bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermodynamic Modeling of Surface Segregation in Au-Ti Nanoparticles
Authors: Jayaganthan Rengaswamy , Chow Gan Moog
Published: March 2009

The surface composition of nanoparticles is generally different from the average or bulk composition; this phenomenon is commonly referred to as surface segregation. In the present work, the surface segregation in Au-Ti nanoparticles has been analyzed based on a thermodynamic model that incorporates the size effect into the quasichemical model. The calculated surface compositions of Au-Ti nanoparticles are compared with that of the bulk Au-Ti alloys.
Tribological Characteristics of Nanocrystalline Copper
Authors: Shanthi M. , Lim C.Y.H. , Gupta Manoj
Published: March 2009

In the present study, two sets of powder metallurgy copper samples, with grain sizes of 99 nm and 63 nm, respectively, were investigated under different tribological conditions. The wear behavior of these materials was studied through a pin-on-disc configuration using sliding velocities of 0.5, 1 and 2 m/s with normal loads of 10 and 30 N. The finer-grained copper was able to outperform (by between 4- to 16-fold) its coarser-grained counterpart under severe test conditions, but no advantage was observed when conditions were milder. Scanning electron microscopy revealed the dominant wear mechanisms to be oxidative wear under mild sliding, with a transition to adhesive wear with increases in sliding speed and normal load.
Growth of Zinc Oxide Nanowires and Nanobelts for Gas Sensing Applications
Authors: Hossain M.K. , Ghosh S.C. , Boontongkong Y. , Thanachayanont Chanchana , Dutta Joydeep
Published: March 2009

Zinc Oxide (ZnO) is a very useful as a solid state gas sensor material. In chemical sensing the surface and interface interactions between the analyte molecules and the sensing material is all but important that is read through the changes in electrical conductance. In that sense, nano-objects with a large surface atom/bulk atom ratio, like nanoparticles and nanowires, are potentially the best chemical sensors. The mechanism envisioned involves the adsorption (and eventually diffusion) of the analyte molecule at the surface that induces a change in the electrical resistance of the nano-object. The most convenient way to measure
changes in electrical resistance in such devices is to obtain the specific material as
nanowires or as connected nanoparticles. Here, we will discuss about a low-temperature wet-chemical process of synthesizing ZnO nanoparticles, nanowires and nanobelts for application as gas sensors.
Electrochemical Combustion of Phenol at the Carbon Nanotube Electrode
Authors: Hu C.G. , Wang W.L. , Feng Bo
Published: March 2009

The carboxyl modified carbon nanotubes were obtained by treating them in the
concentrated nitric acid with a little surfactant. The complete electrochemical combustion of phenol has been found under 5 M at the carboxyl modified carbon nanotube electrode in phosphate buffer solution. The reaction was discussed in details. Due to the porous tubule of the structure of the carbon nanotube and large quantity of hydroxyl exists in the carboxyl modified carbon nanotube electrode, which were necessary for the continually electrochemical combustion of phenol. Long time potentiostatic oxidation showed that the phenol could be eliminated from the aqueous media without any foul at the carbon nanotube electrode.
Experimental Investigation and Monte Carlo Simulation of Glass Transition in Polymer Nanocomposites
Authors: Jayaganthan Rengaswamy , Vora Rohitkumar H.
Published: March 2009

The glass transition temperature (Tg) of Fluoro-Poly(ether-imide) and Fluoro-Poly(either-Imide)/MMY clay Nanocomposites has been investigated by both experiments and Monte Carlo Simulation. It was observed that the (Tg) values of the nanocomposites increases with increase in clay contents.
Layer Structured Calcium Bismuth Titanate by Mechanical Activation
Authors: Sim M.H. , Xue J.M. , Wang J.
Published: March 2009

Nanocrystalline calcium bismuth titanate (CaBi4Ti4O15), which exhibits a layer structure, has been successfully synthesized by mechanical activation of constituent oxides of CaO, Bi2O3 and TiO2 in a nitrogen atmosphere at room temperature. The phase-forming calcination at elevated temperatures that is always required is skipped. CaBi4Ti4O15 derived from mechanical activation consists of nanocrystallites, which occur as aggregates of ~50 nm in sizes. It demonstrates an
improved sinterability and was sintered to a density of 93.4% theoretical density at 1175oC for 2 hours. Ferroelectric properties of sintered CaBi4Ti4O15 derived from mechanical activation have been studied. A peak dielectric constant of 1049 at the Curie temperature of 774oC was measured at 1MHz for CaBi4Ti4O15 sintered at 1175oC.
Preparation of Single-Crystal BiOCl Nanorods via Surfactant Soft-Template Inducing Growth
Authors: Cao Chuan Bao , Lv Ruitao , Zhu He Sun
Published: March 2009

Nanorods of a compound semiconductor, BiOCl, have been prepared from BiCl3 solutions containing a nonionic surfactant, t-octyl-(OCH2CH2)xOH, x=9, 10 (Triton X-100). Powder X-ray diffraction (XRD) pattern indicated that the product was pure tetragonal phase bismoclite (BiOCl). The product was also characterized by the techniques of scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS) and transmission electron microscope (TEM). The as-obtained BiOCl nanorods possess mean diameters less than 40nm and lengths ranging in 160-400nm. Selected area electron diffraction (SAED) pattern showed the single-crystal nature of as-prepared BiOCl nanorods. The growth mechanism of BiOCl nanorods has also been proposed.
Synthesis and Characterization of Nanoscale CeO2 Catalyst for deNOx
Authors: Kawi S. , Tang Y.P. , Hidajat K. , Yu L.E.
Published: March 2009

Hydrothermal and precipitation methods have been applied to synthesize nanoscale CeO2 catalysts for selective catalytic reduction of NO with hydrocarbon under oxygen-rich condition. The former procedure has the advantage of enhancing the hydrothermal stability of nanomaterial. BET results show that their surface areas are about 30-80 m2/g. Based on TEM results, hydrothermally prepared CeO2 shows very uniform grain shaped particles with size around 10-20 nanometers. Its thermal stability up to 1200°C has been confirmed by in-situ XRD. Furthermore, deNOx reaction with propene as reducing agent in the presence of 5% oxygen has been carried out to compare catalysts prepared by the above two methods. Results show that hydrothermally prepared catalyst is more active than the one prepared by precipitation method. The latter one lost half of its activity in the presence of 5% water vapor, while the former one could stand up to 10% water vapor in the gas
mixture without losing much activity.
Synthesis, Characterization and Adsorption Properties of ETS-4 Molecular Sieve
Authors: Marathe R.P. , Mantri K.
Published: March 2009

ETS-4 with a Si:Ti ratio of 10:1 has been successfully synthesized in our
laboratory and its characterization was done using X-ray diffraction (XRD) and scanning electron microscope (SEM). The thermal behavior was studied by thermogravimetric analysis (TGA). The synthesized crystals were pelletized under high pressure without any binder. Thus the pellets have a bidispersed pore structure – intracrystalline macropores and crystal micropores of the order of 0.4 nanometers. Equilibrium isotherms of oxygen, nitrogen and methane on the ETS-4 sample were measured volumetrically. The capacity compares favorably with that of a commercially available adsorbent of similar pore size. Langmuir isotherm fits well to the experimental equilibrium data.
Synthesis, Structural and Mechanical Characterization of Amorphous and Crystalline Boron Nanobelts
Authors: Ni Hai , Li Xiao Dong
Published: March 2009

Amorphous and crystalline (rhombohedral structure with [111] growth direction) boron nanobelts were synthesized by the vapor-liquid-solid technique. Their structure and chemical compositions were studied by various electron and atomic force microscopy techniques. Most amorphous and crystalline belts have a width to thickness ratio of 2 and are covered with a layer of amorphous silicon oxide. The crystalline belt cores are defect-free single crystals. Gold catalyst thickness and synthesis temperature are the two prominent parameters determining structure of the synthesized nanobelts. The elastic modulus and hardness were measured using nanoindentation and atomic force microscopy three-point bending techniques. The indentation elastic modulus and hardness were measured to be 92.84.5 GPa and 8.40.6 GPa for amorphous belts, and 72.73.9 GPa and 6.80.6 GPa for crystalline ones, respectively. The three-point bending elastic moduli were found to be 87.83.5 GPa and 72.22.4 GPa for amorphous and crystalline, respectively. The measured mechanical properties are 4-5 times lower than those of the counterpart bulk materials.
Orientation Preferred Structures in BaTiO3 Thin Films on Ni Substrates
Authors: Jiang Jiechao , Meletis Efstathios I. , Yuan Z. , Liu Jian , Weaver Jenny , Chen Chong Lin , Lin B. , Giurgiutiu V. , Guo R.Y. , Bhalla A.S. , Liu D. , White K.W.
Published: March 2009

We report the fabrication of the orientation preferred structures in BaTiO3 thin films on Ni substrates using pulsed laser deposition. Transmission electron microscopy studies showed that the films consist of crystalline structures of tetragonal BaTiO3. More than 60% of BaTiO3 grains in the films exhibit nearly the same crystallographic orientation with their a-axis lying in the film plane and the [011] direction parallel to the growth direction. Such orientation preferred structures were grown on a Ni nanocrystalline buffer layer. This result demonstrated the possibility of approximating an oriented single crystalline ceramic oxide structures on metallic substrates.
Thermochromic Coatings for Intelligent Architectural Glazing
Authors: Parkin Ivan P. , Binions Russell , Piccirillo Clara , Blackman Christopher S. , Manning Troy D.
Published: March 2009

Thermochromic glazing is a type of intelligent glazing; one where the properties of the glazing change according to some external stimulus. More particularly a thermochromic window is a device that changes its transmission and reflectance properties at a critical temperature (Tc). Atthis specific temperature the material undergoes a semi-conductor to metal transition. At temperatures lower than Tc the window lets all of the solar energy that hits it through. At emperatures above Tc the window reflects the infra-red portion of solar energy. In such a way thermochromic windows may help reduce air conditioning and heating costs leading to more energy efficient buildings. This review details the nature of the semi-conductor to metal transition and indicates how substitutional doping within a crystal lattice can be used to manipulate and fine tune the critical temperature. Also detailed is the underlying science and methodologies so far employed in the production of thermochromic thin films.
Synthesis and Magnetic Properties of Nanosized Cobalt Substituted Nickel Ferrites (Ni1-xCoxFe2O4) Using Egg White (Ovalbumin) by Thermal Evaporation
Authors: Marutha Senthil S. , Jayaprakash R. , Singh V.N. , Mehta B.R. , Govindaraj G.
Published: March 2009

An attempt has been made to synthesize Ni1-xCoxFe2O4 by a simple technique of thermal evaporation with the help of egg white. The use of egg white (ovalbumin) in the synthesis process mainly helps to shape the particle during the reaction. The X-ray diffraction patterns reveal that the synthesized Ni1-XCoxFe2O4 ferrites are in nanocrystalline phase. The transmission electron microscopy observation confirmed that the average particle size of Ni1-xCoxFe2O4 has been varied from 7 nm to 30 nm. EDX spectrum gives account of the percentage composition of the products such as nickel, cobalt, Fe and O. Vibrating Samples Magnetometer (VSM) have been sued to study the saturation magnetization for variation of Ni substitution over CoFe2O4 and the influence of particle size in magnetic properties. Its analysis is based on the aspect of variation in coercivity with temperature. The FTIR spectra of the sample in the range 400 – 4000 cm-1 reveals the common feature of ferrites like high frequency band to the tetrahedral and low frequency band to the octahedral stretching vibrations.
The Answer to the Challenging Question: Is there a Size Limit of Nanowires?
Authors: Hourlier Djamila , Perrot Pierre
Published: March 2009

Our present analysis will focus on the S(V)LS mechanism. In the S(V)LS process, silicon nanowires are grown by heating the metal-coated silicon substrate at high temperature in an argon and hydrogen atmosphere. Here, we demonstrate the origin of the driving force needed for the metal supersaturation and calculate the binary phase diagrams of Au-Si nanosystems involved in the growth of nanowires. These new diagrams can be used for other purposes helping to improve the understanding of the physical properties of nanostructures. We also answer the challenging question that many researchers have addressed on whether a minimum size limit of silicon nanowires exists. The nanowire size limit has been evaluated on the basis of thermodynamics and using silicon nanowires obtained via the S(V)LS rather than the VLS mechanism. At 1100°C, the temperature commonly used for the growth of nanowires by the S(V)LS mechanism, it has been found that there is no minimum size limit of nanowires.
Controlling Synthesis of Copper Nanorods and Triangular Nanoplates
Authors: Zheng Xiu Wen
Published: March 2009

Copper nanorods and triangular nanoplates have been successfully generated by via a simple solution-phase approach by reducing CuCl2 with L-ascorbic acid (AsA) in aqueous solution in the presence of cetyltgrimethlammonium bromide (CTAB). The formation of self-assembled microstructures of CTAB molecules in aqueous solution is suggested to account for the anisotropic growth of one-dimensional copper nanorods and triangular nanoplates.
Solution Processing Route to High Efficiency CuIn(S,Se)2 Solar Cells
Authors: Guillemoles J.F. , Connolly J.P. , Ramdani O. , Roussel O. , Guimard D. , Bermudez V. , Naghavi N* , Grand P.P. , Parissi L. , Kurdi J. , Kessler J. , Kerrec O. , Lincot D.
Published: March 2009

Inorganic semiconductors have properties that are notoriously difficult to control due to the deleterious impact of crystalline imperfections, and this is especially so in solar cells. In this work, it is demonstrated that materials grown using wet chemistry processes for the preparation of nanocristalline precursors can achieve the same performance as the best state of the art, namely conversion efficiencies above 11% with CuInS2. Interestingly, due to the growth process, the active material inherit a porous morphology that is shown to play a part in the performance and functionality of the active material. The new device morphology leads to a device operation closer to that of nanoscale organic interpenetrated solar cells or dye sensitized solar cells than to those of standard polycrystalline ones.
Computational Study of Organometallic Structures for Hydrogen Storage, Effects of Ligands
Authors: Martinez Arturo I.
Published: March 2009

Density functional theory calculations of hydrogen storage capacity for different organometallic structures have been carried out. Complexes involving Sc, Ti and V bound to C4H4, C5H5, C5F5 and B3N3H6 molecules have been considered, and all present a hydrogen storage capability limited by the 18-electron rule. In order to stabilize the complexes, which the 18-electron rule is not completed, additional ligands are considered, namely -H, -CH3, -NH2, -OH and -F. These ligands affect the H2-metal bond; particularly the back donation effect from the metal atom to the * antibonding state of H2 and then its H2 storage capacity.
Effects of Morphology on the Electronic Properties of Hydrogenated Silicon Carbide Nanowires
Authors: Miranda A. , Cuevas J.L. , Ramos A.E. , Cruz-Irisson Miguel
Published: March 2009

The effects on the electronic band structure of hydrogenated cubic silicon carbide (-SiC) nanowires of changes in the diameter and morphology are studied using a semiempirical sp3s* tight-binding approach applied to a supercell model. The results of the calculation of the electronic band structure and electronic density of states obtained are compared with those calculated by density functional theory within local density approximation only for the bulk of -SiC. As boundary conditions, we passivated all the Si and C dangling bonds with hydrogen atoms. The results show that although surface morphology modifies the band gap, the change is more systematic with the thickness variation. The energy band gap increases with decreasing diameter in all cases because of quantum confinement, but the scaling is dependent on the morphology (cross-section) of the -SiC nanowires. Finally, the calculations show a consistent asymptotical behavior to the crystalline limit when the width of the wires enlarges.
Biocompatibility of Zinc Aluminate Nanostructured Material
Authors: Alvarez-Pérez M.A. , García-Hipolito M. , de La Fuente Hernández J. , Arzate H. , Carmona-Rodriguez B. , Ximenez-Fyvie L.A. , Juarez-Islas J.A. , Alvarez-Fregoso O.
Published: March 2009

We have used zinc aluminate nanostructured films deposited by spray pyrolysis to determine its biocompatibility assessed by cells attachment and cell differentiation. Cell attachment onto zinc aluminate showed an increase of 53, 81 and 86% at 180, 300 and 420 minutes (p<0.05) when compared to controls. Mineralization was analyzed at 5 and 14 days of culture by scanning electron microscopy, microanalysis and atomic force microscopy. Our results showed in experimental culture a higher density of mineral-like tissue with small needle-shaped crystal and granular nanoparticles with preferential orientation when compared to controls. The composition of the mineral-like tissue deposited in zinc aluminate nanostructured material had a Ca/P ratio of 1.6, whereas control culture had a Ca/P ratio of 1.50. Our finding revealed that ZnAl2O4 promoted higher expression of type I collagen, bone sialoprotein, osteocalcin and alkaline phosphatase, suggesting that zinc aluminate provides a microenvironment that favors mineral formation and cell differentiation. Our results point to the potential use of ZnAl2O4 for the osteoinductive process in biomedical implants.
Influence of Argon Flow on Deposition of Hydrogenated Nanocrystalline Silicon (nc-Si:H) Films by Plasma Chemical Vapor Deposition
Authors: Funde A.M. , Bakr N.A. , Salve T.S. , Diwate K.D. , Kamble D.K. , Hawaldar Ranjit R. , Amalnerkar Dinesh , Jadkar Sandesh R.
Published: March 2009

In this work we report synthesis and characterization of hydrogenated nanocrystalline silicon (nc-Si:H) thin films by plasma chemical vapor deposition (P-CVD) method at 200 0C on glass substrates. Film properties are carefully and systematically investigated as a function of argon (Ar) flow rate. Characterization of these films with Raman spectroscopy revealed that the addition of Ar into SiH4-H2 plasma endorses the growth of crystallinity in the films. The Fourier transform infrared (FTIR) spectroscopic analysis showed that with increasing Ar flow rate the hydrogen bonding in the films shifts from mono-hydride (Si-H) to di-hydride (Si-H2) and (Si-H2)n complexes. The hydrogen content in the films was found < 7 at. % over the entire range of studied Ar flow rate. The band gap of nc-Si:H films was found to be higher than hydrogenated amorphous silicon (a-Si:H) films (> 2 eV). The nc-Si:H films with dark conductivity 1.3x10-7 S/cm having deposition rate as high as 2.5 Å/s and of crystalline fraction 98 % have been obtained.
Composites of Bromobenzenethiol Functionalized Gold Nanoparticles and the Fluorescent Poly(Phenylene Ethynylene) pPET3OC12-sqS for Optical Biosensors
Authors: Ramos J.C. , Ledezma A. , Moggio Ivana , Arias Eduardo , Vazquez R.A. , Martínez Carlos A. , Torres J.R. , Ziolo Ronald F. , García Perla E. , Sepulveda S. , José-Yacamán Miguel , Olivas A.
Published: March 2009

Bromobenzenethiol passivated gold nanoparticles were mixed with a poly(phenylene ethynylene) bearing thioester flexible sequences in order to obtain a fluorescent composite for optical biosensors. The particles and the composite were characterized by 1H, 13C NMR, UV-Vis and fluorescence spectroscopy, TEM and STEM. The particles are homogeneously dispersed in the polymer matrix as observed by electron microscopy. The NMR spectra suggest that the gold particles and the poly(phenylene ethynylene) are probably interacting through the sulfur atoms of the –C(O)S- and –CH2-S-CH2- moieties of the flexible sequences of the polymer as well as through  interactions between the aromatic ring of 4-bromobenzenthiol and the conjugated backbone of pPET3OC12-sqS. The quantum yield of the composite both in solution and in solid state films is slightly lower than that of pPET3OC12-sqS because of the quenching effect of gold. Nonetheless, a change of the fluorescence intensity of the composite films can be detected as a consequence of the contact with microorganisms. Preliminary microbiological assays indicate an antimicrobial effect of the composite film with the E. coli bacteria.
Synthesis and Characterization of Polyaniline -Crooked Gold Nanocomposite with Reduced Conductivity
Authors: Hawaldar Ranjit R. , Kulkarni M. , Jadkar Sandesh R. , Pal Umapada , Amalnerkar Dinesh
Published: March 2009

Conducting Polyaniline (Pani)-crooked Gold nanocomposites were synthesized by in situ chemo-oxidative polymerization of aniline with previously made crooked gold nanoparticles by using ammonium per oxidisulphate as oxidizing agent and p-toluene sulphonic acid (p-TSA) as dopant. The formation of nano gold was established by UV-visible spectroscopy with a SPR peak at 512 nm and crooked morphology was confirmed by TEM. Spectroscopic analysis confirmed the formation of the conducting emeraldine salt phase of the polymer. Due to clustering of composite nanoparticles, the polymer composite formed one-dimensional rod-like morphologies. Thermogravimetric analysis revealed a typical three-step decomposition pattern pertaining to polyaniline emeraldine salt. The conductivity of the nanocomposite was found to be lower (2.47 S/cm) than the virgin p-TSA doped polyaniline (5.55 S/cm).
Size-Dependent Interdiffusion in Nanomaterials
Authors: Paritskaya Lyudmila N. , Kaganovsky Yuri S. , Bogdanov V.V.
Published: March 2009

The phenomenon of low-temperature homogenization (LTH) during interdiffusion is studied under condition a t Dv £ 2 / 1 ) ( (Dv is the bulk diffusion coefficient, a is the lattice parameter) using nano-objects of binary Cu-Ni and Cr-Ni systems compacted from nano-powders and produced by mechanical alloying. Two stages of LTH were detected: at the first stage (t £ 103 s) the volume fraction of solution rapidly grows; at the second stage (t > 103 s) the volume fraction of solutions grows slowly with practically constant average solution concentration. The first stage of LTH correlates with active grain growth caused by small size (l) of structural element and nonequilibrium structure of nano-objects. Obtained results are analyzed theoretically in terms of interdiffusion along migrating GBs due to grain growth at the first stage and DIGM mechanism at the second stage. It is shown that the GB concentration distribution during interdiffusion along migrating GBs and the kinetics of LTH depend on a parameter l/l where 2 / 1 ) / ( b b V sD d l= is the
characteristic diffusion length. The mechanisms and criteria of LTH are proposed.
The Structure of Nanocrystalline Stainless Steel Powders Obtained by Ball Milling and Duplex Stainless Steel Formed by Their Sintering
Authors: Szymańska Agnieszka , Sikorski Krzysztof , Kazior Jan
Published: March 2009

The article illustrates the influence of ball milling of the 316L and 434L stainless steel
powders as well as their mixture (50 wt. % of 434L + 50 wt. % of 316L) on their structure. Medium size of the grains (about 30 nm) was obtained after 110 hours of milling. The powders that obtained were pressed isostatically and sintered by impulse plasma method in vacuum. The samples were then characterized using an optical microscope equipped with a computer image analyzer, scanning electron microscope and X-ray diffractometer.
Novel Ceramic-Metal Composites with Metal Phase from Micro to Nanosize
Authors: Konopka K.
Published: March 2009

The present paper is focused on ceramic–metal composites obtained via different
technologies which leads to different microstructures in terms of size and distribution of metal phase. Composites analysed in paper were produced by the following methods:(a) infiltration of porous ceramics by metal, (b) consolidation under high pressure and (c) sintering of ceramic powder coated by metal. Their microstructures were investigated by scanning and transmission electron microscopy methods. The three methods of composite fabrication employed in the present study result in specific spatial distribution and dispersion of metal phase. Presureless infiltration of porous ceramics by liquid metal is driven by capillary force and make it possible to produce microstructure with percolation of metal phase in ceramic matrix. The volume fraction of metal phase in this case depends on the size
of pores. The size of pores influence also the kinetics and extent of infiltration. Ceramic preforms with small size of pore are not fully infiltrated. This method is useful for composite with size of metal phase in the range of micrometers. Hot pressing under high pressure produces microstructures of composites with metal phase grain size in the range from nano to micrometers. Moreover, it allows to achieve the nanometric size of ceramic grains. In the case of ceramic powders covered by metal, compression and hot pressing preserves nanometric size of metal. The grain growth of ceramic grains is suppressed.
Al2O3-Fe Functionally Graded Materials Fabricated under Magnetic Field
Authors: Oziębło A. , Konopka K. , Bobryk E. , Szafran Mikolaj , Kurzydlowski Krzysztof Jan
Published: March 2009

This paper describes technology, which can be used to obtain ceramic-metal composites with a gradient of metal particles concentration. Graded composites, have been obtained by slip casting. The gradient of iron concentration was induced by magnetic field. Microstructures of the specimens have been investigated using a light and scanning electron microscopy. Quantitative analysis of microstructures has been carried out with the help of image analyzer. The obtained results prove the possibility to produce Al2O3-Fe functionally graded materials under the magnetic field.
Evaluation of Megasonic Cleaning for Sub-90nm Technologies
Authors: Vereecke Guy , Holsteyns Frank , Arnauts Sophia , Beckx S. , Jaenen P. , Kenis Karine , Lismont M. , Lux Marcel , Vos Rita , Snow James , Mertens Paul W.
Published: March 2009

Cleaning of nanoparticles (< 50nm ) is becoming a major challenge in semiconductor manufacturing and the future use of traditional methods, such as megasonic cleaning, is questioned. In this paper the capability of megasonic cleaning to remove nanoparticles without inflicting damage to fragile structures is investigated. The role of dissolved gas in cleaning efficiency indicates that cavitation is the main cleaning mechanism. Consequently gas mass-balance analyses
are needed to optimize the performance of cleaning tools. When gas is dissolved in the cleaning present tools can remove nanoparticles down to about 30 nm using dilute chemistries at low temperature. Ultimate performance is limited by cleaning uniformity, which depends on tool design and operation. However no tool reached the target of high particle removal efficiency andlow damage. Significantly lower damage could only be obtained by decreasing the power, at the cost of a lower cleaning efficiency for nanoparticles. The development of damage-free megasonic is
discussed.
Investigation of Dissolution and Electrodeposition of Copper in Concentrated and Diluted Oxalic Acid Media in Post-CMP Cleaning
Authors: Gabrielli C. , Mace C. , Matha J. , Mège S. , Ostermann E. , Perrot H.
Published: March 2009

In the microelectronic industry using the damascene process, dendritic growth is observed on some parts of the circuits in critical conditions during the post-CMP cleaning step. To understand the electrochemical mechanism leading to this parasitic phenomenon copper behaviour in oxalic acid media was investigated by impedance measurement in both cathodic and anodic potential range and the dendritic growth conditions were studied.. Copper-oxalate complexes in the solution are taken into account.
UV Activated Surface Preparation of Silicon for High-k Dielectric Deposition
Authors: Finstad Casey C. , Muscat Anthony
Published: March 2009

High-k gate materials, such as HfO2, are unstable on silicon and form low permittivity interfacial oxides when heated. A single layer of silicon nitride grown prior to gate dielectric deposition could serve as a diffusion barrier to prevent oxide formation. A monolayer film of surface amine groups will be chemically similar to surface hydroxyl groups, and could also serve as a seed layer to promote the nucleation of a high-k film. The deposition of amines (≡Si-NH2 or ≡Si-NH-Si≡) on chlorine and hydrogen terminated Si(100) at low temperature (<100°C) was investigated using x-ray photoelectron spectroscopy (XPS). UV-Cl2 exposures (0.1-10 Torr Cl2 at 25-150°C, 10-600 s, 1000 W Xe lamp) were used to terminate Si(100) with Cl atoms. Exposure to NH3 (0.1-1000 Torr, 75°C, 5-60 min) replaced Cl atoms with up to 0.3 ML of amine groups, as measured by XPS. Cl atoms served as reactive leaving groups, lowering the overall activation energy barrier for nitridation. Alternatively, UV photons with energy greater than 5.7 eV were used to photodissociate NH3 molecules, yielding NH2 photofragments that reacted with the H-terminated Si(100) surface. At a UV photon flux of 19 mW/cm2, the N coverage increased with time and saturated at ~1 ML. Significant oxygen was observed on the surface due to H2O contamination in the source gas.
Texture Evolution In Fe-1%Si as a Function of High Magnetic Field
Authors: Bennett Tricia A. , Jaramillo R.A. , Laughlin David E. , Wilgen J.B. , Kisner R. , Mackiewicz-Ludtka G. , Ludtka G.M. , Rollett Anthony D. , Kalu Peter N.
Published: March 2009

The effect of a 1.5T, 15T and 30T magnetic field on texture evolution in Fe-1%Si was investigated by annealing samples for 1 hour at 787°C, (27° above the Curie temperature, Tc = 760°C). The intensity of the Goss texture component increased with increasing field strength accompanied by a drastic increase in grain size.
Influence of Starting Textures on the Development of Texture and Microstructure during Large Strain Hot Rolling of Pure Magnesium
Authors: Al-Samman Talal , Gottstein Günter
Published: March 2009

The plastic behaviour of hexagonal metals such as magnesium is very anisotropic and substantially affected by crystallographic texture. In this work, samples of pure magnesium with different starting textures were hot rolled at 400°C in one rolling pass to different final thicknesses of 5%, 10%, 30%, 50%, 70%, 90%. The microstructure and macrotexture evolution were examined by optical microscopy (OM) and X-ray diffraction, respectively. Further, microtexture analysis was done by EBSD. Texture modelling with LAPP using an FC Taylor model, based on the expected active slip and twinning modes was performed. The results were compared with the measured textures.
Simulation of Deformation Texture Evolution Using an Intermediate Model
Authors: Ahzi Saïd , M'Guil S.
Published: March 2009

The aim of this work is to propose the use of an intermediate model for large viscoplastic deformations that could predict the texture transition and stress-strain behavior in a range that spans from the upper bound (Taylor) to the lower bound (Sachs) estimates. In this model, we introduced a single parameter as a weight function to formulate the intermediate model which combines the Taylor and Sachs estimates. For the applications, we focus on the three main tests: plane strain compression, uniaxial tension and compression. An FCC polycristal represented by 100 crystals with an initially random orientation is used. The results for texture evolution show that a transition between the copper and brass type textures can be obtained by the proposed intermediate model.
Texture Development in Nd-Fe-V and Nd-Fe-B Alloys by Hot Forging in View of Improving Permanent Magnet Properties
Authors: Rivoirard Sophie , Popa I. , Chateigner Daniel , Ouladdiaf B. , de Rango Patricia , Fruchart Daniel
Published: March 2009

A high speed hot forging process was applied to Nd-Fe-B and Nd-Fe-V as cast alloys in order to develop both the microstructure and the crystallographic texture appropriate for permanent anisotropic magnet properties. Neutron diffraction texture analyses are used to demonstrate the effect of the hot forging process on both kind of alloys. Microstructural changes are an important feature on forging in both cases. Coercivity is developed in the Nd-Fe-B alloy mainly from grain size reduction and disappearance of free iron. Stabilisation of the Nd(Fe,V)12 hard magnetic phase is achieved from the iron and Nd-rich microstructure of the starting Nd-Fe-V material. A comparison of the crystallographic textures of Nd2Fe14B and Nd(Fe,V)12 phases is done to account for the development of extrinsic magnetic anisotropy. In both cases, a nearly fibre texture is obtained in correlation with the symmetry of the deformation. However, the orientations are quite different in both alloys and the consequences on the magnetic properties are evidenced.
Oblique Cube Texture Formation in High Purity Aluminum during Equal Channel Angular Pressing
Authors: Skrotzki Werner , Scheerbaum N. , Oertel C.G. , Brokmeier Heinz Günter , Suwas Satyam , Tóth László S.
Published: March 2009

Aluminum of 5N purity has been deformed at room temperature by equal channel angular pressing using three passes of route A. The microstructure and texture have been investigated by electron back-scattering and neutron diffraction. The microstructure from the first pass on is totally dynamically recrystallized. The recrystallization texture consists of an oblique cube component. The oblate grains and the cube texture are anticlockwise rotated about the transverse direction. The inclination with respect to the extrusion direction depends on the distance from the top of the extruded bar and changes from pass to pass. The mechanism of ormation of the recrystallization microstructure and texture is discussed.
Advances in Automatic TEM Based Orientation Mapping
Authors: Fundenberger Jean-Jacques , Morawiec Adam , Bouzy Emmanuel
Published: March 2009

The paper is an account of TEM based automatic orientation mapping summarizing more than two years of using the system. Following a brief introduction of the system elements, some representative applications are described. We focus on the characterization of fine-grain materials, mapping of low symmetry materials (metastable chromium carbide) and semi-automatic analysis of misorientations in a fully lamellar polycrystalline (g+a2) TiAl alloy. Moreover, the current state of the TEM based system is discussed and compared to EBSD systems. In particular, the issues of spatial resolution, accuracy, map acquisition time, reliability are considered.
Simulating the Temper Rolling of Galvanized Steel
Authors: Vincent G. , Counhaye C. , Esling Claude
Published: March 2009

This work deals with early results obtained in numerical simulation of the skin-pass of zinc coated steel sheets. First, the streamline model and its adaptation to the case of the temper rolling of coated steel sheets are detailed. Second, the influence of various parameters of the rolling process on the strain and stress fields in the sheet is numerically calculated.
Aluminum Matrix Texture and Particle Characterization in Al-Al3Ti FGMs Produced by a Centrifugal Solid-Particle Method
Authors: Sequeira P.D. , Watanabe Yoshimi , Rocha L.A.
Published: March 2009

The centrifugal solid-particle method has proved to be effective in producing functionally graded materials (FGMs). In this study, Al-Al3Ti FGMs, were produced by this centrifugal method, from an Al-5 wt % Ti master alloy. Applied centrifugal forces were 30, 60 and 120G (units of gravity). Samples from the outer surface of each specimen were cut and aluminum matrix texture analyzed by Schulz reflection method. Analysis of the resulting pole figures indicates a preferred orientation along the (200) plane for the aluminum matrix crystals. Furthermore, increasing the applied centrifugal force enhances the orientation effect. Al3Ti platelet orientation and area fraction at the samples’ outer surface along three observation planes were also measured. The Al3Ti platelets in the outer region are orientated perpendicular to the centrifugal force direction along two of the observed planes, also an increase in centrifugal force leads to an increase in orientation in those two planes. The intermetallic particle volume fraction also increases with higher applied centrifugal force, although not significantly. A correlation appears to exist between particle orientation and the preferred orientation of the matrix.
Texture Analysis of CVD Free-Standing Diamond Films
Authors: Chen Leng , Feng H.P. , Lu Fan Xiu
Published: March 2009

The crystallographic textures of the free-standing diamond films which were synthesized by the chemical vapor deposition (CVD) using a CH4/H2/Ar gas mixtures have been investigated. Texture components of the diamond films are analyzed with pole figures and orientation distribution function (ODF). The surface morphology of the diamond films grown at different substrate temperatures as well as different gas concentrations is observed with scanning electron microscopy (SEM). The experimental results indicate that the intensity of {110} fibre texture becomes much higher with the increase of the substrate temperature. It is considered that the higher multiplicity of <110> crystallographic direction in diamond octahedron leads to the higher appearance possibility of {110} fibre texture and the final texture components of the diamond films depend upon the CVD deposition parameters.
Local Orientation Measurements in 3D
Authors: Juul Jensen Dorte
Published: March 2009

The 3 Dimensional X-Ray Diffraction (3DXRD) method is presented and its potentials illustrated by examples. The 3DXRD method is based on diffraction of high energy X-rays and allows fast and nondestructive 3D characterization of the local distribution of crystallographic orientations in the bulk. The spatial resolution is about 1x5x5 µm but diffraction from microstructural elements as small as 100 nm may be monitored within suitable samples. As examples of the use of the 3DXRD method, it is chosen to present results for complete 3D characterization of grain structures, in-situ “filming” of the growth of one interior grain during recrystallization, recrystallization kinetics of individual grains and crystallographic rotations of individual grains during tensile deformation.
EPSILON-MDS – A Neutron Time-of-Flight Diffractometer for Strain Measurements
Authors: Walther Kurt , Frischbutter Alexander , Scheffzük Christian , Korobshenko M. , Levshanovski F. , Kirillov A. , Astachova N. , Mureshkevich S.
Published: March 2009

This paper describes the modernized diffractometer EPSILON-MDS for strain measurements of geological samples by means of neutron diffraction with the time-of-flight method. The diffractometer is characterized by a long flight path in order to get a good spectral resolution and by a multi-detector system for efficient data acquisition.
Distribution of Dislocation Density in Tubes from Zr-Based Alloys by X-Ray Data
Authors: Isaenkova Margarita , Perlovich Yuriy
Published: March 2009

As applied to tubes from Zr-based alloys, the X-ray method was developed to determine the dislocation density distribution in a-Zr depending on the orientation of Burgers vector. The method consists in registration of X-ray line profiles by each successive position of the sample in the course of diffractometric texture measurement using reflections of two orders, the following determination of coherent domain size and lattice distortion by means of the Warren-Averbach method for each orientation of reflecting planes, separate calculation of the density of c- and a-dislocations with all possible orientations of Burgers vector and presentation of results in generalized pole figures. Obtained data testify that the dislocation density varies within very wide intervals of several orders of magnitude depending on the grain orientation both in as-rolled and annealed tubes. Features of the constructed dislocation distributions are closely related to the crystallographic texture of studied tubes.
Additional Absorption in the Multiply Scattering Absorbing Media
Authors: Yashchuk Vasil P. , Tikhonov E. , Prygodjuk O. , Levandovska O. , Zhuravsky M.
Published: March 2009

Numeric simulation of light passing through the scattering medium by the Monte-Carlo method was carried out. The influence of multiple scattering on the light beam attenuation in an absorbing media was investigated. The additional absorption appearance was shown to be initiated by multiple scattering. The experimental evidence for this absorption is abrupt increasing of beam attenuation at high particle concentrations. The behaviour of the additional absorption was investigated. The results of numeric calculation are in good agreement with experimental results.
Review on the Production and Synthesis of Nanosized SnO2
Authors: Papargyri S. , Tsipas D.N. , Papargyris D.A. , Botis A.I. , Papargyris Athanasios D.
Published: March 2009

Tin dioxide is a wide band semiconductor, with interesting chemical physical and mechanical properties, used in a variety of industrial, domestic, medical and agricultural applications, including gas detectors, transparent conductors, solar cells, anti-static films, nanoelectronic devices etc. The variety of nanosized SnO2 production methods in the form of powders or layers (e.g. solid state, sol-gel, sputtering, laser ablation, template, solution precipitation, precursor oxidation, CVD, PVD, etc) are discussed.
Natural Opal as a Model System for Studying the Process of Biomineralization
Authors: Pramatarova Lilyana , Pecheva Emilia , Presker R. , Schwarz U. , Kniep R.
Published: March 2009

Opal is a natural nanostructure model. It possesses nanosized close packed silica spheres and a regular sublattice of voids, filled with molecular water and accessible for filling by other substances. Using natural opal as a substrate, no complimentary technique is needed to produce a patterned surface as it is present naturally. Thus, the possession of nano-dimensions for efficient influencing of different biological events can be used in the laboratory and biologically integrated multifunctional devices (biomaterials, sensors) could be created. Additionally, biomineralization mechanisms may be studied using model systems. The main purpose of the work is to use nanostructured or other functionalized materials as models to contribute to the study of biomineralization. Particularly this paper reports on the ability of natural opal from Bulgaria's Eastern Rhodopes mountain to induce the deposition of a surface layer of calcium phosphate from simulated body fluid. Raman, infrared spectroscopy and XRD were used to show that opal consists of two main phases: microcrystalline quartz and cristobalite and that the observed with optical microscopy layer deposited from the simulated body fluid on both phases was calcium phosphate.
Formation and Characteristics of the Low Dielectric Carbon Doped Silicon Oxide Thin Film Deposited by MTMS/O2 – ICPCVD
Authors: Yang Chang Sil , Lee Heon Ju , Choi Chi Kyu
Published: March 2009

Carbon doped silicon oxide (SiOC(-H)) films with low dielectric constant were deposited on a p-type Si(100) substrate using inductively coupled plasma chemical vapor deposition with a methyltrimethoxysilane (MTMS : CH3Si(OCH3)3) precursor and oxygen gases. The dielectric constant of the SiOC(-H) composite film depends on the relative carbon concentration and the content of the ring link mode in SiOC(-H) bonding structure. The elastic modulus and the dielectric constant decreased by the annealing process. The lowest dielectric constant of an annealed film at 400 °C was about 2.25, which was deposited with [MTMS/(MTMS+O2)]×100 flow ratio of 100%.
Radiation Production Using Femtosecond Electron Bunches
Authors: Thongbai C. , Jinamoon V. , Kangrang N. , Kusoljariyakul K. , Rimjaem S. , Saisut J. , Vilaithong Thiraphat , Rhodes M.W. , Wichaisirimongkol P. , Chumphongphan S.
Published: March 2009

Femtosecond electron bunches can be generated from a system consisting of an RF gun with a thermionic cathode, an alpha magnet, and a linear accelerator and can be used to produce femtosecond (fs) electromagnetic radiation pulses. At the Fast Neutron Research Facility (FNRF), Thailand, we are especially interested in production in Far-infrared (FIR) and x-radiation. In the far-infrared, radiation is emitted coherently for wavelengths which are longer than the electron bunch length, yielding intense radiation. Although, the x-rays emitted are incoherent, its femtosecond time scale is crucial for development of a femtosecond x-ray source.
Structural and Conductive Changes of Alumina Ceramics and Silicon Crystal Implanted with High-Flux Ti Ion
Authors: Wu Xue Mei , Li D.X. , Yu M. , Zhang Ji Zhong
Published: March 2009

95% Al2O3 ceramics and Si <100> crystal were implanted by Ti ion in a MEVVA implanter. The influence of implantation parameters was studied by varying ion fluence. The samples were implanted by 80 keV Ti ion with fluences from 1 x1015 to 1 x 1018 ions/cm2, respectively. The samples were investigated by SEM, SAM, and four-probe measurement. Differentmorphologies were observed on the surfaces of the samples due to irradiation damage, and clearly related to implantation parameters. XRD spectra confirm formation of titanium silicides on the surfaces of Si samples with ion fluences equal to or high than 1x1015 ions/cm2. The experimental results suggest that it is possible to synthesise titanium silicides by using a MEVVA implanter.
Atmospheric Pressure Plasma Jets for 2D and 3D Materials Processing
Authors: Kędzierski Jacek , Engemann Jürgen , Teschke Markus , Korzec Dariusz
Published: March 2009

A novel atmospheric pressure plasma jet with a cylindrical symmetry i.e. a tubular dielectric barrier and two tubular electrodes was developed at Microstructure Research Center – fmt, Wuppertal, Germany. The jet was investigated by means of ultra fast (down to tens of nanoseconds exposition time) ICCD photography and regular CCD photography. Some spectacular results were achieved and their partial explanation was presented. The jet acts as a “plasma gun” throwing small “plasma bullets” out of its orifice. The most important findings are: (i) the bullet velocity is approximately 3 orders of magnitude larger than the gas flow velocity, and (ii) the jet dynamics is mainly electrical field controlled. A simple model - formation of a jet in air - based on a Helium metastables core can explain qualitatively reasonably well most of our experimental observations. Some variations of the original cylindrical jet geometry were presented and discussed: microjet and fmt Plasma-Pen, single tube multijet, tube-in-tube single and multijet systems (so-called “Wuppertal-Approach”).
Thermal Stability of Nanoscale Multilayered ZrAlN/ZrB2 Coatings
Authors: Li D.J. , Zhang J.J. , Wang Ming Xia
Published: March 2009

Multilayered ZrAlN/ZrB2 coatings were synthesized using a multi-cathode dc magnetron sputtering technique. Effects of substrate bias and N2 gas partial pressure on structural, mechanical properties, as well as thermal stability were investigated. Low bias was beneficial to synthesis of nanolayers with weak internal stress. The nanolayers deposited at lower N2 partial pressure and substrate bias exhibited good high-temperature stability in the crystalline and layer structure, and hardness values were increased significantly after high-temperature annealing.