bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Chemical Composition on Microstructure and Transformation Behavior of NiTi Shape Memory Alloy Prepared by Vacuum Arc Melting
Authors: Bornapour Mandana , Motemanni Y. , Nili-Ahmadabadi Mahmoud , Raygan S.
Published: March 2009

NiTi shape memory alloys are a group of materials which have a lot of applications
especially in aerospace industries and medical equipments because of their excellent properties.
Shape memory effect (SME), pseudo-elasticity (PE), high corrosion resistance and biocompatibility
is special properties of these alloys which lead to their extensive applications. The superior behavior
of NiTi alloy is due to thermoelastic martensitic phase transformation. In the present paper, two NiTi
shape memory alloys were prepared by non-consumable vacuum arc melting technique in copper
water cooled crucible. One of them had commercial elements and the other had high purity elements.
Metallographic investigation, chemical analysis, XRD and DSC were carried out on two alloys.
Metallographic observation and XRD shows that structure at ambient temperature consists of
austenite phase besides Ti2Ni, Ni3Ti intermetallic compounds and martensite phase. Transformation
investigation determines that the impurity such as iron in commercial alloy causes two stage phase
transformation B2→R→B19′.
Effects of Nano-Sized BN Doping on the Phase Formation, Tc and Critical Current Density of MgB2 Superconductor
Authors: Soltanian S. , Delfany M. , Wang X.L. , Qin M.J. , Liu H.K. , Dou S.X.
Published: March 2009

MgB2 polycrystalline bulk samples with additions of 0, 5, 10 and 20% wt.% nano-sized BN powders were prepared using the reaction in-situ method. All the samples were sintered at 850°C for 1h in Ar. All the samples were characterized by X-ray diffraction, scanning electron microscopy (SEM) and magnetic measurements. The X-ray diffraction patterns show that the BN does not react with Mg and B during the heat treatment and remains as a separate phase. The synthesized materials thus contain two separate BN and MgB2 phases. In addition, the samples contain a small, almost constant amount of MgO. SEM shows that the samples contain MgB2 grains with average grain sizes of about 250 nm. Magnetic measurement results show that the critical current density and irreversibility fields decrease slightly as the BN level increases. The Tc drops slightly from 38.9 to 38.2 K and has a sharp transition with a transition width of less than 1 K. The field dependence of Jc for all the samples is also presented.
Photoluminescence and Raman Scattering Correlated Study of Boron-Doped Silicon Nanowires
Authors: Zeng X.B. , Liao X.B. , Dai S.T. , Wang B. , Xu Y.Y. , Xiang X.B. , Hu Z.H. , Diao H.W. , Kong G.L.
Published: March 2009

Boron-doped (B-doped) silicon nanowires (SiNWS) have been prepared and characterized by Raman scattering and photoluminescence (PL). B-doped SiNWS were grown by plasma enhanced chemical vapor deposition (PECVD), using diborane (B2H6) as the dopant gas. Raman spectra show a band at 480cm-1,which is attributed to amorphous silicon. Photoluminescence at room temperature exhibits three distinct emission peaks at 1.34ev,1.42ev,1.47ev. Possible reason for these is suggested. PACS: 36.40._c; 81.15.Gh; 81.20._n
Effect of Presence of Nano-Size Alumina Particles on the Properties of Elemental Magnesium
Authors: Zhong X.L. , Gupta Manoj
Published: March 2009

In present study, elemental magnesium was reinforced with nano-size alumina
particles (50-nm). The composite samples were synthesized using the technique of powder metallurgy and the effect of extrusion temperature and sintering on the end properties was particularly investigated. The results of microstructural characterization studies confirmed the presence and reasonably uniform distribution of alumina particles. Results obtained from extruded unsintered samples revealed that the hardness and dimensional stability of magnesium increases with an increasing presence of alumina particles while the 0.2%YS, UTS and ductility
deteriorated. Results further revealed that including sintering step and extruding at higher temperature lead to an increase in dimensional stability, hardness, 0.2%YS, UTS and ductility for an alumina content as low as one percent by weight.
Microstructural Evolution and Nanocrystalline Formation Kinetics in FeCo Based Alloys During Mechanical Alloying
Authors: Li H.F. , Ramanujan R.V.
Published: March 2009

Mechanical alloying (MA) is a widely used processing technique to prepare metastable or nanophase materials in a cost effective fashion. In this study, mechanically alloying FeCo based nanomagnetic alloys was included. Scanning electron microscope (SEM), X-ray diffractometer (XRD), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) were used to characterize the as milled powders. The effect of additional elements P and B on the powder size, microstructures and magnetic properties is discussed. It showed that the addition of P and B could reduce the powder size more effectively. The addition of elements P and B during MA of FeCo magnetic alloy also led to the formation of spherical nanocrystallines instead of banded microstructures in MA FeCo without these additions.
Nanocrystallization Behavior of Fe40Ni38B18Mo4 Soft Magnetic Alloy
Authors: Du S.W. , Ramanujan R.V.
Published: March 2009

The Herzer model suggests that superior magnetic properties can be observed in magnetic alloys provided a suitable microstructure consisting of soft magnetic nanometre size precipitates separated by nanometre size distances is obtained. In order to explore new magnetic alloy compositions which can satisfy the Herzer model, we studied selected alloys in which we wished to obtain suitable microstructures, one such alloy has the composition Fe40Ni38B18Mo4. This alloy is amorphous as received, the heat treatment schedule required to obtain nanoprecipitates was designed based on DSC, resistivity and x-ray results. Heat treatment at temperatures between 420 0C and 500 0C and different heat times was carried out on the amorphous ribbon. Transmission Electron Microscopy (TEM) results of the early stage of crystallization behavior showed that soft magnetic precipitates of nano-size were indeed observed within the amorphous matrix. The crystal structure, composition analysis and thermal stability of the precipitates were studied by XRD, EDS and TEM. These results will be presented and the implication of these results to the production of new soft magnetic alloys will be emphasized.
Thermo-Mechanical Modeling and Analysis of Equal Channel Angular Pressing
Authors: Pei Qing Xiang , Hu B.H. , Lu C.
Published: March 2009

Thermo-mechanical finite element analysis was carried out to study the deformation behavior and temperature distribution during equal channel angular pressing (ECAP). The material model used is the Johnson-Cook constitution model that can consider the multiplication effect of strain, strain rate, and temperature on the flow stress. The effects of pressing speed, pressing temperature, workpiece material and die geometry on the temperature rise and flow behavior during ECAP process were investigated. The simulated temperature rise due to deformation heating was compared with published experimental results and a good agreement was obtained. Among the various die geometries studied, the two-turn die with 0° round corner generates the highest and most uniform plastic strain in the workpiece.
Wear of Mg-5%Al-5%Nd Alloy with Nanocrystalline Grain Size
Authors: Lim C.Y.H. , Lu L.
Published: March 2009

This paper explores the wear characteristics of nanocrystalline Mg-5%Al-5%Nd,
synthesized by mechanical alloying. Pin-on-disc unlubricated sliding wear tests were conducted against a hardened tool-steel counterface under loads of 10 and 30 N, and within a velocity range of 0.2-5.0 m/s. Despite its appreciably superior mechanical properties, the nanostructured alloy did not exhibit the expected improvement in wear resistance when compared to its conventional microngrain-
sized counterpart; in fact, the former performed worse when testing conditions became more severe. Scanning electron microscopy (SEM) suggested that extensive delamination in the nanocrystalline alloy was the primary reason for its high wear rates. This wear mechanism was promoted by the presence of MgxNd dispersiods, which were found only within the nanocrystalline material. These compounds likely resulted from the long duration (20 hrs) of ball-milling, which
was the mechanical alloying technique employed to reduce the grain size of the final alloy.
Influence of the Gas Phase Composition on Nanocrystalline Diamond Films Prepared by MWCVD
Authors: Popov Cyril , Jelínek Miroslav , Boycheva S. , Vorlícek V. , Kulisch Wilhelm
Published: March 2009

Nanocrystalline diamond (NCD) films have been prepared by microwave plasma chemical vapor deposition (MWCVD) from methane/nitrogen mixtures, and the influence of the gas phase composition on the basic properties of the films (composition, morphology, topography, crystallinity and bonding structure) was investigated.
Investigation on Field Electron Emission from Carbon Nanotubes on Nanocrystalline Diamond Films
Authors: Liao K.J. , Wang W.L. , Cai C. , Lu J.W. , Hu C.G.
Published: March 2009

The electron field emission from carbon nanotubes on nanocrystalline diamond films was investigated. Carbon nanotubes and nano-diamond films were deposited on Si substrates by hot filament chemical vapor deposition. The experimental results showed that the carbon nanotubes on nanostructured films exhibited a lower value of the turn-on electric field than those of carbon nanotubes and nano-diamond. It was found that the turn-on field of nanotubes on nano-diamond was about 0.9V/μm, which was lower than those of carbon nanotubes and nano-diamond.
Magnetism and Radio-Frequency Dynamics in Nanocomposite Materials
Authors: Srikanth H. , Poddar P.
Published: March 2009

Nanocomposites hold tremendous potential as ‘designer’ materials with multifunctional, tunable physical properties. We have synthesized and studied two classes of nanocomposite systems –(a) Magnetorhelogical (MR) fluids with uniformly dispersed Fe nanoparticles and (b) Polypyrrole doped with soft ferrite nanoparticles. Static and dynamic magnetic measurements show a variety of phenomena ranging from superparamagnetism to collective spin-flip transitions. A resonant RF method has been used to map the switching and anisotropy fields. Our studies indicate that the rich cooperative magnetism in these systems is governed not only by the particle size distribution but also by the matrix-mediated interactions.
Nanoindentation Study of Polymer Based Nanocomposites
Authors: Nai M.H. , Lim Chwee Teck , Zeng K.Y. , Tan Vincent B.C.
Published: March 2009

Nanoindentation is a useful technique to measure hardness as well as elastic and timedependent plastic properties of materials with nanometer resolution. The measurement of elastic modulus of polymeric materials remains challenging due to their viscoelastic behavior. Clay reinforced nylon6 nanocomposites are found to have great improvement in the elastic modulus and tensile strength due to exfoliated hybrid structure. However, its mechanical properties have not been well investigated. In the present study, hardness and elastic modulus of nylon6-5wt%clay nanocomposites were investigated using nanoindentation. Creep effects of the nanocomposites on the unloading stiffness, which directly relates to the elastic modulus, were studied under various unloading rates and holding periods. It was found that the elastic modulus and hardness of nylon6-5wt%clay nanocomposites increased by 58% and 80%, respectively, as compared to pure nylon6. Experimental results for both polycarbonate and nylon6-5wt%clay nanocomposites showed that loading rate had no significant effects on the unloading stiffness. However, stiffness decreased to more consistent values after longer holding periods (more than 30 sec) and at faster unloading rates. The results indicated that creep behavior of the polymers affects the measurement of the unloading stiffness and may possibly overestimate the elastic modulus. Errors in the stiffness measurements from nanoindentation could be minimized with appropriate loading, unloading and holding conditions.
Nonlinear Optical Behavior of Transparent Nanohybrids of Nanocrystalline TiO2 in Poly(methyl methacrylate) Prepared by In Situ Sol-Gel Polymerization Technique
Authors: Yuwono A.H. , Xue J.M. , Wang J. , Elim H.I. , Ji Wei , Li Yuan Yuan , White T.J.
Published: March 2009

Nanohybrid thin films consisting of nanocrystalline TiO2 particles in poly(methyl methacrylate)(PMMA) were successfully synthesized by in-situ sol-gel and polymerization assisted by spin coating. Using titanium isoproproxide (Ti-iP), methyl methacrylate (MMA) and 3-(trimethoxysily)propyl methacrylate (MSMA) as the starting materials, nanohybrids containing up to 60% Ti-iP in PMMA were realized. The resulting nanohybrid thin films coated on quartz substrates are optically transparent and demonstrate nonlinear optical behaviour, where their nonlinear absorption increases with the loading of Ti-iP in PMMA, as confirmed by Z-scan measurements. Using pump-probe technique, these thin films are shown to exhibit an ultrafast relaxation time of ~1.5 picosecond.
Modelling of Negative Poisson's Ratio Nanomaterials: Deformation Mechanisms, Structure-Property Relationships and Applications
Authors: Alderson A. , Alderson K.L. , Evans K.E. , Grima J.N. , Williams M.S.
Published: March 2009

Analytical and Molecular Mechanics methods have been used to study the deformation mechanisms acting at the molecular level in the auxetic polymorph of crystalline silica (a-cristobalite). The analytical models indicate that a-cristobalite deforms by concurrent tetrahedral dilation and cooperative rotation when stretched along the x3 axis, and that a second phase is predicted to exist for this loading scenario, having a geometry similar to that of ‘idealised’ b-cristobalite. This is supported by preliminary Molecular Mechanics simulations, which also indicate
that the cooperative rotation predicted for loading along x3 is not sufficient to describe the deformation mechanism for loading along x1. A negative hydrostatic pressure offset is observed to lead to a change in the sign of the predicted Poisson’s ratio from positive to negative, leading to improved agreement of the Molecular Mechanics model with experiment.
Nanocrystalline W-Doped SrBi2Ta2O9 of Layered Perovskite Structure Derived from Mechanical Activation
Authors: Toh W.S. , Zhou Z.H. , Xue J.M. , Wang J. , Barber Zoe H. , Evetts J.E.
Published: March 2009

To study the effects of doping the layered perovskite SrBi2Ta2O9 with an appropriate amount of tungsten, both undoped and W-doped SrBi2Ta2O9 (SBT) of nanocrystallinity were synthesized by mechanical activation of constituent oxides of strontium oxide, bismuth oxide, tantalum oxide and tungsten oxide at room temperature. A nanocrystalline single perovskite phase was observed in SrBi2(Ta1-xWx)2O9 with up to x=0.1. SrBi2(Ta0.9W0.1)2O9 shows a higher Curie
temperature than that of undoped SBT, although it exhibits a very similar layered perovskite structure. The ferroelectric and impedance behaviors of SrBi2 (Ta0.9W0.1)2O9 were studied over a range of test temperatures and frequencies, in order to understand the effects of W-doping in SBT, given that W exhibits a similar ionic size to Ta but with a variable valence.
Nanocrystalline Zirconium Oxide Thin Films Prepared by Filtered Cathodic Vacuum Arc
Authors: Zhao Z.W. , Tay B.K. , Yu G.Q. , Lau S.P.
Published: March 2009

Zirconium oxide thin films were deposited at room temperature by using off-plane filtered cathodic vacuum arc (FCVA). Deposition rate, film structure, compositional analysis and optical properties are studied as a function of working pressure. Deposition rate as high as 53 nm/min could be achieved. As increasing working pressure, the film structure changes from Zr-O solid solution, to monoclinic structure with preferred orientation and finally to randomly oriented nanocrystalline structure. The averaged crystal size increases with working pressure and is less than 15 nm. The ratio of O/Zr increases with working pressure as well as transmittance and good stoichiometric film could be achieved with high transmittance of 91% at high working pressure.
Research of Nanostructure of Bivalva Shell
Authors: Chen Bin , Fan Jing Hong , Wang J. , Peng X. , Wu Xiao Lin
Published: March 2009

Molluscan shells is a natural ceramic composite with excellent fracture strength and
fracture toughness, which are attributed to their unique microstructures. Sanning electron microscope (SEM) observation on Bivalva shell showed that the shell consists of laminated aragonite and organic layers. These aragonite and organic layers are provided with the scale and characteristics of nanometer. The effect and function of these nanometer structures were analyzed based on Griffith criterion and energy-dissipation idea. The higher fracture strength and fracture roughness of bionanocomposite-molluscan shell were well explained with nanometer viewpoint.
A Novel Approach to Synthesis of FePt Magnetic Nanoparticles
Authors: Elkins Kevin E. , Chaubey Girija S. , Nandwana Vikas , Liu J.Ping
Published: March 2009

Chemical reduction of ferric acetylacetonate (Fe(acac)3) and platinum acetylacetonate (Pt(acac)2) using polyol as a reducing agent as well as an effective surfactant, has successfully yielded monodisperse FePt nanoparticles with a size of approximately 2 nm. When annealed samples were compared to FePt nanoparticles synthesized using oleic acid and oleylamine as the surfactants under identical conditions, nearly 30% increase in coercivity (Hc) was achieved with the new, simple and economic method.
Molecular Dynamics Simulations of Nanoparticle-Surface Collisions in Crystalline Silicon
Authors: Valentini Paolo , Dumitrica Traian
Published: March 2009

We present a microscopic description for the impacting process of silicon nanospheres onto a silicon substrate. In spite of the relatively low energy regime considered (up to 1 eV/atom), the impacting process exhibits a rich behavior: A rigid Hertzian model is valid for speeds below 500 m/s, while a quasi-ellipsoidal deformation regime emerges at larger speeds. Furthermore, for speeds up to 1000 m/s the particle undergoes a soft landing and creates a long-lived coherent surface phonon. Higher speeds lead to a rapid attenuation of the coherent phonon due to a partial diamond cubic to-tin phase transformation occurring in the particle.
Magnetorheology of Multiwalled Nanotube Dispersions in Mineral Oil
Authors: D'Souza Nandika Anne , Yang Zheng Tao
Published: March 2009

The magnetorheological (MR) effect of multi-walled carbon nanotubes (MWNT) was investigated. Three concentrations of MWNT were dispersed in mineral oil (0.5, 1.5 and 2.53 vol% nanotubes). Rheological investigations were conducted on a magnetorheological cell coupled to a controlled stress rheometer. Oscillatory tests and rotational tests were conducted. A sinuisoidal strain between 0 and 1 with a frequency of 1 Hz was applied and the stress amplitude measured for 0, 171 and 343 kA/m magnetic field strengths. Linear viscoelasticity was determined to exist at strains less than 5%. Dynamic frequency sweeps were conducted at a strain of 1% between 0 and 100 radians/s. A crossover from viscous to elastic behavior was observed for some concentrations. The crossover frequency decreased with field strength as well as with concentration of MWNT. Rotational tests were conducted between shear rates of 0 to 100/s. All dispersions had a zero shear yield stress indicative of Bingham behavior. A magnetosweep was conducted by keeping the strain within the linear viscoelastic region at a frequency of 1 Hz and ramping the magnetic field strength from 0 to 343 kA/m. The results indicate that MWNT show MR behavior.
Non-Linear Optical Effects in Au Nanoparticle-Deposited ZnO Nanocrystalline Films
Authors: Ozga Katarzyna , Kawaharamura Toshiyuki , Umar Akrajas Ali , Oyama Munetaka , Slezak Andrzej , Fujita Shizuo , Kityk Ivan
Published: March 2009

Applying a bicolor coherent treatment of a Nd-YAG laser with wavelength 1.32 μm and
its second harmonic generation, we have investigated photoinduced SHG in Au nanoparticledeposited
ZnO nanocrystallinne (NC) films. We have established that coexistence of the such
crystallites gives substantially better results compared to the pure ZnO NC deposited onto the glass
substrate. It was shown that the value of the second order susceptibility obtained for the large
incident angles of the fundamental and writing beams is equal to about 23 pm/V. The better results
are obtained during the phototreatment at temperatures near the 60 oC for the Au doped samples and
is almost non-sensitive to temperature for the pure samples. The further increase of the temperature
leads to decay of the optical second harmonic generation
Thin Solid Films and Nanomaterials for Solar Energy Conversion and Energy Saving Applications
Authors: Yianoulis P. , Giannouli M.
Published: March 2009

Important new applications are possible today in the fields of energy conversion and
storage by the application of thin and nanostructured solid films on surfaces. These special films, or
multiple films, will be integral parts of the energy systems in the near future for the production of
useful thermal and electrical energy and for energy saving applications, especially in buildings. We
review the research in this direction. As we are facing the threats of insufficient energy supply and
the greenhouse gas emissions from the intense use of fossil sources, we realize that the impacts as
well as the future of the solar energy systems have been greatly underestimated. We review the
work on solar thermal systems and energy saving applications. The efficient use of solar thermal
technologies is very important for the introduction of a sizeable share of environmentally friendly
renewable energy sources. New and nano structured materials along with the design and the
geometry of advanced systems, capable of achieving high temperatures, as well as on integrated
collection and storage systems have been proposed. Recent progress in high-vacuum technology
and new materials had a remarkable effect in thin-film quality and cost. As a result new thermal
absorbers have appeared along with new evaluation methods. We also present work on low-e
coatings and electrochromic thin films that are very important for thermal energy savings in
buildings and increase the efficiency of devices. For the photovoltaic solar energy conversion we
present results on thin film solar cells and the efforts on dye sensitized nanostructured and organic
solar cells.
Nanoscaled Multilayer Thin Films Based on GZO
Authors: Cheng Ching Hsuang , Wu Wan Yu , Ting Jyh Ming
Published: March 2009

Nanoscaled gallium-doped ZnO (GZO) thin films, bi-layer Pt/GZO thin films, and tri-layer
GZO/Pt/GZO thin films were prepared and their characteristics were investigated. These films were
deposited on glass substrates using either rf or dc magnetron sputter deposition. The deposition time
and the target-to-substrate distance were varied to obtain different total film thicknesses and layer
thicknesses. Effects of total film and layer thicknesses on the optical properties and the electrical
properties were studied. Theoretical calculations were performed to discuss effect of the thickness on
the optical transmittance of the GZO film. As-deposited GZO films show high electrical resistivity,
which was greatly reduced by 2 to 3 orders of magnitude due to the introduction of a surface layer of Pt
film. However, the optical transmittance was also reduced. This was improved by using an addition
anti-refractive GZO surface layer on the Pt/GZO. A GZO/Pt/GZO film exhibiting visible light
transmittance greater than 75% and electrical resistivity in the order of 10-4 ohm-cm was obtained.
Development of Radar Absorbing Nano Crystals under Thermal Irradiation
Authors: Sharma Rahul , Agarwala Ramesh Chandra , Agarwala Vijaya
Published: March 2009

Single phase W-type barium hexaferrite nano crystals of radar absorbing material
(RAM) i.e., BaMe2Fe16O27 (Me2+=Fe2+) were synthesized by a modified flux method that combines
the controlled chemical co-precipitation process for nucleation and complete uniform growth during
in-situ annealing with NaCl flux under vacuum furnace. Uniform structure morphological
transformation of nano crystals from spherical to prism faces were noticed after annealing with
increasing temperatures from 200 to 1200 oC for 4 h in vacuum. XRD results showed the single
phase nanocrystals of BaFe18O27 with increasing crystallanity and size from 10 to 90 nm during
annealing. FESEM and TEM were used to investigate the systematic growth processes of various
morphologies of nano crystals. The effect of such systematic morphological transformation of
nanocrystals was observed in dielectric, dynamic magnetic and refection loss (RL) properties in Kuband
(12.4 -18.0 GHz). A significant increment from -15.23 dB to -43.65 dB with wide range of
bandwidth in RL loss is noticed due to the symmetric morphological growth of single phase nano
crystals of RAM during annealing. This process of crystal growth, morphology evolution and RL
enhancement with respect to increasing temperature were also explained in terms of ostwald
ripening and quantum size effect.
Silver Core - Silver Oxide Shell Nanoparticles Embedded on Mesostructured Silica Films
Authors: Valverde-Aguilar Guadalupe , García-Macedo Jorge A. , Rentería-Tapia Víctor
Published: March 2009

Metallic silver particles in the nanometer size range were obtained in SiO2 matrix by the reduction of AgNO3 with the non-ionic diblock copolymer (Brij 58). Hexagonal mesostructured sol-gel films were synthesized by dip-coating method using the surfactant Brij58 to produce channels into the film, which house the silver nanoparticles. Optical properties of the metallic nanoparticles were studied by UV-Vis spectroscopy, TEM and HRTEM images. The experimental absorption spectrum of the metallic silver nanoparticles exhibits an absorption band located at 438 nm and a shoulder at longer wavelength. The TEM images show randomly distributed silver nanoparticles (Type I) along with some oriented as long line (Type II). Both distributions exhibit a silver oxide shell around of them. The second shell covering the silver core - silver oxide shell system is related to the surfactant. The optical absorption spectrum was modelled using the Gans theory. The fit shows two main contributions related to metallic silver nanoparticles with different axial ratios, and surrounding of a dielectric medium with high refractive index. Presence of the high refractive index silver oxide shell was confirmed by X-ray diffraction technique. The contributions of silver core and silver oxide shell play important roles in the optical properties of the films.
Effect of Iron Substitution on Structure and Optical Properties of Nanocrystalline CaTiO3
Authors: Bandyopadhyay A. , Mondal S. , Pal M. , Pal Umapada , Pal M.
Published: March 2009

Nanocrystalline CaTiO3 powders doped with Fe2O3 have been prepared using a soft chemical route. Precipitation of CaTiO3 nanocrystals has been studied by monitoring the exothermic peak in their DSC spectra. The crystal growth temperature of the samples depends on the concentration of iron. Surface morphology, crystal structure, optical and electrical properties of the nanostructures are investigated. X-ray diffraction study shows that the as-prepared powders are amorphous in nature and CaTiO3 phase formation starts at around 500 0C. Rietveld analysis revealed that the particle size of iron substituted CaTiO3 is in nanometer range. Optical bandgap of the nanostructures varies from 4.3 to 3.7 eV for the variation of iron concentration from 0.05 to 0.2 mole %.
One Pot, Environmentally Benign, Thermal Reaction to Fabricate WSe2 and MoSe2 Nanoplates
Authors: Pol Vilas Ganpat , Pol Swati Vilas , Gedanken Aharon
Published: March 2009

The two dimensional nanoplates of WSe2 and MoSe2 are the result of solid-state thermal
(750oC) reaction between micrometer-sized W or Mo with micro-size Se powder under inert
atmosphere via carving phenomena in a closed reactor. This is a distinct top-down approach
presented for the fabrication of inorganic nanoplates, where micron-sized metal particles having
very high melting and boiling points are converted into a Se–M–Se sandwich structure employing a
single-step, scalable, and environmentally- friendly chemical reaction under autogenic pressure at
elevated temperature (RAPET). The mechanistic elucidation of the creation of WSe2/MoSe2
nanoplates is suggested on the basis of the crystal structure with the support of data obtained from
compositional, structural, and morphological characterizations.
New Approach of the Fundamental Relations Used in the Nano-Indentation Analysis
Authors: Bourbia A. , Bedboudi H. , Draissia M. , Debili M.Y.
Published: March 2009

The instrumented indentation technique is being widely used for the determination of elasto-plastic properties of metallic materials by analyzing located atomic force microscopy (AFM) image area and loading-displacement data of indentation imprints after testing. This data analysis is highly dependent on the method followed for interpretation the loading and unloading curves. We have detailed the two common methods, the Oliver&Pharr method based on a power law and the energetic approach method based on finite elements, in order of understanding the nano-indentation unloading behavior to determine the closer hardness and Young’s modulus of metallic materials..
Characterization of Nano-Biphasic Calcium Phosphates Synthesized under Microwave Curing
Authors: Abdel-Fattah Wafa I. , Reicha Fikry M. , Elkhooly Tarek A.
Published: March 2009

Two biphasic BCP ceramic samples were synthesized by chemical precipitation and microwave curing of calcium deficient hydroxyapatite CDHA under the same pH value and temperature but varied in their initial Ca/P molar ratio. Precipitates were characterization after thermogravimetric analysis, fourier transform infrared spectroscopy, X-ray diffraction, atomic absorption spectroscopy and TEM. Hydroxyapatite (HA) contents were measured for the two biphasic calcium phosphate (BCP) ceramics by sintering the calcium-deficient apatites (CDHA). The results reveal two condensation mechanisms of HPO42- affecting the Ca/P molar ratio after calcination. The X-ray diffraction patterns of BCP powders show the in situ formation of -TCP in the BCP powder. The amount of -TCP phase increases as the initial Ca/P molar ratio decreases due to more calcium deficiency in CDHA structure. The influence of HPO42- incorporation on increasing -TCP phase content after calcination is evaluated. TEM micrographs proved the effect of microwave curing during the preparation process on reducing of particle size to nanoscale range and the destruction of CDHA to finer HA and -TCP particles upon calcination.
Synthesis and Characterization of Vitamin Encapsulated Mesoporous Silica with TEOS
Authors: Kim Chang Woo , Kim Young Hwan , Cha Hyun Gil , Han Young Chul , Kang Young Soo
Published: March 2009

In the past decades, porous materials have attracted great scientific and industrial interest due to their appealing structures and potential applications in separation, purification, catalysis, devices, and so forth. The developing community of ordered mesoporous materials has carried on this exploration of the mesoscopical territory, which promises their unique capacities related to large molecules and their transportation in confined space. Thus rational control and adjustment of pores have been continually focused during the synthesis of ordered mesoporous materials with diverse intrinsic properties. In this work, vitamin C encapsulated mesoporous silica was successfully synthesized with tetraethylorthosilicate (TEOS). TEOS was subjected to sol-gel process in the presence of cetyltrimethylammonium bromide (CTAB). The composition and size of mesoporous silica was controlled by fitting the molar ratio of starting materials. The mesoporous silica can be applied to the field of the cosmetics and bio-medicine as drug delivery.
Self-Assembled ZnO Nanostructure for Field-Emission Devices
Authors: Bhattacharya P. , Varshney D. , Samanta K. , Katiyar R.S.
Published: March 2009

Zinc oxide (ZnO) nanorods on Au patterned Si substrates were fabricated using vapor transport method. The XRD pattern showed the ZnO nanorods were highly c-axis oriented similar to ZnO thin films. The photoluminescence spectrum at 77 K of ZnO nanorods was consisting of the fundamental near band edge emission of ZnO in the UV region along with a broad defect induced emission around green band. The field emission properties of the nanorods showed a current density of 1mA/cm2 at an applied field of 10V/m, which is comparable to other reported values of ZnO nanorods. The patterned gold island formed by self-assembly of polystyrene ball on Si substrate acted as a catalyst in the growth of nanorods as well as stable ohmic contact for field emission.
Effect of TiO2-In2O3 and TiO2-Al2O3 Sol-Gel Supports on the Morphology of Gold Nanoparticles
Authors: Rodríguez-González Vicente , Castillo S. , Morán-Pineda F.M. , Zanella R. , Gómez Ricardo
Published: March 2009

We report the findings concerning the preparation and characterization of Au nanoparticles deposited on sol-gel derived TiO2, TiO2-Al2O3 and TiO2-In2O3 semiconductors. The gold nanoparticles were obtained by the deposition-precipitation method using urea. The mean particle size was determined by HAADF-STEM. The gold nanoparticles ranged form 2.4 to 4.4 nm, and the smallest corresponding to the TiO2-Al2O3 support was 2.4 nm. The effect of support on the growth of the gold nanoparticles was analyzed by HRTEM. The gold nanoparticles showed different shapes depending on the semiconductor supports. Truncated cuboctahedral gold nanoparticles were identified and analyzed.
Synthesis and Photocatalytic Activity of Yb Doped TiO2 Nanoparticles under Visible Light
Authors: Pal Mou , Pal Umapada , Silva Gonzalez R. , Sanchez Mora E. , Santiago P.
Published: March 2009

Developing new semiconductor materials with improved photocatalytic activity is a promising technology for the remedy of environmental pollution. Here we report on the synthesis of Yb containing TiO2 nanoparticles and their catalytic activity under visible light. Highly monodispersed, spherical TiO2 and TiO2 :Yb nanoparticles of 27- 40 nm size range were prepared through controlled hydrolysis of titanium tetrabutoxide (TTB) and characterized by X-ray diffraction (XRD), energy dispersion spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), high angle annular dark field (HAADF), and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) techniques. Average size of the nanoparticles was found to decrease with the increase of Yb doping concentration. The photocatalytic activity of Yb doped TiO2 was evaluated by measuring the degradation rates of methylene blue (MB) under UV and visible lights. Doping with ytterbium ions enhanced significantly the photocatalytic activity of TiO2 nanoparticles for MB oxidation under visible light.
First Principles Calculations of the Electronic and Structural Properties of SnO Nanotubes and Nanorods
Authors: Alvarez-Ramírez Fernando
Published: March 2009

A theoretical study of the electronic and structural properties of single wall SnO one dimensional (1D) nanotubes and nanorods is presented in models with arm chair (n,0) and zig-zag (n,n) chirality. The nanonotube and nanorod models were built setting periodic boundary conditions along the axis of the 1D structures. In both cases, nanotubes and nanorods, the geometry was optimized keeping the periodic cell dimensions constant and relaxing the atomic positions through DFT calculations carried out for various k points, and using the GGA-PW91 functional. The surface charge characteristics of the systems were mapped with the Hirshfeld charge, showing a small tendency towards to increase the outer tin atomic charges, and to reduce the inner oxygen atomic charges of the nanotube with regard to the flat bulk structure charges. The nanotubes shows stable configurations in both chiralities, whereas the nanorod geometry shows a stable configuration only in the (n,0) chirality. The conduction properties were studied as function of the curvature of the 1D tin monoxide structures through the total density of states and the band gap observing a tendency to the larger the nanotube radius the larger band gap.
Energy-Dependent Deformation of Colloidal Silica Nanoparticles under Room Temperature Irradiation with MeV Si Ions
Authors: Cheang-Wong Juan Carlos , Morales Ulises , Reséndiz Eder , López-Suárez Alejandra
Published: March 2009

Spherical submicrometer-sized silica particles were prepared from a reaction mixture containing tetraethoxysilane, ammonia and ethanol, and deposited onto silicon wafers. The properties of these SiO2 particles depend on their size, size distribution and shape. Even if some of these characteristics can be perfectly controlled by appropriate synthesis conditions, several alternative approaches must be explored in order to modify the shape of silica particles. The samples were then irradiated at room temperature with Si ions at different energies (4, 6 and 8 MeV) and fluences up to 5×1015 Si/cm2, at an angle of 45° with respect to the sample surface. After the Si irradiation the spherical silica particles turned into ellipsoidal particles, as a result of the increase of the particle dimension perpendicular to the ion beam and a decrease in the parallel direction. This effect increases with the ion fluence and depends on the electronic energy loss of the impinging ions. We observed that the particle deformation decreases with the beam energy, mainly because our samples were irradiated at room temperature. Thermal effects must be studied in detail in order to elucidate the complete deformation mechanism, as the existence of additional mechanisms related to the electronic energy loss effects can not be excluded.
Influence of Temperature and Pressure on the Possibility of Obtaining Al2O3/Ni-P Nanocomposite through Hot Pressing Process
Authors: Michalski J. , Konopka K. , Gierlotka Stanislaw , Kurzydlowski Krzysztof Jan
Published: March 2009

The influence of sintering temperature and high pressure on Ni-P nanoparticles in Al2O3/Ni-P nanocomposites was investigated in this paper. The fine-grained alumina powder was covered with Ni-P nanoparticles of 20 – 50 nm size by electroless nickel plating. The material was sintered in temperatures from 900 to 1400oC using pressures above 5 GPa. It was found that sintering in such conditions give a possibility to maintain nanometrical size of Ni-P particles. In the case of 1400oC the metallic phase melts and non-uniform grain growth of ceramic was observed. Hot pressing at 900oC allowed for the metal to remain in solid state and ensured uniform microstructures of the nanocomposites, with uniform distribution of nanometrical Ni-P grains in the ceramic matrix. In this temperature the grain growth of the ceramic was not observed. The results are discussed in terms of technology for production of ceramic-metal composites for various applications.
Synthesis of Metal-Ceramic Nanocomposites by High-Pressure Infiltration
Authors: Gierlotka Stanislaw , Palosz Bogdan F. , Swiderska-Sroda Anna , Grzanka Ewa , Kalisz Grzegorz , Fietkiewicz Karol , Stelmakh Svetlana , Lathe Christian
Published: March 2009

A technique of preparation of novel nanocrystalline composites by infiltration of a liquid metal under high-pressure is presented. A porous nanocrystalline body is obtained by compacting nanosized powder of a high-hardness ceramic material under the pressure of 2-8 GPa. The molten metal penetrates into the open pores and crystallizes there upon cooling. As a result the second nano-phase is obtained. Practical aspects of the technique and some properties of the composites are discussed.
Wafer Backside Cleaning Strategies for High-k/Metal Gate Processing
Authors: Vos Rita , Kesters Els , Garaud Sylvain , De Waele R. , Kenis Karine , Lux Marcel , Kraus H. , Snow James , Shamiryan Denis , Catana Gabriela , Deweerd W. , Schram T. , DeGendt S. , Mertens Paul W.
Published: March 2009

In this work the removal of different metallic and particulate contaminants relevant for high-k/metal gate processing is studied. Best cleaning efficiency of both silicon and nitride substrates is achieved using a HF/HNO3-based cleaning resulting in a particle removal efficiency higher than 90% and metal removal down to 1010 at/cm2.
Repair of Porous MSQ (p-MSQ) Films Using Monochlorosilanes Dissolved in Supercritical CO2
Authors: Xie Bo , Muscat Anthony
Published: March 2009

Fourier transform infrared (FTIR) spectroscopy, contact angle, and electrical measurements were used to study porous methylsilsesquioxane (p-MSQ) films (JSR LKD 5109) processed with alkylmonochlorosilanes having chain lengths of one to eighteen carbon atoms dissolved in supercritical carbon dioxide at 155-185 atm and 55-60°C to repair oxygen ashing damage. The FTIR results showed that all chemistries reacted with silanol groups on the surface of the pores producing covalent Si-O-Si bonds. Self-condensation between the alkylsilanols with chain lengths above four carbon atoms produced a physisorbed residue, which was partially removed after rinsing with pure scCO2. The hydrophobicity of the blanket p-MSQ surface was recovered, while the initial dielectric constant of 2.4 for the blanket p-MSQ surface was restored after treatment. With an increase in the length of the alkyl chain, the contact angle increased from 84° to 108° and the dielectric constant measured on metal-insulator-semiconductor capacitors was approximately constant in the range 2.4 ± 0.05. The monochlorosilanes restore the dielectric constant and surface properties of mesoporous p-MSQ and are candidate pore sealing additives.
Via Cleaning Technology for Post Etch Residues
Authors: Sharma B.G. , Prindle Chris
Published: March 2009

Interconnect RC delay is the limiting factor for device performance in submicron semiconductor technology. Copper and low-k dielectric materials can reduce this delay and have gained widespread acceptance in the semiconductor industry. The presence of copper interconnects provides unprecedented challenges for via cleaning technology and requires the development of novel process chemistries for improved device capability.
Barrier and Copper Seedlayer Wet Etching
Authors: Richard Claire Therese , Frank M.M. , Besson Pascal , Serret E. , Hotellier N. , Beverina Alessio , Dumas L. , Broussous Lucile , Kovacs F. , Billon Thierry
Published: March 2009

This paper summarizes the process development of TiN barrier etching in presence of copper, for a thick copper level in BICMOS technology. In an industrial context, we have chosen to use a SC1 chemistry in a spin etch single wafer tool. The SC1 composition and therefore the pH level allows - the barrier to be etched with no metallic residues, ( if not clear this can be a source for shorts) - control of the selectivity between copper and TiN - control of lateral etching under copper
lines, the possible source of open chains by W attack during TiN etch. The electrical results show a robust process according to current specifications, in terms of leakage and via resistance with a fresh chemistry approach. In fact, the recirculation of SC1 is not possible due to substantial concentration changes during processing, high evaporation rate of Ammonia and high decomposition rate of Peroxide in the presence of copper on surface wafer.
Advanced Surface Cleaning Strategy for 65nm CMOS Device Performance Enhancement
Authors: Arnaud F. , Bernard H. , Beverina Alessio , El-Farhane R. , Duriez B. , Barla Kathy , Lévy Didier
Published: March 2009

This paper investigates low temperature cleaning steps solutions (T°<30°) developed to enhance the 65nm transistor performance. A complete cleaning recipes optimization is realized in term of silicon consumption and defectiveness for pre-furnace clean (RCA or HFRCA), post gate etch clean PGEC (HF-SPM-SC1) and post ash clean PAC (SPM–SC1) operations. The silicon recess and the dopants consumption are reduced by using low temperature SC1 steps. Transistor drivability is improved by 8% and 7% for NMOS and PMOS respectively.
Evaluation of Wafer Drying Methods for GIGA-LEVEL Device Fabrication
Authors: Kim Gyu Hyun , Choi Geun Min , Song Young Wook
Published: March 2009

This study deals with drying induced water marks dependency on the last cleaning methods, substrate conditions, and drying pre-step delaying times, which are supposed to become a big issue with down scaling of device geometry. The data show that water marks induced by drying failure increase with increasing contact angle on the various surfaces. They are mainly composed of either silicon oxide only or silicon oxide with organic compounds. The former is removed by a dilute HF and/or hot SC-1 treatment and the latter is removed by organic removal cleaning followed by dilute HF etching.
Performance of a Linear Single Wafer IPA Vapour Based Drying System
Authors: Fyen Wim , Arnauts Sophia , Holsteyns Frank , Doumen G. , Vereecke Guy , Van Steenbergen Jan , Mertens Paul W.
Published: March 2009

In this paper, a single wafer linear IPA vapour based vertical drying technique is presented. Using salt residue tests the performance of this technique is evaluated and compared to spin drying. The equivalent film thickness of evaporating liquid is below 0.05µm for blanket wafers, which is two orders of magnitude less than with spin drying. It is also shown that the presence of surface topography (200nm high TEOS features on Si covered with a chemical oxide) does not significantly influence the drying performance. A study of the process window shows that for the setup evaluated in this work best performance is achieved when the IPA/N2 flow rate is above 20 liters per minute and the drying speed is below 8 mm/s. With a manual prototype already very good particle performance is demonstrated.
Occurrence of Arsenic-Based Defects and Techniques for Their Elimination
Authors: Goh Felicia , Lim Christopher , Sih Vincent , Ismail Zainab , Chooi Simon Y.M.
Published: March 2009

Arsenic based defects were found on the surfaces of advanced CMOS patterned wafers after the pre-silicidation HF clean. Investigations into the mechanism of formation were done using representative As-implanted bare silicon, polysilicon and HDP silicon oxide films. The nature and composition of these As-based defects are believed to be arsenic and arsenic oxide. Methods of defect removal include the application of hydrogen peroxide containing solutions and hydrogen plasma dry cleaning.