bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Free Energy Differences Between Crystalline Phases Using the Lattice-Switch Monte Carlo Method
Authors: Ackland G. J. , Wilding N. B. , Bruce A. D. 
Published: April 2011

ABSTRACTA new method [1] of calculating the free energy difference between two crystalline structures is presented. The method involves a single simulation which repeatedly transforms the system between the two crystal phases. Since the configurations of both structures are sampled within a single Monte Carlo process, the difference between their free energies can be evaluated directly from the ratio of the measured probabilities of each. Compared with traditional techniques, the method is most advantageous when applied to highly anharmonic systems. To illustrate the method, an application to the free energy difference between the fee and hep structures of hard spheres is described.
Novel Structure of MgSe in the Multimegabar Regime: Positional Parameter Determination
Authors: Ruoff Arthur L. , Li Ting , Narayana Chandrabhas , Luo Huan , Greene Raymond G. 
Published: April 2011

ABSTRACTThe structural transformations in the II-VI compound MgSe have been studied under pressure using energy dispersive x-ray diffraction. MgSe transforms ‘continuously’ from the rocksalt (Bl) structure to a FeSi (B28) or Au-Be structure beginning at 99 ± 8 GPa. At 202 GPa, MgSe is approaching 7-fold coordination withu= 0.0828 andw= 0.4173. The method for intensity calculation of the diffraction peaks is presented. Using the Birch equation, the equation of state to 146 GPa was determined with Bo= 62.8 + 1.6 GPa and Bo′ = 4.1.
Pressure as a Probe of the Glassy State of Ferroelectrics with Random Site Disorder
Authors: Samara G. A. , Hansen L. V. 
Published: April 2011

ABSTRACTResults on lanthanum-modified lead zirconate-titanates (PLZTs) have revealed a pressure-induced crossover from a normal ferroelectric to a relaxor state and the continuous evolution of the dynamics and energetics of the relaxation process. This crossover appears to be a general feature of soft mode ferroelectrics with random site dipolar impurities or polar nanodomains and results from a large decrease in the correlation radius among polar nanodomains - a unique property of soft mode ferroelectrics.
Surface and bulk properties of boride/nitride nanoscale films
Authors: Adrievski R. A. 
Published: April 2011

ABSTRACTNanoscale TiB2/TiN films have been prepared by d.c. and r.f. magnetron non-reactive sputtering and examined by TEM, SAED, SEM, AES, XPS, XRD, AFM as well as nanoindentation. Attention has been focused on both bulk and surface physical-mechanical properties. The effect of the latter on the nanoindentaion test results seems to be very important. Two types of film fracture under a Vickers indentor connected with homogeneous and inhomogeneous deformation have been described.
Drifts surface characterization of Zincblende nanostructured GaN
Authors: Gonsalves Kenneth E. , Carlson Greg , Baraton Marie-Isabelle 
Published: April 2011

ABSTRACTThe use of GaN/polymer nanocomposites in optoelectronics requires a perfect control of the GaN dispersion in the polymer matrix. This cannot be achieved without a good knowledge of the first atomic layer of the GaN nanoparticles. This paper reports the characterization of the surface chemical species of a GaN nanosized powder by diffuse reflectance infrared Fourier transform spectrometry.
Block Copolymer Monolayers at Surfaces
Authors: Saunders R. S. , Kent M. S. , Small J. H. 
Published: April 2011

ABSTRACTMonolayers on surfaces have become a topic of considerable interest over the last few years. This has arisen from the need to functionalize a surface so that its properties are different than the properties of the bulk material. This research has involved functionalizing copper surfaces to enhance adhesion to epoxy. We have accomplished this using block copolymers made by Ring-Opening Metathesis Polymerization (ROMP). In this paper we discuss the synthesis and characterization of these block copolymers and their segregated monolayer conformation at copper surfaces, including NMR, GPC, SANS, neutron reflectivity, and TOF-SIMS. We also discuss a comparison of block copolymers to SAMS for surface functionalization.Monolayers on surfaces have become a topic of considerable interest over the last few years. This has arisen from the need to functionalize a surface so that its properties are different than the properties of the bulk material. This research has involved functionalizing copper surfaces to enhance adhesion to epoxy. We have accomplished this using block copolymers made by Ring-Opening Metathesis Polymerization (ROMP). In this paper we discuss the synthesis and characterization of these block copolymers and their segregated monolayer conformation at copper surfaces, including NMR, GPC, SANS, neutron reflectivity, and TOF-SIMS. We also discuss a comparison of block copolymers to SAMS for surface functionalization.
Microstructure and properties of oxide ceramic-based nanocomposites with transition metal nanoparticles
Authors: Sekino T. , Etoh S. , Choa Y.-H. , Niihara K. 
Published: April 2011

ABSTRACTTransition metal particles dispersed oxide ceramic nanocomposites A12O3/Co and ZrO2/Ni, in which metal content is less than 20 vol%, have been fabricated by the reduction and sintering of composite powders. These powder mixtures were prepared by solution chemical processes to obtain suitable structure for ceramic/metal nanocomposites. Nickel or cobalt nitrate, as a source of metal dispersion, was dissolved into alcohol and mixed with alumina or zirconia powder. These powders were reduced by hydrogen and successively hot press sintered. Nanometer-sized Co or Ni particles were mainly dispersed at the matrix grainboundaries. Fracture strength was improved by dispersing metal particles due to microstructural refinement, whereas toughness was increased by incorporating large metals. Ferromagnetic responses with enhanced coercive force were also observed for these composites.
Synthesis of Nanoscaled Powders by Laser-Evaporation of Materials
Authors: Riehemann W. 
Published: April 2011

ABSTRACTUltra fine powders with particle diameters less than 100 nm are becoming increasingly important for various electronic, magnetic and chemical applications as well as in nanostructured materials with extremely fine grained components. Nowadays there are a lot of methods available to synthesize nanoscaled powders. One of the most versatile production methods delivering clean particle surfaces is laser evaporation. Interaction of high intensity laser beams with materials leads to evaporation and subsequent condensation of very small mostly spherical particles with diameters in the order of 10 nm. This means specific surfaces of the powders in the order of 100 m2/g. Depending on the lasers intensity, the surrounding gas, its pressure, and the evaporated material the particles have mean diameters ranging from 4 to 20 nm. Their distribution is generally lognormal with a geometrical standard deviation in the narrow range between 1.5 and 1.7. These properties of the powders can be explained by their originating mechanism, nucleation and particle growth in the surrounding gas. With this method nanosized powders of various materials can be produced like pure metals, alloys, metal oxides, other ceramics and new phases which are probably stabilized by the small particle size. Using a 1 kW - Nd:YAG - laser powder production rates of up to 100 g/h can be achieved for alumina. Contrary to other synthesis methods e.g. the sol-gel method the produced nanoparticles are in particular free of solvents or other residuals. This makes laser synthesised powders extremely usefiil for catalytic or gas sensor applications where defined surface qualities are necessary.
Preparation and properties of phenytoin silica complex nanoparticles
Authors: Goto H. , Isobe T. , Senna M. 
Published: April 2011

ABSTRACTA sparingly soluble model drug, phenytoin (5,5-diphenyl-hydantoin, denoted as PT), was added during hydrolysis and polycondensation of tetra orthoethyl silicate (TEOS). The average size of the composite primary particles after in situ recrystallization of PT and gelation of silica was 2–3nm. The extent of hydrogen bond (HB) in PT was reduced after the complex formation (CF), while many PT molecules were attached by HB on the surface of silica gel. The apparent solubility to ethanol decreased to 29%∼18% by CF. The firstorder rate constant of dissolution of PT into H20 increased by CF up to 40 times. Addition of acrylamide also enhanced the dissolution rate. Mechanisms of faster dissolution were discussed in terms of the hydrogen bond reformation and microstructure.
Nanoparticulate film precursors to cis solar cells: Spray deposition of Cu-In-Se colloids
Authors: Schulz D. L. , Curtis C. J. , Flitton R. A. , Ginley D. S. 
Published: April 2011

ABSTRACTThe use of nanoparticle colloids for spray deposition of Cu-In-Se precursor films and subsequent thermal treatment to form CuInSe2 (CIS) films has been investigated. In the present study, the metathesis reaction between Na2Se in methanol and metal salts (i.e., Cu(BF4)2 and/or InI3) in pyridine produced CuSe, In2Se3, and CuInSe2.5 nanoparticle colloids. Purified colloid was sprayed onto heated molybdenum-coated sodalime glass substrates to form CuInSe2.5/Mo and In2Se3/CuSe/Mo precursor films. These precursor films were subjected to various thermal treatments in an effort to produce large-grained CIS films from the nano-sized precursors. The annealed CIS films were characterized by scanning electron microscopy (SEM) and x-ray diffraction (XRD). Results of this continuing effort will be discussed.
Control of particle adhesion to surfaces by depositing nanometric interfacial layers
Authors: Ata Ali , Fitz-Gerald J. , Singh R. K. 
Published: April 2011

ABSTRACTThe influence of nano-thick hydrophilic or hydrophobic films on adhesion properties of particles to surfaces has been investigated. Al2O3 and Ag layers were deposited on Ag and Al2O3 core particles, respectively by a modification of pulsed laser deposition technique. The as-received and surface-modified particles were further coated by a secondary process with submicron Al2O3 particles. We observe that deposition of hydrophobic or hydrophilic surfaces affects the surface coverage of secondary particles on core particles and hence the adhesion characteristics.
Optical properties of nonspherical silver nanoparticles embedded in a plasma polymer thin film matrix
Authors: Heilmann A. , Quinten M. , Kiesow A. 
Published: April 2011

ABSTRACTSilver nanoparticles which are embedded in a plasma polymer matrix were obtained by transmission electron microscopy. Their sizes and shapes were analyzed with optical image processing. As most of the particles appeared as elongated rotational ellipsoids, the major and minor half axes were determined for each particle. The model of Gans in the Rayleigh approximation was used to calculate the extinction spectra for each investigated particle using the data from the image processing. Various spectra for 1049 silver particles were added to get a total extinction spectrum which was in good agreement with the experimental spectrum.
Optical properties of gold-containing Poly(acrylic acid) composites
Authors: Scholz S. M. , Carrot G. , Hilborn J. , Dutta J. , Valmalette J.-C. , Hofmann H. , Luciani A. 
Published: April 2011

ABSTRACTThere is strong interest in the research & development of the particle/polymer composite technology for functional applications. Current activities are directed towards polymer assisted synthesis of ultrafine metal or semiconductor particles in solution, with an ultimate goal to arrange the particles in a matrix in well-controlled fashion, for possible electro-optical applications. In the present work the optical properties of poly(acrylic acid) polymers containing gold chloride have been investigated. This material system permits synthesis of gold nanoparticles by the reduction of gold chloride. The polyelectrolyte initially forming upon mixture of the reagents shows a gelating behavior. In-situ reduction into gold clusters can be achieved by several ways. Rheological properties, optical absorption/extinction spectra as well as photoluminescence and photoluminescence excitation spectra will be presented and discussed. Different possible combinations of gold ligands and co-ordinations states will be considered in the discussion. Gold may be present in the form of complexes, to the polyelectrolytes, or in form of nanoparticles or larger aggregates depending on the relative concentrations of the reagents and polymer molecular weight.
In-Situ DLTs Measurement of Metastable Coupling between Proton-Induced Defects and Impurities in n-Si
Authors: Kono K. , Kishimoto N. , Amekura H. 
Published: April 2011

ABSTRACTDeep centers related to proton-induced defects and impurities in n-Si were investigated using an in-situ DLTS system. The measurement system was installed in the beamline of NRIM cyclotron. Floating zone (FZ) or Czochralski (CZ) Si was irradiated at a flux of about 30 nA/cm2. The total dose was varied between 1.0 ∼ 7.2 × 1013 ions/cm2. Samples were irradiated at 200 K or 300 K. Their defect concentrations were determined by in-situ DLTS. Quantitative relationship between oxygen and phosphorus concentration and defect creation rates were presented. Isothermal annealing at 250 K was conducted for a CZ-Si sample and the resuflt indicated the meta-stable nature of the carbon defect complex.
Change in yhe Optical Properties of Sapphire Induced by Ion Implantation
Authors: Ila D. , Williams E. K. , Sarkisov S. , Poker D. B. , Hensley D. K. 
Published: April 2011

ABSTRACTWe have studied the formation of nano-crystals, after implantation of 2.0 MeV gold, 1.5 MeV silver, 160 keV copper and 160 keV tin into single crystal of A12O3. We also studied the change in the linear optical properties of the implanted Al2O3 before and after subsequent annealing by measuring the increase in resonance optical absorption. Applying Doyle's theory and the results obtained from Rutherford backscattering spectrometry (RBS) as well as the full width half maximum of the absorption band from Optical Absorption Photospectrometry (OAP), we measured the average size of the metallic clusters for each sample after heat treatment. The formation and crystallinity of the nanoclusters were also confirmed using transmission electron microscopy (TEM) technique.
Ion Beam Synthesis Of Cds, ZnS, And PbS Compound Semiconductor Nanocrystals
Authors: White C. W. , Budai J. D. , Meldrum A. L. , Withrow S. P. , Zuhr R. A. , Sonder E. , Purezky A. , Geohegan D. B. , Zhu J. G. , Henderson D. O. 
Published: April 2011

ABSTRACTSequential ion implantation followed by thermal annealing has been used to form encapsulated CdS, ZnS, and PbS nanocrystals in SiO2 and Al2O3 matrices. In SiO2, nanoparticles are nearly spherical and randomly oriented, and ZnS and PbS nanocrystals exhibit bimodal size distributions. In Al2O3, nanoparticles are facetted and oriented with respect to the matrix. Initial photoluminescence (PL) results are presented.
Formation of Pb Inclusions in Si by Ion Implantation
Authors: Touboltsev V. S. , Johnson E. , Dahmen U. , Johansen A. , Sarholt L. , Xiao S. Q. 
Published: April 2011

AbstracrSi<110> single crystals were implanted at a temperature of 835 K with 150 keV Pb+ ions to a fluence of 1·1020 m−2 corresponding to an average concentration of 2–3 at%. The implanted samples have been studied by Rutherford Backscattering (RBS)/channeling and transmission electron microscopy (TEM) techniques. In as-implanted samples the main fraction of implanted Pb was located on substitutional sites in the Si matrix thus providing a highly supersaturated solution of Pb in Si. Spontaneous precipitation of Pb, giving rise to formation of nanosized Pb inclusions, was found to take place only in the peak region of the implantation. TEM analysis showed that the Pb precipitates had sizes from about 2 to 20 nm and that they grew in parallel cube orientation relationship with the host matrix. The shape of the inclusions was found to be approximately cuboctahedral with poorly developed {111} and {100} facets.In-situ RBS/channeling heating/cooling experiments on both as-implanted samples and samples previously furnace-annealed at 1175 K showed a distinct melting/solidification hysteresis of the Pb inclusions around the bulk melting point for Pb at 600 K. These results were verified by in-situ TEM heating/cooling experiments on as-implanted samples.
Modification of Wetting Property of Polycarbonate by Means of Ion Beam Implantation and Storage in Different Gas Environments
Authors: Poirier A. , Ross G. G. , Bertrand P. , Wiertz V. 
Published: April 2011

AbstracrThe wetting property of polymers is very important in different applications such as biomaterials, textiles, aerospace (fluid management and materials processing in microgravity), and thin film adhesion. Therefore, there is a strong interest in the development of a new technology for the modification at will of this property. The use of low energy ion beams allows the modification of the first surface atomic layers. Nitrogen ions of 500 eV/at. were used to bombard the surface of polycarbonate (PC) samples to a fluence of 5×1016 at/cm2. Five different environments (oxygen, nitrogen, argon, dry air and vacuum) were used to store the samples for some hours (1 to 24 hours) after the implantation. Aging studies of the contact angle (advancing and receding) have shown that the environment gas influences the long term value of the contact angle and helps to maintain the stability of the treated surfaces with the passage of time. XPS and ToF-SIMS have been used to study the chemical effects of both N2+ ion irradiation and storage gas surrounding the samples. The results show faster aging in the case of the samples stored in vacuum, a harmful effect of nitrogen gas on the treatment and the formation of new chemical species for all treatments.
Size Dependence of Bombardment Characteristics Produced by Cluster Ion Beams
Authors: Seki T. , Tanomura M. , Aoki T. , Matsuo J. , Yamada I. 
Published: April 2011

ABSTRACTCluster ion beam processes provide new surface modification techniques, such as surface smoothing, high rate sputtering and very shallow implantation, because of the unique interactions between cluster and surface atoms. To understand interactions with cluster and surface, Scanning Tunneling Microscope (STM) observations have been done for single impact traces.Highly Oriented Pyrolitic Graphite (HOPG) surfaces were bombarded by carbon cluster ions (Va≤300kV), and large ridges and craters have been observed as a result of single cluster ion impact. The impact site diameters are proportional to the cluster size up to 10 atoms, and increase drastically for cluster sizes above 10. This indicates that non-linear multiple collisions occur only when a local area is bombarded by more than 10 atoms at the same time.
Aluminum and Electron-Irradiation Induced Deep-Levels In N-Type And P-Type 6H-Sic
Authors: Gong Min , Beling C. D. , Fung S. , Brauer G. , Wirth H. , Skorupa W. , You Zhi-Pu 
Published: April 2011

AbstractTwo deep levels, located at Ev+0.26eV and Ec-0.44eV, in Al-implanted n-type samples and one at Ev+0.48eV in p-type samples have been observed by the deep level transient spectroscopy. The level of is identified as the shallower aluminum-acceptor. The 1.7 MeV electron-irradiation, used as a probe to distinguish the implantation induced deep-levels, induces at least six electron traps in the n-SiC and one hole-trap in the p-type material. The peak positions of these deep-levels in DLTS spectra are quite different from those induced by Al-implantation. This result suggests that various damages are formed after heavy ion (Al) and light particle (e) irradiation.
New Approach to “High-Temperature” Quantum Switch and Quantum Field Effect Transistor
Authors: Meilikhov E.Z. , Aronzon B.A. , Bakaushiin D.A. , Ryl'kov V.V. , Vedeneev A.S. 
Published: April 2011

AbstractWe report results of studying some natural properties of highly disordered mesoscopic systems which seem to be promising for elevating quantum device work temperatures up to 77-300 K. They are FET-type Si-MNOS (metal-nitride-oxide-semiconductor) structures with built-in charge concentrations being so high that the systems remain to be strongly disordered even at room temperature. Disorder of studied structures could be controlled by varying charged traps concentration at the SiO2-Si3N4 interface that induce strong potential fluctuations. Important feature of the structures is the possibility to vary the built-in charge over a wide range (up to 1013 CM−2) that results in varying the disorder range. The conductance of such a system is shown to be controlled by the single small quantum-sized region with a ballistic transport which is a saddle-point region of the fluctuation relief. Narrowness of that “bottle neck” (comparable with the electron wavelength) results in quantizing conductance of the structure, and if the disorder is high enough, the conductance for some gate voltages shows a real tendency to reach a plateau at the quantum value e2/h. What is important, that tendency occurs a∼t high temperatures (77-300 K).
Recombination Strength at Intra and Intergrain Defects in Crystalline Silicon Investigated by Low Temperature Lbic Scan Maps
Authors: Perichaud I. , Martinuzzi S. 
Published: April 2011

AbstractAnnealing of multicrystalline silicon wafers in argon at temperatures higher than 800°C increases the recombination strength of extended defects irreversibly, while external gettering techniques applied at the same temperatures reduce their recombination strength. It is observed that in the light beam induced current (LBIC) scan maps at 80 K the contrast of some extended defects in raw samples is enhanced and additional defects are detected. The same features of defects are revealed by the LBIC maps of raw samples at 80 K as well as at 300 K after annealing. In other words, the LBIC scan maps at low temperature detect “sleeping” defects, which do not recombine at 300 K, but which are activated by thermal treatments during processing steps. The results can be explained by the Shockley-Read-Hall statistic involving the presence of deep and shallow energy levels in the band gap associated with the impurity-defect interaction.
Controlled Surface Fermi-level on the SeS2-passivated n-GaAs (100)
Authors: xi Sun Jing , Himpsel F. J. , Kuech T. F. 
Published: April 2011

AbstractSelenium disulfide surface treatment can unpin the surface Fermi-level on n-GaAs (100) surfaces, resulting in a reduction in the surface band bending. The long-term stability of the surface Fermi-level unpinning has been studied using photoreflectance spectroscopy under room ambient conditions. Our results show that the SeS2-treated n-GaAs (100) surface is stable up to four months with negligible shift in the surface Fermi-level being noted. The mechanism of the long-term stability is attributed to the layered surface structure formed on the SeS2-treated n- GaAs (100) surface. The chemical structure of the passivated surface was determined by synchrotron radiation photoemission spectroscopy. The outermost layer of sulfur and arsenicbased sulfides and selenides may protect the electronic passivating layer, which consists of gallium-based selenides, from interaction with the atmosphere.
Whole-field Displacement Measurement Techniques for Thermal Deformation Analyses of Electronic Packages
Authors: Han Bongtae 
Published: April 2011

ABSTRACTFeatures and recent developments of various photomechanics methods are reviewed for thermal deformation analyses of electronic packages. Applications to diverse problems are illustrated to demonstrate wide applicability of the methods. The whole-field displacement information, with various sensitivity and resolution scales, is ideally suited for the deformation study of a broad range of problems in deformation analyses of electronic packaging. The methods are mature and they can be practiced routinely. A more extensive range of applications are anticipated.