bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multifunctional nanocomposite transparent UV-blocking films sythesized by sol-gel process for optical, automotive and aeronautic applications
Authors: Ayalasomayajula Phani Ratna , Santucci S. 
Published: April 2011

AbstractDevelopment of UV blocking thin films with effective cut-off features with steep edges and high transmission in the visible and IR region have been developed. The unique optical, mechanical and chemical properties of silica and ceria nanocomposites with surface functional groups making them most promising candidate for applications in opto-electronic, automotive, and aeronautic industries. On the other hand, highly hydro and oleophobic films are being actively considered in optical, automotive and aeronautic industries to increase adhesion and scratch, abrasion resistance properties. In order to fill the gap, and fulfill the requirements to meet both ends, it could be proved that morphological changes in the nanometer range influences the water contact angles and their hystersis of low energy materials. Nanocomposite films of SiO2 and CeO2 with surface functionalisation with decafluorooctly-triethoxy silane itself forms nano-hemispheres (similar to lotus leaf) at and above 100°C favoring an increase in water contact angle from 122° (25°C) to 145°(400°C). The structural, optical, and hydrophobic properties have been examined by employing X-ray diffraction, UV-visible spectroscopy, contact angle techniques, respectively. The cut-off behavior of the deposited and annealed nanocomposite thin films have been tuned by varying different amounts of CeO2 in SiO2.
Effect of Diameter on Electron Field Emission of Carbon Nanotube Bundles
Authors: McClain Devon , DeRoss Mason , Tavan Noel , Jiao Jun , McCarter Coralee M , Richards Robert F , Mesarovic Sinisa , Richards Cecilia D , Bahr David F 
Published: April 2011

AbstractArrays of multi-walled carbon nanotunbe (CNT) bundles were fabricated on silicon [100] substrate with iron-nitrate sol-gel catalyst patterned via standard photolithographic techniques. Nanotube bundles with diameters ranging from 400µm to 15µm were grown in a chemical vapor deposition reactor and electrically characterized using a scanning-anode probe apparatus. Results showed a relatively low number of graphitic layers in individual nanotubes and a definite increase in field emission performance with decreasing bundle diameter. A 400µm wide matt of CNTs yielded a turn-on field of 6.7 V/µm and field enhancement of 602 while 15µm bundles performed significantly better with turn-on fields of 1.6 V/µm and field enhancement factors of 2425. The overall trend strongly suggests that the field emission character of CNT based aggregate structures such as those presented here is proportional to their aspect ratio.
Novel Synthesis of Gold Nanoparticles in Aqueous Media
Authors: Sugunan Abhilash , Dutta Joydeep 
Published: April 2011

AbstractAqueous synthesis of glutamate functionalized single crystal gold nanoparticles was achieved by reducing a solution of chloroauric acid with monosodium glutamate. Highly uniform size distributions of the nanoparticles can be obtained by having an excess of monosodium glutamate in the starting solution. Similar to the conventional synthesis of gold nanoparticles by reduction of chloroauric acid with trisodium citrate, the obtained particle sizes were varied in the range of 14 – 25 nm without loosing the uniformity in its size distribution by varying the concentration of the reducing agent.
Self Assembly of Anisotropic Organic Molecules: Diffusion versus Sticking Anisotropy
Authors: Berkebile Stephen , Koller Georg , Hlawacek Gregor , Oehzelt Martin , Resel Roland , Netzer Falko P. , Ramsey Michael G. 
Published: April 2011

AbstractThe molecular/crystal orientation and morphology of active molecular structures is a key determinant for the function of nanoscaled organic devices. In π-conjugated systems, both charge transport and optical properties will strongly depend on the molecular orientation due to the highly anisotropic charge carrier mobility in these organic crystals and the anisotropic absorption and luminescence behavior of the molecules. Although the importance of organic on inorganic interface formation and thin film growth is widely acknowledged, little is known regarding the growth kinetics. A better understanding of the processes driving molecular self-assembly is necessary if the self-assembly process is to be controlled. Moreover, it is interesting as the anisotropy of the molecular building blocks presents a fundamental difference from what is known from inorganic growth. Here we show that either sticking or diffusion anisotropy can control the growth depending on preparation conditions. This is illustrated by an investigation into the growth of sexiphenyl (6P) on the anisotropic TiO2(110)-(1×1) surface for temperatures between 80K and 400K using in-situ UHV photoemission, x-ray absorption spectroscopy, synchrotron x-ray diffraction and ex-situ atomic force microscopy. For 6P adsorption even at 80K we found that the molecules orient parallel to the TiO2 oxygen rows and form small crystallites. At 300K this molecular orientation is retained and large micrometer sized 6P(203) oriented needles running perpendicular to oxygen substrate rows are formed. In contrast, for growth at elevated temperatures the 6P molecular axis is near perpendicular to the surface and large islands elongated parallel to the substrate rows are formed. These differences in crystallite orientation and morphology can be explained by the domination of the growth kinetics by either sticking or diffusion anisotropy depending on growth temperature.
Fabrication and Defect Designs on DNA Linked 2-D Colloidal Photonic Crystals Using a Nd:YAG Pulsed Laser
Authors: Asmatulu Ramazan , Kim Sejong , Bright Robin , Yu Phillip , Papadimitrakopoulos Fotios , Marcus Harris 
Published: April 2011

AbstractControlled defects were created on DNA linked 2-D colloidal photonic crystals using a Nd:YAG pulsed laser. The 2-D photonic crystals were self-assembled using 1.8 μm polystyrene (PS) microspheres on functionalized glass substrates. To synthesize the hexagonal close packed crystalline samples, both substrate and particles attached single-strand DNA, sequence A on the substrate and sequence B on the particles. The DNA was hybridized using the DNA linker with complementary single-strand A’B’ that anchored the particles to the substrate during self-assembly. The 532 nm second harmonic wavelength beam of the pulsed Nd:YAG laser (1064 nm) with a pulse width of 10 ns was used for the removal of individual colloidal particles from the self assembled photonic crystals. In the present tests, the diameter of the laser beam was optically reduced from 7 mm to about 1.8 μm. Controlled line defects and geometrical shapes (e.g., hexagonal and triangle) were created in the 2D arrays in an aqueous medium.
Nanostructured Ceramic Film Formation on Self-Assembled Monolayers via a Biomimetic Approach
Authors: Cho Junghyun , Blom Douglas A. , Coffey Dorothy W. , Allard Lawrence F. , Cho Junghyun 
Published: April 2011

AbstractA biomimetic approach is employed to deposit ceramic films on organic self-assembled monolayers (SAMs) coated substrates. Specifically, zirconia (ZrO2) films are grown in a zirconium sulfate precursor solution at near room temperatures (∼70°C). This process, directed by the nanoscale organic template, mimics the controlled nucleation and growth of the biominerals such as bones and teeth. The resultant zirconia films consist of nanosized particles (5-10 nm) that are precipitated out in a supersaturated precursor solution. Cross-sectional TEM and STEM works were performed to quantitatively analyze the film structure and chemistry, as well as interfacial region of the ceramic-SAM films. A stepwise deposition process was developed to avoid excessive formation of aggregation. Further, the dynamic nanoindentation testing was employed to assess the thickness and film-only intrinsic mechanical properties for direct comparison among the films processed with different processing parameters and microstructures. The films with finer particulate structure displayed higher intrinsic modulus than did those with coarser structure.
A General Route to Nanoparticle Thin Films and Coatings
Authors: Mukherjee Bratindranath , Narayanan Ravishankar 
Published: April 2011

AbstractNanoparticles thin films have wide range of applications such as nanoelectronics, magnetic storage devices, SERS substrate fabrication, optical grating and antireflective coating. Present work describes a method to prepare large area nanoparticles thin film of the order of few square centimeters. Thin film deposition has been done successfully on a wide range of conducting as well as non conducting substrates such as carbon-coated copper grid, silicon, m-plane of alumina, glass and (100) plane of NaCl single crystal. SEM, TEM and AFM studies have been done for microstructural characterization of the thin films. A basic mechanism has been proposed towards the understanding of the deposition process.
Pulsed Laser Deposition of Cluster-Assembled Thin Films with Controlled Nanostructure
Authors: Li Bassi Andrea , Casari Carlo Spartaco , Di Fonzo Fabio , Bailini Alessandro , Fusi Matteo , Dellasega David , Russo Valeria , Baserga Andrea , Cattaneo Diego , Bottani Carlo Enrico 
Published: April 2011

AbstractThin films synthesized by assembling clusters present interesting chemical and physical properties and a large specific surface, and are appealing for functional applications (e.g. sensing and catalysis). Also, clusters supported on surfaces are interesting both for nanocatalysis applications and for fundamental research. By means of pulsed laser deposition (PLD) in a background atmosphere we can induce cluster aggregation in the ablation plume and control the deposition kinetic energy of the clusters. These phenomena depend on the plume expansion dynamics and their influence on the properties of the deposited films has been investigated as a function of the background gas mass and pressure. The control of these parameters permits variation of the film surface morphology, from a compact structure with a very smooth surface, to a film with a controlled roughness at the nanoscale, to an open, low density meso- and nanostructure characterized by a high fraction of voids and by a large specific area. Thin films of WOx, TiOx, Pd/PdO, and Ag were deposited and characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM) and Raman spectroscopy. Post-deposition annealing permits control of the crystalline degree of the films, which in the case of tungsten and titanium oxide is found to depend on the original nanostructure, while a different degree of oxidation can be induced by controlling the amount of oxygen in the deposition chamber. In-situ scanning tunneling microscopy (STM) was employed to study the first stages of growth of W films on different substrates. This opens the possibility to tailor the material properties through the control of the building nano-units.
Ordered and Parallel Niobium Oxide Nano-Tubes Fabricated using Atomic Layer Deposition in Anodic Alumina Templates
Authors: Rooth Mårten , Johansson Anders , Boman Mats , Hårsta Anders 
Published: April 2011

AbstractAmorphous niobium oxide (Nb2O5) nano-tubes were fabricated inside anodic alumina templates using atomic layer deposition (ALD). The nanoporous templates were in-house fabricated anodic alumina membranes having an inter-pore distance of about 100 nm with pores lengths of 2 µm. The pores were parallel and well ordered in a hexagonal pattern. Atomic layer deposition was performed using gas pulses of niobium iodide (NbI5) and oxygen separated by purging pulses of argon. By employing long gas pulses (30 s) it was possible to get coherent and amorphous Nb2O5 films conformally covering the pore-walls of the alumina template. The outer diameter of the nano-tubes was tailored between 40 and 80 nm by using alumina templates with different pore sizes. By using template membranes with pores not opened in the bottom, nano-tubes with one side closed could be fabricated. Free-standing, and still parallel, nano-tubes could be obtained by selectively etching away the alumina template using phosphoric acid. Using the above mentioned procedure it was possible to fabricate unsurpassed parallel niobium oxide nano-tubes of equal length, diameter and wall-thickness, ordered in a perfect hexagonal pattern. The samples were analysed using high resolution scanning electron microscopy (HR-SEM), transmission electron microscopy (TEM), electron diffraction and x-ray fluorescence spectroscopy (XRFS).
The Self-Assembling “Grow-in-Place” Process: An Environmentally Friendly Approach to Nanowire Device Fabrication
Authors: Shan Yinghui , Kalkan Ali Kaan , Fonash Stephen J. 
Published: April 2011

AbstractSilicon nanowires (SiNWs) were fabricated directly from the Si source gas into pre-fabricated permanent nanochannel templates by our self-assembling “grow-in-place” approach. The size, shape, position, orientation, and number of the SiNWs can be precisely controlled by the pre-fabricated nanochannel templates. Our approach is environmentally benign and friendly since only the exact number of SiNWs needed was grown and the SiNWs were always confined in the nanochannel templates. In addition, the templates can be fabricated with built-in contacts and integrated into the final devices, providing contacts, interconnects, and passivation/encapsulation. We are developing a variety of built-in ohmic and rectifying contact structures and approaches for the “grow-in-place” methodology. Some initial results will be discussed here.
Size- and Surface-dependent Photoresistance in SnO2 Nanowires
Authors: Mathur Sanjay , Barth Sven , Pyun Jae-Chul , Shen Hao 
Published: April 2011

AbstractNanostructured one-dimensional materials, such as nanowires, tubes and rods, are gaining increasing attention due to interesting properties and confinement effects, however controlled synthesis of these structures is still limited to a few methods. We present here the synthesis of SnO2 nanowires (Ø, 50 – 1000 nm) at moderate temperatures (550 – 900 °C) using a molecular source [Sn(OBut)4] with pre-existent Sn-O bonds. The growth occurs via a catalyst driven vapor-solid-solid mechanism. Size-selective synthesis of NWs in high areal density was achieved by choosing Au particles of appropriate size. HR-TEM analysis reveals the single crystalline behaviour of wires with a preferred growth direction [100]. Use of SnO2 nanowires as potential optical switches for UV applications was demonstrated by the photo-response measurements. Determination of band gap values confirmed the blue-shift of the main photo-response peak with shrinking radial dimensions of the wires. Furthermore, deposition of vanadium oxide onto SnO2 led to a red-shift of the main conduction value of the nanowires.
PbS Nanocrystal “Plasma-Polymerization”
Authors: Cademartiri Ludovico , von Freymann Georg , Arsenault Andre C. , Bertolotti Jacopo , Wiersma Diederik S. , Kitaev Vladimir , Ozin Geoffrey A. 
Published: April 2011

AbstractWe here demonstrate the use of semiconductor chalcogenide nanocrystals as single-source precursors for the one-step formation of flexible functional films. By taking advantage of the surface chemistry of these “zero-dimensional” building blocks we obtain close-packed three-dimensional arrays of nanocrystals interconnected by oxide sheaths. The films are obtained by exposing oxidation-resistant nanocrystals to an air plasma treatment. This treatment does not significantly influence the photoluminescence efficiency of the individual nanocrystal building blocks but confers them resilience to bending as well as resistance to acidic environments, hot solvents, annealing, and UV irradiation.
Directed Self-Assembly of Multilayer Thin Films of ZnS and Gold Nanoparticles by Modified Polyelectrolyte Deposition Technique
Authors: Jafri S. H. M. , Sharma A. B. , Thanachayanont Chanchana , Dutta Joydeep 
Published: April 2011

AbstractFabrication strategies based on mechanisms of self-assembly are now widely being recognized as inevitable tools in nanotechnology. Self-organized construction of advanced materials and devices may be done starting with tailor made nanoparticles as building blocks. Multilayer thin films of gold, zinc sulphide and manganese doped zinc Sulfide nanoparticles were fabricated by a modified polyelectrolyte deposition process. A prerequisite to utilization of colloids for the fabrication of uniform layers is that they remain in suspension and resist unwanted agglomeration. The stability of colloids is generally achieved either by electrostatic stabilization, involving the creation of an electrical double layers arising from ions intentionally adsorbed on the surface of the particle and associated counter ions that surround the particle, or by steric hindrance that is achieved by the adsorption of macromolecules on the surface of the particles. The inherent necessity to introduce electrostatic or steric hindrance to avoid colloidal agglomeration was utilized to induce self-assembly of multilayers applying similar concept used for the layering of polyelectrolytes. Polyacrylic acid was used as the polyanion and chitosan as the polycation for the deposition process. Upto 100 layers of nanoparticles were constructed and films that were found to be stable and uniform over the substrate. The layer-by-layer deposition of multilayers of several different structures was prepared and devices showing resistive and capacitive electrical characteristics have been fabricated. The onset of electrical conduction in the resistive devices could be varied by introducing a dielectric interlayer between gold nanoparticles and by introducing a gold overlayer on the zinc sulphide nanoparticle devices.
Carbon nanotubes and nanostructures grown at below 400°C
Authors: Chen Guan Yow , Poa P.C.H. , Henley S.J. , Stolojan V. , Silva S.R.P. 
Published: April 2011

AbstractIn this paper, we report clear evidence for the growth of carbon nanotubes and nanostructures at low substrate temperatures, using direct-current plasma-enhanced chemical vapour deposition. The catalyst particles are mounted on a titanium layer which acts as a thermal barrier, and allows for a larger temperature gradient between the Ni catalyst surface and the substrate. A simple thermodynamic simulation shows that the temperature differential between the substrate growth surface and the growth electrode is determined by the thickness of the titanium layer. This facilitates the growth of nanotubes, as opposed to nanofibres with herring-bone or amorphous structures. The growth properties are discussed as a function of the bias voltage and hydrocarbon concentration. The heating during growth provided solely by the plasma is below 400°C and is dependent on the process conditions and the electrode configuration in the growth chamber. These conditions need to be taken into account when comparing processes across different growth methods and instruments. The novel approach based on the use of a thermal barrier ensures the synthesis of carbon nanotubes at room temperature substrate conditions, which can be attained with a suitable cooling scheme.
Effects of strain on the resonant Raman profile of metallic
Authors: Souza Filho Antonio G , Kobayashi N , Jiang Jie , Saito Riichiro , Cronin Stephen B , Mendes Filho Josue , Samsonidze Ge G , Dresselhaus Gene , Dresselhaus Mildred S 
Published: April 2011

AbstractIn this paper we report the effects of strain on the electronic properties of single wall carbon nanotubes and its consequence on the resonant Raman cross section. A quantum interference effect has been predicted for the radial breathing mode spectra for metallic tubes. For metallic tubes, the lower and upper components of Eii resulting from the trigonal warping effect are affected differently and for low chiral angle they cross for some strain value. Near (at) the crossing point, the resonant Raman spectra profile exhibits a maximum (minimum) value due to a quantum interference in the Raman cross section. This Raman cross section interference effect was observed in Raman experiments carried out on isolated SWNTs. The Raman experiment performed on an isolated strained metallic SWNT supports our modeling predictions.
Analysis of the Samples of Fe-Cu-Nb-Si-B Amorphous Alloys Obtained by Dynamic Compacting Method
Authors: Golubev Victor A. , Strikanov Andrey V. , Potemkin Grigory A. , Zueva Ludmila V. , Golubev Aleksey V. , Olenina Eleonora V. , Bugrov Vladimir G. , Sten’gach Aleksey V. , Faehl Rickey J. 
Published: April 2011

AbstractThe Dynamic Compacting (DC) method is promising method to produce considerable-size nonporous wares. The phenomenon is based on the impact of shock wave on the initial powders of amorphous alloys. Every time when the shock wave propagates through the bulk of substance then the temperature rises substantially. Therefore there is a need of study of the DC’s effect on the structure and properties of the amorphous alloys. The results of the thermal analysis (in particular, Differential Scanning Calorimetry) of the samples of the soft magnetic alloys are presented in the report. These results concern with amorphous alloys of 5BDSR, GM414, 10NSR trademarks before DC and after DC, respectively. It is shown there is single low-temperature endothermic peak (near 300C) and there are several high temperature exothermic peaks (near 540C, 650C, and 700C). The first peak is related to glass-transition, the following peaks are related to formation of nano-crystalline phases. It was proved by XRD analysis data. The optimal regimes of the thermal processing of final wares were chosen on the base of thermal- and XRD-analysis. The study of the effects of these regimes on the properties (magnetic conductivity, specific losses etc.) of the circular magnetic conductors was executed. In particular, thermal- as well as thermo-magnetic processing of magnetic conductors based on 5BDSR amorphous alloy (after DC) essentially improves their magnetic properties. For example, magnetic conductivity fÝ increases approximately by factor 17 with respect to the magnitude before DC.
Dynamic Compacting of Powders of Some Amorphous Alloys
Authors: Golubev Victor A. , Strikanov Andrey V. , Golubev Aleksey V. , Bugrov Vladimir G. , Potemkin Grigory A. , Kudel’kin Valery B. , Mochalov Mikhail A. , Faehl Rickey J. 
Published: April 2011

AbstractAt present amorphous metallic alloys have the broad expansion in various fields of science&engineering as a result of their unique properties. In particular, soft magnetic amorphous alloys are extensively used in electrical engineering. However the production of considerable-size nonporous wares based on the powders (or tapes) of these alloys is heavy problem owing to high hardness of the particles. Therefore shock wave’s compacting or Dynamic Compacting (DC) method is promising one to produce the wares on the base of powders of amorphous alloys because it can provides high strength and near zero porosity of the wares. The experimental D-U diagrams of soft magnetic amorphous alloys were obtained to realize this method of compacting. The calculations of the amplitude and duration of shock wave were carried out. The several versions of explosive devices using shock plane wave generator to produce circular magnetic conductors were developed and were tested. These magnetic conductors are based on amorphous alloys of 5BDSR, GM414, 10NSR trademarks (Fe with Cu, Nb, Si, B additives). XRD analysis proved that amorphous state of the alloys remains the same up to 20 GPa shock wave’s pressures. The mechanical, structural, electrical and magnetic properties both initial amorphous alloys and compacted one were obtained and compared as a result of the implemented works. It was stated that DC leads to increase of magnetic conductivity by factor ∼15 with respect to initial amorphous alloys powder. Besides the specific losses decrease in ∼4 times.