si), amorphous hydrogenated Si (a-Si:H) and glass substrates at room temperature (RT), 160 °C and 230 °C by magnetron sputtering. The films were characterised using atomic force microscopy, transmission electron microscopy, angle resolved X-ray photoelectron spectroscopy, combined with resistance and transmittance measurements. The conductivity and refractive index as well as the morphology of the ITO films showed a significant dependence on the processing conditions. The films deposited on the two different Si substrates at higher temperatures have rougher surfaces compared to the RT ones due to the development of crystallinity and growth of columnar grains.     

Metallic nickel nanorod arrays embedded into ordered block copolymer templates

We report on metallic Nickel nanorods prepared by utilizing a mask of ordered nanostructured hollow channels in a block copolymer matrix. These polymeric templates were formed by a self organized process in block copolymer supramolecular assemblies. Nickel was filled into with two different techniques, electrodeposition and washing in. We monitor the formation process of these nanorods by means of atomic force microscopy and synchrotron radiation soft X-ray based photoelectron emission microscopy. The oxidation state of the nickelrods is evaluated with X-ray absorption spectroscopy and X-ray photoelectron spectroscopy at the Ni L edges and lateral distributions of the Ni nanorods were detected with micrometer resolved X-ray absorption spectroscopy. The finding is that the Ni rods were metallic despite their preparation under ambient conditions, inside the particles no hints for NiO complexes were found. This indicates that the polymer protects Ni nanoparticles against oxidation.     

Effect of 80 MeV Au ions irradiation on CuInTe2 single crystals grown by CVT technique

Single crystals of CuInTe₂ (CIT) have been grown by the chemical vapor transport (CVT) technique using iodine as the transporting agent. CIT crystals were irradiated with 80 MeV Au⁸⁺ ions at room temperature at different fluences. The surface roughness was measured using an atomic force microscope (AFM). It was found to increase from 9.319 nm in the as-grown sample to 61.169 nm in the sample irradiated with a fluence of 1×10¹³ ions/cm². The intensities of the X-ray diffraction peaks corresponding to the (112) and (004/200) planes of the irradiated sample decrease with respect to the fluences. The full-width at half-maximum (FWHM) of X-ray rocking curves was measured as a function of different ion fluences. The FWHW increases with increase of ions fluences. This is attributed to the irradiation-induced partial amorphization of the top surface of the CIT crystals. The fall in absorption coefficients with photon energy is sharper for as-grown samples than irradiated samples. The band gap value gradually decreases from 1.04 to 0.977 eV upon Au⁸⁺ ions’ irradiation with a fluence of 1×10¹³ ions/cm². Photoluminescence (PL) measurements show a red shift compared to the as-grown CIT single crystals. The Raman modes of A₁ (high) and E and/or B₂ (LO) are observed at 123 and 173 cm⁻¹ in as-grown CIT single crystals, respectively. As the ion fluence is increased, the Raman frequency increases and the curves broaden. The above observed features are related to the large electronic energy transfer of the Au beam to the CIT crystals.     

Surface modification of indium tin oxide anodes by self-assembly monolayers: Effects on interfacial morphology and charge injection in organic light-emitting diodes

Three silane derivatives including dodecyltrichlorosilane (DDTS), phenyltriethoxysilane (PTES) and 3-aminopropyl-methyl-diethoxysilane (APMDS) were used to modify the indium tin oxide (ITO) surfaces. The effects of various terminal groups of the self-assembled monolayers (SAMs) on the growth behavior and interfacial morphologies of N,N′-di(naphthalene-1-yl)-N,N′-diphenylbenzidine (NPB) film deposited on the SAM-modified ITO were studied, as well as their effects on the performance of organic light-emitting diodes (OLED) devices. The results show that the growth behavior of NPB film over-deposited on the SAM-modified ITO is mainly determined by the wettability of the surface. The covering ability and thermal stability of NPB film on the SAM-modified ITO decrease in the order: bare ITO > ITO/PTES > ITO/APMDS > ITO/DDTS. However, the covering characteristic of NPB films on these substrates did not show direct relation to the transport of carriers across the anode/NPB interface as evaluated from the cyclic voltammogram and OLED performance. The turn-on voltages for these SMA-modified OLED devices increase in the order: ITO/PTES < ITO/DDTS ≤ bare ITO < ITO/APMDS. The enhancing effect of PTES on the hole injection is ascribed to the similar structure of PTES to NPB. On the contrary, the inhibition effect of APMDS is caused from the interaction of the lone-pair electrons of amine group to the transport carriers. Since these devices are known to be hole dominant, the luminance efficiency increase in a similar order as that for the turn-on voltage: ITO/PTES < ITO/DDTS ≤ bare ITO < ITO/APMDS.     

氩等离子体预处理对纳米结构银非织造布抗菌性能的影响

采用磁控溅射技术,在丙纶非织造布(PP)基材表面沉积厚度为0.5～3 nm的纳米结构银薄膜,重点研究了PP基材经氩等离子体预处理前后对纳米结构银薄膜抗菌性能的影响.采用振荡烧瓶法测试样品的抗菌性能,利用原子力显微镜(AFM)观察氩等离子处理前后PP基材表面的形态变化,同时应用EDX对纳米结构银薄膜进行元素分布及定量分析.实验结果表明:在纳米结构银薄膜厚度相同的条件下,经氩等离子预处理的丙纶非织造布具有更好的抗菌性能;AFM分析表明,经氩等离子处理后的纤维表面有明显的刻蚀痕迹,纤维表面凹凸不平,形成很多微小的空隙,溅射出的银粒子不易团聚,活性增加,抗菌性能因此提高;而EDX结果分析表明,抗菌性能提高是由于经氩等离子处理后,银离子溶出总量增加的缘故.