Growth of ordered silver nanoparticles in silica film mesostructured with a triblock copolymer PEO-PPO-PEO

Elaboration of mesostructured silica films with a triblock copolymer polyethylene oxide-polypropylene oxide-polyethylene oxide, (PEO-PPO-PEO) and controlled growth of silver nanoparticles in the mesostructure are described. The films are characterized using UV-visible optical absorption spectroscopy, TEM, AFM, SEM, X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). Organized arrays of spherical silver nanoparticles with diameter between 5 and 8 nm have been obtained by NaBH₄ reduction. The size and the repartition of silver nanoparticles are controlled by the film mesostructure. The localization of silver nanoparticles exclusively in the upper-side part of the silica-block copolymer film is evidenced by RBS experiment. On the other hand, by using a thermal method, 40 nm long silver sticks can be obtained, by diffusion and coalescence of spherical particles in the silica-block copolymer layer. In this case, migration of silver particles toward the glass substrate-film interface is shown by the RBS experiment.     

Comparative investigation on copper oxides by depth profiling using XPS, RBS and GDOES

Depth profiling has been performed by using X-ray photoelectron spectrometry (XPS) in combination with Ar-ion sputtering, Rutherford backscattering spectrometry (RBS) and glow discharge optical emission spectrometry (GDOES). The data obtained by XPS have been subjected to factor analysis in order to determine the compositional layering of the copper oxides. This leads to two or three relevant components within the oxide layers consisting of Cu₂O or CuO dependent on the sample preparation. GDOES measurements show sputtering profiles which are seriously influenced by a varying sputter rate. To ensure the results obtained so far, RBS measurements of the oxide layers have been carried out in order to discover artefacts of the other methods used and to demonstrate the excellent suitability of RBS for quantitative analysis of these layers. Chemical analysis consisting of (1) carrier-gas fusion analysis (CGFA) and (2) selective dissolution of Cu₂O/CuO allows the determination of the total amount of oxygen and copper, respectively, and can serve as a cornerstone of quantitative analysis.     

Shape-controlled solvothermal synthesis of bismuth subcarbonate nanomaterials

Much effort has been devoted to the synthesis of novel nanostructured materials because of their unique properties and potential applications. Bismuth subcarbonate ((BiO)₂CO₃) is one of commonly used antibacterial agents against Helicobacter pylori (H. pylori). Different (BiO)₂CO₃ nanostructures such as cube-like nanoparticles, nanobars and nanoplates, were fabricated from bismuth nitrate via a simple solvothermal method. The nanostructures were characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). It was found that the solvents and precursors have an influence on the morphologies of (BiO)₂CO₃ nanostructures. The possible formation mechanism of different (BiO)₂CO₃ nanostructures fabricated under different conditions was also discussed.     

Deposition and Characterization of Luminescent Eu(tta)3phen‐Doped Parylene‐Based Thin‐Film Materials

Herein, novel host–guest films produced by coarse vacuum cosublimation of the parylene C dimer and Eu(tta)₃phen are prepared and studied. Eu(tta)₃phen sublimation at different temperatures allows films with different concentrations of the Eu complex to be obtained. The films are characterized by Rutherford backscattering spectrometry (RBS), FTIR spectroscopy, X‐ray diffraction (XRD), atomic force microscopy (AFM), and UV/Vis absorption and emission spectroscopy. RBS, FTIR, and XRD reveal the incorporation of Eu(tta)₃phen into the parylene matrix. AFM evidences the very flat film surface, which is particularly advantageous for optical applications. UV/Vis absorption and emission analyses confirm that the optical properties of Eu(tta)₃phen are preserved in the deposited films. Fluorescence measurements evidence the occurrence of an energy‐transfer process between parylene and Eu(tta)₃phen, and this results in an increase in the light emitted by the Eu complex that is as much as five times higher than that emitted by Eu(tta)₃phen alone.     

Analysis of Co and Cr dopants in epitaxial films of β-FeSi2 by ERDA, RBS, EDX and AES

Thin films of β-FeSi₂ doped with Co or Cr were grown on Si substrates by molecular beam epitaxy. The matrix components Fe and Si and the dopant were co-evaporated from three separately controlled sources. The dopant concentration was measured concurrently by ERDA, RBS, EDX and AES. Ion scattering spectrometry using heavy-ion beams of high energy (ERDA with 250 MeV ¹²⁹Xe, RBS with 15 MeV ¹⁴ N) proved to be most powerful in providing a high mass resolution (1 amu) and a low detection limit for Co and Cr (about 0.2 at %). Although the sensitivity of standard RBS (with 1.4 MeV ⁴He), EDX and AES is limited to a level of about 1 at% these methods allow to assess essential trends caused by variation of the deposition parameters.     

一维多孔Fe-B合金纳米结构的制备及其磁性质

在十六烷基三甲基溴化铵(CTAB)的水溶液中,用NaBH₄还原FeCl₃,在反应过程中施加外部磁场,制得了一维多孔Fe-B合金纳米结构。研究表明,外部磁场对一维纳米结构的形成有重要影响,当不加外部磁场时得到的是离散的球形纳米粒子;外部磁场还影响Fe-B纳米粒子的晶体结构：外部磁场存在下得到的是无定形Fe-B合金,而不加外部磁场时则得到多晶Fe-B合金。CTAB对多孔的形成起到关键的作用,当不加CTAB时得到了实心球状纳米粒子。初步讨论了这种一维孔状Fe-B合金纳米结构的形成机理。用XRD、ICP-AES、TEM对样品进行了表征,测定了它们的磁性质。结果表明,在施加不同磁场强度条件下制得的样品具有不同的饱和磁化强度和矫顽力。     

Solid–liquid interface analysis with in-situ Rutherford backscattering and electrochemical impedance spectroscopy

A novel Rutherford backscattering spectrometry (RBS) method is presented to investigate the interface between a solid surface and a surrounding liquid. The introduced measurement system allows to observe and quantify adsorption at the solid–liquid interface and the formation of the electrochemical double layer (EDL). BaCl₂ as a bicomponent electrolyte and a Si₃N₄ membrane surface are chosen as a model system to prove the capabilities of the setup. The results of these RBS measurements are combined with electrochemical impedance spectroscopy (EIS) to validate the findings for the solid–liquid interface under study. Complementary results and discrepancies regarding the formation of the EDL are discussed.     

Electrochemical synthesis of a novel platinum nanostructure on a glassy carbon electrode, and its application to the electrooxidation of methanol

We show that the addition of white dextrin during the electrochemical deposition of platinum nanostructures (nano-Pt) on a glassy carbon electrode (GCE) results in an electrochemically active surface that is much larger than that of platinum microparticles prepared by the same procedure but in the absence of dextrin. The nano-Pt deposits are characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy, and electrochemical methods. The SEM images reveal deposits composed of mainly nanoparticles and short nanorods. The GCE was applied as a novel and cost-effective catalyst for methanol oxidation. The use of nano-Pt improves the electrocatalytic activity and the stability of the electrodes.

Additive assisted hydrothermal synthesis,characterization and optical properties of one dimensional DyPO4:Ce3+ nanostructures

One dimensional nanostructures of cerium doped dysprosium phosphate (DyPO₄:Ce³⁺) were synthesized via hydrothermal route in the presence of different surfactants [sodium dodecyl sulfate (SDS), dodecyl sulfosuccinate (DSS), polyvinyl pyrollidone (PVP)] and solvent [ethylene glycol and water]. The prepared nanostructures were characterized by Powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), UV-VIS-NIR absorption spectrophotometer and photoluminescence (PL) studies. The PXRD and FTIR results indicate purity, good crystallinity and effective doping of Ce³⁺ in nanostructures. SEM and TEM micrographs display nanorods, nanowires and nanobundles like morphology of DyPO₄:Ce³⁺. Energy-dispersive X-ray spectra (EDS) of DyPO₄:Ce³⁺nanostructures confirm the presence of dopant. UV-VIS-NIR absorption spectra of prepared compounds are used to calculate band gap and explore their optical properties. Luminescent properties of DyPO₄:Ce³⁺ was studied by using PL emission spectra. The effect of additives and solvents on the uniformity, morphology and optical properties of the nanostructures were studied in detail.     

Sonochemical and solvothermal synthesis of methanol {2-[(2-hydroxy-1,1-dimethyl-ethylimino)-methyl]phenolato}-dioxidomolybdenum(VI) complex and its decomposition to MoO<Subscript>3</Subscript> nanoparticles

As a new precursor to prepare nano molybdenum trioxide, methanol {2-[(2-hydroxy-1,1-dimethylethylimino)-methyl]phenolato}dioxidomolybdenum(VI) complex (1) with the Schiff base ligand (H₂L) is synthesized by two different methods: solvothermal and sonochemical. Nanoparticles of 1 are obtained by one-pot solvothermal treatment of methanolic solutions of the ligand and di-oxomolybdenyl acetylacetonate at 150°C for 24 h and for improving the quality of nanostructures by sonochemical method with two types of solvents, different concentrations of initial reagents and also different sonication times. The thermal stability of nanosized compound 1 is studied by thermal gravimetric (TG) analysis and differential scanning calorimetry (DSC). Nanoparticles of orthorhombic α-MoO₃ are obtained by calcination of nanostructures of compound 1 at 700°C. All compounds and the obtained molybdenum trioxide nanostructures are characterized by elemental analysis, FT-IR, UV-Vis spectroscopy, X-ray powder diffraction (XRD), and scanning electron microscopy (SEM).     

Medium energy,heavy and inert ion irradiation of metallic thin films: studies of surface nano‐structuring and metal burrowing

In context to the ion induced surface nanostructuring of metals and their burrowing in the substrates, we report the influence of Xe and Kr ion‐irradiation on Pt:Si and Ag:Si thin films of ~5‐nm thickness. For the irradiation of thin films, several ion energies (275 and 350 keV of Kr; 450 and 700 keV of Xe) were chosen to maintain a constant ratio of the nuclear energy loss to the electronic energy loss (S_n/S_e) in Pt and Ag films (five in present studies). The ion‐fluence was varied from 1.0 × 10¹⁵ to 1.0 × 10¹⁷ ions/cm². The irradiated films were characterized using Rutherford backscattering spectroscopy (RBS), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The AFM and SEM images show ion beam induced systematic surface nano‐structuring of thin films. The surface nano‐structures evolve with the ion fluence. The RBS spectra show fluence dependent burrowing of Pt and Ag in Si upon the irradiation of both ion beams. At highest fluence, the depth of metal burrowing in Si for all irradiation conditions remains almost constant confirming the synergistic effect of energy losses by the ion beams. The RBS analysis also shows quite large sputtering of thin films bombarded with ion beams. The sputtering yield varied from 54% to 62% by irradiating the thin films with Xe and Kr ions of chosen energies at highest ion fluence. In the paper, we present the experimental results and discuss the ion induced surface nano‐structuring of Pt and Ag and their burrowing in Si. Copyright © 2016 John Wiley & Sons, Ltd.     

不同形貌的Cu_2O:可控合成及光学性质(英文)

Cuprous oxide(Cu₂O) hexapodal branch structure with high uniformity was prepared by a solution phase route using sodium dodecyl sulfate as a capping agent. The shapes of Cu₂O crystal(flower-like structure, nanocube and nanoplate) were tuned by varying species and concentrations of surfactants to control the growth rate on different crystal planes of Cu₂O. Cu₂O nanostructures were characterized by UV-Vis spectroscopy, XRD, TEM and SEM. XRD result shows that the obtained Cu₂O belongs to cubic phase. TEM and SEM results demonstrate that specie and concentration of surfactants play a key role in the formation of various morphologies of Cu₂O. The formation mechanism is discussed. Moreover, the optical properties of the obtained Cu₂O are shape-dependent.     

Preparation of Cd(OH)2 nanostructures in water using a simple refluxing method and their photocatalytic activity

Nanostructures of Cd(OH)₂ were prepared using a simple template-free method in water by 4?h refluxing at about 95?°C without using any organic compound. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform-infrared and UV?Cvis diffuse reflectance spectroscopy techniques were applied for characterization of the nanostructures. The XRD pattern demonstrates that the nanostructures are crystallized in hexagonal phase. The SEM image shows that the nanostructures are nearly in plate form. The DRS of the nanostructures shows absorption maxima at about 315?nm. Photocatalytic activity of the nanostructures was investigated by degradation of methylene blue (MB) under UV irradiation. Moreover, the effects of refluxing time and calcination temperature on photocatalytic activity were studied.     

Solvothermal Synthesis and Characterization of PbSe Nanostructures with the Aid of Schiff-base Ligand

In this work, Pb(II)N,N-bis(salicylidene)-ethylenediamine; [Pb(salen)]; was applied as lead precursor to synthesis PbSe nanostructures. Besides [Pb(salen)], SeCl₄ and reducing agents like N₂H₄·H₂O have been employed for the production of PbSe nanostructures via a solvothermal route at 180 °C for 3 h in propylene glycol. The effect of preparation factors such as temperature, reaction time, and surfactant on the morphology of PbSe nanostructures was investigated. The experimental results indicated that PbSe synthesized at 150 and 210 °C was composed of agglomerated particles. On the other hand, the use of KBH₄ as reducing agent led to produce PbSe with higher particle size and agglomeration. The as-prepared PbSe nanostructures were characterized by XRD, SEM, TEM, EDS, and FT-IR.     

Co-templating synthesis of highly dispersed 1D ZnO nanostructures in amorphous SiO2 under hydrothermal condition

One-dimensional (1D) ZnO nanostructures were grown in amorphous SiO₂ matrix by a co-templating method under hydrothermal condition. Using ethylenediamine (EDA) groups grafted mesoporous silica MCM-41 as a co-template, the growth of 1D ZnO nanostructures was oriented by soft EDA groups and confined inside the hard mesochannels of MCM-41. The microstructure and morphology of the 1D-ZnO-nanostructures/SiO₂ composite were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS). All these results indicate that the 1D ZnO nanostructures were synthesized and highly dispersed in the amorphous SiO₂ matrix. Blue-shifted exciton absorption was observed from the co-templating synthesized sample.     

Ag作催化剂制备的GaN的形貌及其性能

用化学气相沉积法(CVD)在Si(100)衬底上以Ag纳米颗粒为催化剂制备了微纳米结构的GaN,原料是熔融态的金属Ga和气态的NH3。采用X射线衍射仪(XRD)、透射电镜(TEM)、X-ray能谱仪(EDS)、场发射扫描电子显微镜(SEM)、光致发光能谱(PL)和霍尔效应测试对样品进行了结构、成分、形貌和发光、电学性能分析。结果表明:生成的自组装GaN为六方纤锌矿的类似小梯子的微纳米单晶结构,且在不同的温度下,GaN的发光性能和电学性能也有所不同,相对于强的紫外发光峰,其它杂质发光峰很微弱,且均呈p型导电。对本实验所得到的GaN微纳米结构的可能形成机理进行了探讨。     

Atomic layer deposition of TiO2 nanotubes and its improved electrostatic capacitance

Titanium dioxide (TiO₂) nanotubes are fabricated into anodic aluminum oxide (AAO) membrane via atomic layer deposition (ALD). For the ALD of TiO₂, gaseous precursors, titanium (IV) isopropoxide and water are sequentially applied and chemically reacted with each other. A thickness of nanotubes is precisely controlled by the applied cycle numbers of ALD and the morphology of nanostructures is investigated by SEM and TEM. The amorphous property of TiO₂ nanostructures is revealed by XRD and the composition of nanotubes is measured by TEM–EDX. The impurity contents and binding structure of the nanostructures are analyzed by XPS. The electrostatic capacitance of TiO₂ nanotubes into AAO is 480 μF/cm² and it is about 3 times higher compared with AAO membrane (172 μF/cm²).     

Impact of high N2 flow ratio on the chemical and morphological characteristics of sputtered N‐DLC films

Because of their outstanding characteristics, diamond‐like carbon (DLC) thin films have been recognized as interesting materials for a variety of applications. For this reason, the effects of the incorporation of different elements on their fundamental properties have been the focus of many studies. In this work, nitrogen‐incorporated DLC films were deposited on Si (100) substrates by DC magnetron sputtering of a graphite target under a variable N₂ gas flow rate in CH₄ + N₂ + Ar gas mixtures. The influence of high N₂ flow ratios (20, 40 and 60%) on the chemical, structural and morphological properties of N‐DLC films was investigated. Different techniques including field emission gun‐equipped scanning electron microscope (FEG‐SEM), energy‐dispersive X‐ray spectroscopy (EDS), atomic force microscopy (AFM), profilometry, Rutherford backscattering spectrometry (RBS) and Raman spectroscopy (325‐nm and 514‐nm excitation) were used to examine the properties of the N‐DLC films. Thus, the incorporation of nitrogen was correlated with the morphology, roughness, thickness, structure and chemical bonding of the films. Overall, the results obtained indicate that the fundamental properties of N‐DLC films are not only related to the nitrogen content in the film but also to the type of chemical bonds formed. Copyright © 2016 John Wiley & Sons, Ltd.     

XPS for non-destructive depth profiling and 3D imaging of surface nanostructures

Depth profiling of nanostructures is of high importance both technologically and fundamentally. Therefore, many different methods have been developed for determination of the depth distribution of atoms, for example ion beam (e.g. O₂⁺, Ar⁺) sputtering, low-damage C₆₀ cluster ion sputtering for depth profiling of organic materials, water droplet cluster ion beam depth profiling, ion-probing techniques (Rutherford backscattering spectroscopy (RBS), secondary-ion mass spectroscopy (SIMS) and glow-discharge optical emission spectroscopy (GDOES)), X-ray microanalysis using the electron probe variation technique combined with Monte Carlo calculations, angle-resolved XPS (ARXPS), and X-ray photoelectron spectroscopy (XPS) peak-shape analysis. Each of the depth profiling techniques has its own advantages and disadvantages. However, in many cases, non-destructive techniques are preferred; these include ARXPS and XPS peak-shape analysis. The former together with parallel factor analysis is suitable for giving an overall understanding of chemistry and morphology with depth. It works very well for flat surfaces but it fails for rough or nanostructured surfaces because of the shadowing effect. In the latter method shadowing effects can be avoided because only a single spectrum is used in the analysis and this may be taken at near normal emission angle. It is a rather robust means of determining atom depth distributions on the nanoscale both for large-area XPS analysis and for imaging. We critically discuss some of the techniques mentioned above and show that both ARXPS imaging and, particularly, XPS peak-shape analysis for 3D imaging of nanostructures are very promising techniques and open a gateway for visualizing nanostructures.     

Synthesis of TiO<Subscript>2</Subscript> nanotubes using different alkaline media and their applications in photocatalysis and DSSCs

TiO₂ nanotubes (TNTs) were successfully synthesized from different alkaline media (i.e., NaOH and KOH) by using a microwave hydrothermal process. The effects of different alkaline media on the formation of TiO₂ nanotubes and their physicochemical properties were investigated. The phases of different TiO₂ nanostructures were studied by using X-ray diffraction patterns. Morphologies of the nanostructures were observed with a transmission electron microscope. The optical properties of the nanostructures were evaluated through the absorption behavior using UV–Vis diffuse reflectance spectroscopy. The photocatalytic activities of the TiO₂ nanostructures were evaluated by the degradation of methylene blue aqueous dye solution under the simulated solar light irradiation. Similarly, the photovoltaic efficiencies of the prepared samples were investigated by making photo-anode layers in the Dye Sensitized Solar Cells (DSSCs). The results revealed that in comparison to the single layered TiO₂ nanostructures in the DSSC, creation of a double layer structure significantly enhanced the efficiency of DSSC.