bluuebunny/crossref_metadata_2025_split huggingface dataset:
Particle Size and Oxidation in CoNi Nanoparticles
Authors: Patel Jalpa , Farrell Dorothy , Parkin Ivan P. , Pankhurst Quentin A. 
Published: June 2019

AbstractCobalt nickel nanoparticles with an oxide shell were prepared by polyol reduction syntheses with varying heating rates, reflux times, surfactants, and reagent concentrations. Differences in particle formation temperature, as evidenced by the reaction medium changing color from violet to black, the UV-Vis absorption spectra of aliquots of reaction media extracted throughout the synthesis reaction, and the colloidal stability of the particle dispersions were observed when the surfactant was changed between otherwise identical reactions. These changes in the reaction kinetics, and therefore the particle sizes of the different samples, also resulted in varying magnetic properties and air stabilities of the samples. Particles with diameters of 15 nm, synthesized using oleic acid, displayed exchange biasing and enhanced coercivity below 50 K, with Hex = 650 Oe and an increase in Hc from 570 Oe to 910 Oe after cooling in field to 2 K. These particles were stable in air over a period of at least five months, showing no change in magnetic moment. Smaller (6 nm) particles synthesized with the same surfactant did not exhibit exchange biasing after field cooling and experienced degradation of their magnetic properties upon exposure to air for one month. Particles synthesized with trioctylphosphine and mixtures of trioctylphosphine and oleic acid were 5 nm and formed the most stable dispersions, but oxidized upon drying in air to non-ferromagnetic phases.
Surface Effects on the Magnetic Behavior of Nanocrystalline Nickel Ferrites: The Effect of Surface Roughness and Dilution
Authors: Nathani H. , Misra R.D.K. , Egelhoff W.F. 
Published: June 2019

AbstractThe paper describes the surface roughness and dilution effects on the magnetic behavior of nanocrystalline nickel ferrites studied by SQUID magnetometer. Two different kinds of measurements were performed: (a) zero-field cooling (ZFC) and field cooling (FC) magnetization versus temperature and (b) magnetization as a function of the applied field. The analysis of magnetic measurements indicate that while the superparamagnetic behavior is retained by nanocrystalline ferrites of different surface roughness (0.8-1.8 nm) at 300K, the hysteresis loop at 2K becomes non-squared and the coercivity increases with increase in surface roughness. This behavior is discussed in terms of broken bonds and degree of surface spin disorder. In diluted dispersion systems containing 10-40% nickel ferrite in a polyethylene matrix, the interparticle attractions continue to be dominant even when the concentration of nickel ferrite is 10 wt.% in the diluted system. The general magnetic behavior of diluted dispersion system is similar to the undiluted system; however, coercivity, remanence, and saturation magnetization are altered. These changes in the magnetic data are ascribed to magnetization interactions that encourage flux closure configuration.
DNA Separation Using Gold/Magnetic Iron-oxide Composite Nanoparticles
Authors: Kinoshita Takuya , Seino Satoshi , Otome Yohei , Mizukoshi Yoshiteru , Nakagawa Takashi , Nakayama Tadachika , Sekino Tohru , Niihara Koichi , Yamamoto Takao A. 
Published: June 2019

AbstractAmounts of oligonucleotides adsorbed onto the Au/γ-Fe2O3 composite nanoparticles synthesized by gamma-ray irradiation and picked up by a magnet were evaluated using fluorescence technique. The adsorbing capacity of the oligonucleotides on our nanoparticles are larger than a commercial magnetic beads for a separation of biomolecules.
Autogenerated Air Bubbles for the Spontaneous Formation of Nanostructures
Authors: Yoon Seok Min , Choi Hee Cheul 
Published: June 2019

AbstractIn this paper, a novel mild synthetic route was tentatively designed to achieve both shape and dimension-defined nanostructure such as nanorods, nanowires and nanocircles which were fully characterized by AFM and TEM. Bubbles, which are automatically generated when water is mixed with ethanol by a simple shaking, act as a nanoreactor to produce these nanostructures. Fe containing nanowire, nanorod and nanocircle are successfully prepared by using this method. Autogenerated bubble-mediated formation of nanostructures has advantages over conventional methods in terms of short reaction time, low energy consumption and absence of complicated experimental equipments.
Synthesis of GaS Nanoparticles from a Single-Source Precursor [Ga(S2CNEt2)3/
Authors: Malik Mohammad Azad , O'Brien Paul , Mlondo Sibusiso N. , Revaprasadu Neerish 
Published: June 2019

AbstractGaS nanoparticles have been synthesized by thermolysis of [Ga(S2CNEt2)3] in 4- ethylpyridine. Their absorption spectrum give a band edge at 440 nm (band gap,3.0 eV). XRD pattern showed abroad peaks corresponding to cubic phase of GaS. TEM images confirmed the crystalline nature of particles with narrow size distribution (5.4 nm ± 0.7 dia). To our knowledge this the first time that GaS nanoparticles have been prepared.
Self-Peeling of Porous Nickel Foam from the Electrochemically Etched Porous Silicon
Authors: Zhang Xi , Tu King-Ning 
Published: June 2019

AbstractA low-doped p-type silicon wafer was wet-etched to form macropores in a high-aspect-ratio, straight and parallel manner along the Si (100) direction. It was then plated in aqueous alkaline solution containing Ni2+. Metallic Ni was rapidly deposited in the macropores on the sidewall surface without using a reducing agent or activation treatment at slightly elevated temperature. After being immersed for certain duration, the single crystalline Si of sidewalls was replaced by polycrystalline Ni while the initial porous structure was still maintained. When Ni became dominant in the entire porous regime, the porous film more than 200 μm thick was discovered to be able to peel off very easily from the Si substrate beneath. In this way, a piece of nickel foam with straight pores of very high aspect ratio is self-formed and self-peeled.
In-Situ Tem Study of Interface Sliding and Migration in an Ultrafine Lamellar Structure
Authors: Hsiung Luke L.M. , Nieh T.G. 
Published: June 2019

AbstractThe stability of interfaces in an ultrafine TiAl-(y)/Ti3Al-(α2) lamellar structure by straining at room temperature has been investigated using in-situ straining techniques performed in a transmission electron microscope. The purpose of this study is to obtain experimental evidence to support the previously proposed creep mechanisms in ultrafine lamellar TiAl alloys based upon the interface sliding in association with a cooperative movement of interfacial dislocations. The results have revealed that both the sliding and migration of lamellar interfaces can take place simultaneously as a result of the cooperative motion of interfacial dislocations.
Properties of Nanoscaled Multiphase Structures and Non-Equilibrium Solid Solutions Obtained by Severe Plastic Deformation [Abstract + Supplemental Data]
Authors: Sauvage Xavier , Quelennec Xavier , Jessner Peter , Wetscher Florian , Pippan Reinhard 
Published: June 2019

AbstractGrain size reduction induced by severe plastic deformation (SPD) and the resulting mechanical properties have been widely investigated for pure metals but less is known and reported about multi-phase materials. To study the grain size reduction mechanisms in multiphase structure subjected to SPD, two copper based composites (Cu-10%Fe and Cu-43%Cr) were severely deformed by torsion under high pressure. The grain size achieved with these composite materials is much smaller than in pure metals. It is for example in a range of 10 to 20 nm for the Cu-43%Cr composite, e.g. one order of magnitude lower than in pure Cu processed by SPD. Three dimensional atom probe data show also the formation of non equilibrium supersaturated solid solutions. The mechanisms of the deformation induced intermixing are discussed together with its influence on the mechanical properties.
Mechanical Properties of Ni-P/Diamond Composite Films Processed by Electro-less Plating Method
Authors: Cho Jin Ki , Yoo Mi Sun , Kim Moon Tea , Beak Seung Roung , Kang Sung Goon , Kang Chan Hyoung 
Published: June 2019

AbstractIn this investigation, we carried out an experiment on the process and properties of Ni-P/Nano-Diamond(ND) composite coating with plating conditions.The particle size of nano diamond(ND) by electric explosion method was about 3-8nm size, but these were very easily agglomerated due to high surface energy of ND particles.The ND particles agglomerate diameter (min) were successfully dispersed by ultrasonic dispersion method, after the 400W, 24kHz , 30min ultrasonic treatment.The best dispersibility of ND powder suspension was obtained when the NDconcentration was loaded 1g/l, and ultrasonic dispersion time was 30min, and pH 5. The experimental results revealed that ND composite platings had the remarkable differences such as surface roughness, morphology and friction coefficient compared to conventional diamond-free electroless Ni-P plating.The best mechanical properties were obtained when the concentration of ND powder was 1g/l and the ultrasonic treatment time was 30min and pH of the plating solution was 5.From these results, we were confirmed that the ND particles were uniformly co-deposited in the Ni-matrix when electroless Ni-P/ND composite plating was deposited by the best plating conditions.
Residual Stress Distribution, Intermolecular Force, And Frictional Coefficient Maps In Diamond Films: Processing-Structure-Mechanical Property Relationship
Authors: Gupta Sanju , Williams Oliver , Patel R. J. , Bohannan E. , May P. W. 
Published: June 2019

AbstractCarbon in its various forms, specifically nanocrystalline diamond, may become a key material for the manufacturing of micro- and nano-electromechanical (M/NEMS) devices in the 21st Century. In order to utilize effectively these materials for M/NEMS applications, understanding of their microscopic structure and physical (mechanical properties, in particular) become indispensable. The micro- and nanocrystalline diamond films were grown using hot-filament and microwave chemical vapor deposition techniques involving novel CH4 / [TMB for boron doping and H2S for sulfur incorporation] in high hydrogen dilution chemistry. To investigate residual stress distribution and intermolecular forces at nanoscale, the films were characterized using Raman spectroscopy and atomic force microscopy in terms of topography, force curves and force volume imaging. Traditional force curve measures the force felt by the tip as it approaches and retracts from a point on the sample surface, while force volume is an array of force curves over an extended range of sample area. Moreover, detailed microscale structural studies are able to demonstrate that the carbon bonding configuration (sp2 versus sp3 hybridization) and surface chemical termination in both the un-doped and doped diamond have a strong effect on nanoscale intermolecular forces. The preliminary information in the force volume measurement was decoupled from topographic data to offer new insights into the materials's
Optical Coating Properties for Enhanced Blown-Sand Abrasion Resistance
Authors: Drew Christopher , Bosselman Suzanne , Ziegler David 
Published: June 2019

AbstractLenses and other transparent optical materials suffer rapid damage when subjected to blowing abrasive particulates. The time-scale of these impact event falls between typical scratch tests (less than 1m/s) and ballistic tests (100s of m/s) and has not been studied in depth to date. Polymeric lens materials like polycarbonate are usually treated with a scratch-resistant coating, which is commonly silica-based. The coating provides some protection, yet is not sufficient at resisting abrasion from blown sand in most commercial products. We demonstrate that silicone elastomeric coatings are superior to polycarbonate and silica glass at resisting damage by blown sand particles. Sand abrasion tests were conducted using a custom-built test apparatus that exposes the sample to 400 micron diameter quartz silica moving at 16.5 m/s (approx. 38 mph). Scanning electron microscopy revealed the presence of small cracks and pits in polycarbonate, coated polycarbonate, and silica glass after sand exposure. No such damage was observed in the silicone-coated samples after an identical exposure.We speculate that the elastic tensile strain at the surface is an important predictor of the material response at the time-scale of the impact. A simple mathematical model was developed using a momentum balance pre- and post-impact, and was used to approximate the maximum deformation and impact time-scale. A semispherical interaction volume was used in the model with a radius of 1.5x the particle diameter, determined through profilometry experiments. The material’s resistance to deformation was measured experimentally through a static mechanical test using a spherical indenter to represent the particle. Tensile tests were performed on both materials to identify the maximum elastic strain.Additionally, dynamic mechanical tests were performed to confirm that the mechanical behavior at long time-scales was valid at shorter time-scales of the impacts. DMA curves were shifted using the WLF equation. Profilometry and scanning electron microscopy (SEM) imaging were used to confirm the presence or absence of blown-sand induced damage.
Protection of Glass from Scratches: The Use of a Hard, Thin Coating to Minimize Damage
Authors: Tartivel Ronan , Reynaud Emmanuelle , Grasset Fabien , Sangleboeuf Jean-Christophe , Rouxel Tanguy 
Published: June 2019

AbstractUsed throughout human history, glass has recently been reconsidered as a major structural material as shown by the large window surfaces in use nowadays in vehicles and buildings. Its transparency hides a significant mechanical drawback, however: Brittleness, which arises from surface flaws. In times where reducing the weight and increasing the lifetime of structures is a growing concern, any strategy to increase the toughness of glass is of interest.Our study aims at coating glass surfaces with a hard, thin, transparent protective layer in order to minimize the density of surface flaws. A reverse micro-emulsion synthesis was used to produce a dispersion of colloidal silica nanoparticles (∼30 nm in diameter) which were then deposited on a glass substrate by dip-coating. Thermal treatment was then used to remove any organic components, leading to the production of mono- and bilayer structures as observed via atomic force microscopy (AFM). Microindentation experiments revealed a lower elastic modulus in the coating versus the substrate, in spite of its fully inorganic nature. Scratch tests were then performed at increasing applied load using a custom-built sclerometer. The coating was found to delay the appearance of visually apparent scratches by reducing the degree of chipping observed during scratch development. Instead, such coatings exhibit a transition from ductile behavior directly to the abrasive regime classically observed in glass at high loads, avoiding the production of extended sub-surface cracks that normally give rise to visual damage.
Mechanical Characterization of Thin-Film Composites using the Load-Deflection Response of Multilayer Membranes - Elastic and Fracture Properties
Authors: Gaspar Joao , Ruther Patrick , Paul Oliver 
Published: June 2019

AbstractThis paper reports on the refinement of a mechanical model for the load-deflection of multilayer membranes under uniform differential pressure and on its application to the experimental extraction of material parameters. Going beyond previous results, the analytical model takes into account the mechanics of multilayers and elastic supports covering all cases between rigidly clamped to simply supported structures and enables the straightforward assessment of stress profiles within the deformed structures. A comprehensive set of long membranes made of various multilayers of silicon nitride and oxide films are fabricated and characterized. The out-of-plane deflection profile under pressure load is monitored by means of a laser profilometer. The pressure is stepped up until fracture occurs. From the stress profiles in the membrane at fracture, the brittle material strength is analyzed using Weibull statistics. The bulge setup has been fully automated for the measurement of 80 membranes per wafer. This realizes, for the first time, the high throughput-acquisition of mechanical thin film data with convincing statistical control.
Optimizing Nonlinear Properties of Thermal Sprayed Coatings through Processing Parameters
Authors: Liu Yajie , Nakamura Toshio , Srinivasan Vasudevan , Gouldstone Andrew , Sampath Sanjay 
Published: June 2019

AbstractLow-temperature thermal cycling of plasma sprayed zirconia coatings via curvature measurements is used to quantify their nonlinear mechanical behavior. The nonlinear feature arises from the unique layered, porous and cracked morphology of thermal sprayed ceramic materials. With this procedure, various specimens were tested to investigate the effects of processing condition. The measured nonlinear properties are interpreted in the context of microstructural changes in the plasma sprayed coatings due to differences in particle state upon impact and coating build-up. The implications of this study are significant for thermo-mechanical design of strain-tolerant ceramic coatings in thermal barrier applications.
Foaming of Miscible and Immiscible Polymer Blends
Authors: Ruckdaeschel Holger , Rausch Julius , Sandler Jan K.W. , Altstaedt Volker , Schmalz Holger , Mueller Axel H.E. 
Published: June 2019

AbstractBatch-foaming of miscible, immiscible and compatibilized polymer blend systems over a wide compositional range was carried out using carbon dioxide as a physical blowing agent. The resulting foam morphology was characterized by a detailed evaluation of foam density as well as of the cellular parameters. With regard to multiphase blends, transmission electron microscopic observations further provided a detailed insight into the cell wall morphology. The role of the melt-elongational properties and of the glass transition behavior of the various blend systems on the foaming characteristics was systematically elucidated. While the miscible blends showed a simple additivity behavior with regard to their foaming characteristics and properties, a significant influence of the initial blend morphology is demonstrated for the multiphase blends.
Interface Conditions for Coupled Atomistic and Continuum Models of Solids for Dynamics Problems at Finite Temperature
Authors: Li Xiantao , E Weinan 
Published: June 2019

AbstractWe will present a general formalism for deriving boundary conditions for molecular dynamics simulations of crystalline solids in the context of atomistic/continuum coupling. These boundary conditions are modeled by generalized Langevin equations, derived from Mori-Zwanzig's formalism. Such boundary conditions are useful in suppressing phonon reflections, and maintaining the system temperature.
Multiscale Modeling of Frictional Behavior of Highly-Ordered Carbon Nanotube/Ceramic Nanocomposites
Authors: Xia Zhenhai , Curtin William A , Guduru Pradeep 
Published: June 2019

AbstractMicromechanics model incorporating with molecular dynamics (MD) simulation is developed to simulate the frictional behavior of carbon nanotube (CNT) arrays in ceramic nanocomposites. MD model is used to compute the interaction force and simulate failure mechanisms of individual nanotube at atomic length scale. The force and deformation calculated from MD simulation are passed to the continuum model to simulate the interaction between nanotube arrays and AFM tips. The coefficient of friction is determined at different load levels. The simulation shows that the low friction in the thick-wall CNT systems occurs because the stiffer CNTs are more resistant to collapse under the applied loads. The predictions for the coefficient of friction are consistent with nanoscale tests.
Synthesis and Characterization of Nitrides of Iridium and Palladium
Authors: Crowhurst Jonathan , Goncharov Alexander , Sadigh Babak , Zaug Joseph , Meng Yue , Prakapenka Vitali 
Published: June 2019

AbstractWe describe the synthesis of nitrides of iridium and palladium using the laser-heated diamond anvil cell. We have used the in-situ techniques of x-ray powder diffraction and Raman scattering to characterize these compounds and have compared our experimental findings where possible to the results of first-principles theoretical calculations. We suggest that palladium nitride is isostructural with pyrite while iridium nitride has a monoclinic symmetry and may be isostructural with baddeleyite.
Tape Casting Technique for Fabrication of Graded-Density Impactors for Tailored Dynamic Compression
Authors: Martin L. Peter , Nguyen Jeffrey H. , Patterson Jeremy R. , Orlikowski Daniel , Asoka-Kumar Palakkal P. , Holmes Neil C. 
Published: June 2019

AbstractRecently, the use of graded density impactors for dynamic compression experiments has received increasing interest. These gas gun experiments have demonstrated complex loading paths which can last microseconds, and may be capable of bridging the timescales of existing static and dynamic compression experiments. A tape casting technique has been developed for fabrication of the impactors. In the technique, a series of tapes were prepared in the Mg-Cu system with compositions ranging from 100% Mg to 100% Cu. The tapes were characterized for their layer thickness, density, and sound wave velocity. Impactors were fabricated by punching individual layers from the tapes, stacking and laminating them, removing the organic matrix, and hot-pressing the laminated structure. The density profile is determined by the order in which the tapes are stacked in the laminate and is therefore highly flexible. The resultant thickness and average density of the impactors is consistent with the data for the individual layers. Impactors were characterized for uniformity by ultrasonic C-scan and white light interferometry. Dynamic compression experiments were performed on a two-stage helium gas gun using the graded density impactors. Results will be presented and shown to agree well with hydrocode modeling.
High Pressure and High Temperature Induced Polymeric C60 Nanorods and Their Photoluminescence Properties
Authors: Liu Bingbing , Hou Yuanyuan , Wang Lin , Zou Guangtian , Iwasiewicz Agnieszka , Sundqvist Bertil 
Published: June 2019

AbstractWe report that C60 nanorods of three polymeric phases have been synthesized under high pressure and high temperature and that the photoluminescence properties of these polymeric nanorods also have been studied. C60 nanorods were fabricated by a facile solution evaporation method. Raman spectra indicate that this material transformed into orthorhombic, tetragonal and rhombohedral polymeric phases under various high pressure and high temperature conditions. SEM measurements show that the shape of the nanorods can be kept under quasi-hydrostatic pressure condition. The photoluminescence intensity of the polymeric C60 nanorods has been enhanced compared with that of the pristine C60 nanorods. The main fluorescence band shifted from 1.70 eV in the monomeric phase to near infrared in the polymeric phase when pressure and temperature were increased. The enhanced fluorescence with adjustable frequency for different polymeric C60 nanorods makes possible potential application in luminescent nanomaterials.