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NANOPARTICLES, MAGNETIC fields, FUEL cells, ELECTRICAL energy, CONDENSED matter, and SPHEROMAKS

The theory of motion of quantum electromechanical plasmoid nanobots in a condensed-state medium is presented. The mechanism of a nanobot functioning is shown to be related to the quantum exchange between a nanoparticle and the quantum-field condensed-state system realized by a tangled ( e e)-plasmoid pair. The operation of an ( e e)-plasmoid is interpreted as a quantum analog of a fuel cell based on the nanoelectromechanical systems (NEMS) of a nanobot. It is the electrical and magnetic fields of force of the ( e e)-plasmoid which control the quantum motion of the NEMS-based nanobot. This ensures its response to an external action and allows the respective physical tools to be designed in order to control self-motion of the NEMS-based nanobot in a material medium. Two available mechanisms of the relaxational self-motion of a nanobot in the condensed matter are shown: conversion of the internal quantum-mechanical energy of the nanobot into the electrical energy of a quantum ( e e)-plasmoid and conversion of the electrical energy of a quantum ( e e)-plasmoid into the mechanical energy of the nanobot's motion in a material. These mechanisms prescribe a discrete manipulation of the NEMS-based nanobot in a material medium. The time, displacement, forces and power involved in the NEMS-based nanobot transportation are estimated. [ABSTRACT FROM AUTHOR]

Geology, Géologie, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Matériaux composites, Composites, Constante élasticité, Elastic constant, Constante elasticidad, Dureté, Hardness, Dureza, Effet dimensionnel, Size effect, Efecto dimensional, Fluage, Creep, Fluencia, Forme géométrique, Geometrical shape, Forma geométrica, Graphène, Graphene, Matière charge, Filler, Materia carga, Matériau renforcé dispersion, Dispersion reinforced material, Material renforzado dispersión, Microstructure, Microestructura, Nanocomposite, Nanocompuesto, Nanoindentation, Nanoindentacion, Nanoparticule, Nanoparticle, Nanopartícula, Nanostructure, Nanoestructura, Nanotube carbone, Carbon nanotubes, Particule sphérique, Spherical particle, Partícula esférica, Polymère, Polymer, Polímero, Relation structure propriété, Property structure relationship, and Relación estructura propiedad

This article reviews recent literature on polymer nanocomposites using advanced indentation techniques to evaluate the surface mechanical properties down to the nanoscale level. Special emphasis is placed on nanocomposites incorporating carbon-based (nanotubes, graphene, nanodiamond) or inorganic (nanoclays, spherical nanoparticles) nanofillers. The current literature on instrumented indentation provides apparently conflicting information on the synergistic effect of polymer nanocomposites on mechanical properties. An effort has been done to gather information from different sources to offer a clear picture of the state-of-the-art in the field. Nanoindentation is a most valuable tool for the evaluation of the modulus, hardness and creep enhancements upon incorporation of the filler. It is shown that thermoset, glassy and semicrystalline matrices can exhibit distinct reinforcing mechanisms. The improvement of mechanical properties is found to mainly depend on the nature of the filler and the dispersion and interaction with the matrix. Other factors such as shape, dimensions and degree of orientation of the nanofiller, as well as matrix morphology are discussed. A comparison between nanoindentation results and macroscopic properties is offered. Finally, indentation size effects are also critically examined. Challenges and future perspectives in the application of depth-sensing instrumentation to characterize mechanical properties of polymer nanocomposite materials are suggested.

Geology, Géologie, Mechanics acoustics, Mécanique et acoustique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Electronique, Electronics, Electronique des semiconducteurs. Microélectronique. Optoélectronique. Dispositifs à l'état solide, Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices, Fabrication microélectronique (technologie des matériaux et des surfaces), Microelectronic fabrication (materials and surfaces technology), Metaux. Metallurgie, Metals. Metallurgy, Assemblage et découpage thermique: aspects métallurgiques, Joining, thermal cutting: metallurgical aspects, Brasage, Brazing. Soldering, Aimantation, Magnetization, Imanación, Magnetisieren, Argent alliage, Silver alloy, Plata aleación, Silberlegierung, Brasage avec refusion, Reflow soldering, Soldeo con refusión, Aufschmelzloeten, Calorimétrie différentielle balayage, Differential scanning calorimetry, Análisis calorimétrico barrido exploración, Differentialrasterkalorimetrie, Cobalt alliage, Cobalt alloy, Cobalto aleación, Cobaltlegierung, Cuivre alliage, Copper alloy, Cobre aleación, Kupferlegierung, Effet champ magnétique, Magnetic field effect, Efecto campo magnético, Magnetischer Feldeffekt, Etain alliage, Tin alloy, Estaño aleación, Zinnlegierung, Fabrication microélectronique, Microelectronic fabrication, Fabricación microeléctrica, Fer alliage, Iron alloy, Hierro aleación, Eisenlegierung, Fiabilité, Reliability, Fiabilidad, Zuverlaessigkeit, Matériau composite, Composite material, Material compuesto, Verbundwerkstoff, Métal transition alliage, Transition metal alloy, Metal transición aleación, Uebergangsmetallegierung, Nanomatériau magnétique, Magnetic nanomaterial, Nanomaterial magnético, Nanoparticule, Nanoparticle, Nanopartícula, Packaging électronique, Electronic packaging, Packaging electrónico, Particule magnétique, Magnetic particles, Perte magnétique, Iron loss, Pérdida magnética, Magnetischer Verlust, Propriété thermomécanique, Thermomechanical properties, Propriedad termomecánica, Brasure sans plomb, and Lead free solder

Sn-Ag-Cu (SAC) alloys are regarded as the most promising alternative for traditional Pb-Sn solders used in electronic packaging applications. However, the higher reflow temperature requirement, possible intermetallic formation, and reliability issues of SAC alloys generate several key challenges for successful adoption of Pb-free solder for next generation electronic packaging needs. Localized heating in interconnects can alleviate thermal stresses by preventing subjection of entire package to the higher reflow temperatures associated with the SAC solders. It had been demonstrated that SAC solder-FeCo magnetic nanoparticles (MNPs) composite paste can be reflowed locally with AC magnetic fields, enabling interconnect formation in area array packages while minimizing eddy current heating in the printed circuit board. Solder/magnetic nanocomposite pastes with varying MNP concentration were reflowed using AC magnetic fields. Differential scanning calorimetry results show a reduced undercooling of the composite pastes with the addition of MNPs. TEM results show that the FeCo MNPs are distributed in Sn matrix of the reflowed solder composites. Optical and SEM micrographs show a decrease in Sn dendrite regions as well as smaller and more homogeneous dispersed Ag3Sn with the addition of MNPs. The MNPs promote Sn solidification by providing more heterogeneous nucleation sites at relatively low undercoolings. The mechanical properties were measured by nanoindentation. The modulus, hardness, and creep resistance, increase with the MNP concentration. The enhanced mechanical properties are attributed to grain boundary and dispersion strengthening. The reflow of solder composites have been modeled based on eddy current power loss in the substrate and magnetic power losses in the solder bumps. Induction reflow of pure solder bumps (<300 μm) in an area array package using 500 Oe magnetic field at 300 kHz requires excessive eddy current power loss in the substrate, resulting in extreme temperatures that lead to blistering and delamination of the substrate. Solder-MNP composites with modest MNP loading showed temperature increases sufficient to achieve solder reflow when subjected to the same AC magnetic fields. Thermomechanical behavior of a solder joint was also modeled under cyclic temperature variations. The stress and strain are highly localized at the interface between solder and substrate. Plastic work accumulated per cycle can be used for lifetime prediction. In this article we review lead-containing and lead-free solder systems, and the electronic packaging technologies pertinent to soldering process. Recent research on the effects of MNPs on localized heating, microstructure evolution, mechanical properties, and thermomechanical reliability are summarized.

Electronics, Electronique, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Nanomatériaux et nanostructures : fabrication et caractèrisation, Nanoscale materials and structures: fabrication and characterization, Nanopoudres, Nanopowders, Méthodes de nanofabrication, Methods of nanofabrication, Méthodes de synthèse chimique, Chemical synthesis methods, Sciences appliquees, Applied sciences, Energie, Energy, Energie naturelle, Natural energy, Energie solaire, Solar energy, Conversion photovoltaïque, Photovoltaic conversion, Cellules solaires. Cellules photoélectrochimiques, Solar cells. Photoelectrochemical cells, Aire superficielle, Surface area, Area superficial, Caractéristique courant tension, Voltage current curve, Característica corriente tensión, Cellule solaire à colorant, Dye-sensitized solar cell, Célula solar sensibilizada tinte, Colorant, Dyes, Colorante, Courant court circuit, Short circuit currents, Densité courant, Current density, Densidad corriente, Diffraction RX, X ray diffraction, Difracción RX, Eclairement, Illumination, Alumbrado, Effet photovoltaïque, Photovoltaic effect, Efecto fotovoltaico, Evaluation performance, Performance evaluation, Evaluación prestación, Facteur remplissage, Fill factor, Matériau cristallin, Crystalline material, Material cristalino, Modulation amplitude, Amplitude modulation, Modulación amplitud, Méthode hydrothermale, Hydrothermal growth, Método hidrotermal, Nanoparticule, Nanoparticle, Nanopartícula, Photoanode, Photoanodes, Spectrométrie impédance électrochimique, Electrochemical impedance spectroscopy, Stannate, Stannates, Estannato, Synthèse hydrothermale, Hydrothermal synthesis, Taux conversion, Conversion rate, Factor conversión, Temps réaction, Reaction time, Tiempo reacción, Tension circuit ouvert, Open circuit voltage, Zinc, 8116B, Dye sensitized solar cells, Nanoflowers, X-ray diffraction, and Zinc stannate

Ternary zinc stannate (Zn2SnO4) nanoparticles were synthesized using the green hydrothermal technique at 200 °C for different reaction times and they were used as photoanodes for dye sensitized solar cells (DSSCs). The photovoltaic performance of the DSSC cells was characterized by measuring the J-V curves in dark, and under illumination. Among the three DSSC cells, the photoanode based on Zn2SnO4 nanoflower synthesized at 200 °C for 48 h recorded the highest conversion efficiency of 3.346% under 1 sun illumination (AM 1.5 G, 100 mW cm-2) with improved short-circuit current density of 7,859 mA cm-2, and comparable open-circuit photovoltage (0.626 V) and fill factor (0.679). This enhancement of characteristics is primarily attributed to the higher current density owing to its better crystalline quality as well as the larger surface area of Zn2SnO4 nanoflowers, all of which are the results of longer reaction time. The findings are further substantiated by means of open-circuit photovoltage decay experiment, dye loading behavior and electrochemical impedance spectroscopy.

General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Condensed state physics, Physique de l'état condensé, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Diffusion(transport), Diffusion, Etat adsorbé, Adsorbed state, Estado adsorbido, Microscopie tunnel balayage, Scanning tunneling microscopy, Métal transition, Transition elements, Méthode fonctionnelle densité, Density functional method, Platine, Platinum, Pt, Aromatic adsorbates, Density functional theory, and Van der Waals

We present a combined density functional theory (DFT) and scanning tunneling microscopy (STM) investigation of the adsorption and diffusion of non-interacting 2,2,2-trifluoroacetophenone (TFAP) and (R)-(+)-1-(1-naphthyl)ethylamine ((R)-NEA) on the Pt(111) surface. The two adsorbates are prochiral and chiral, respectively, and their surface diffusion is of specific interest in relation to chirality transfer from chiral modifiers to prochiral reactants in Orito-type hydrogenation on metal catalysts. Using a van der Waals-DFT description, the two adsorbates are shown to bind strongly to the surface through the aromatic groups and their respective side groups with carbonyl and amine functions. Adsorption energies were calculated for twelve different (R)-NEA adsorption conformers. A naming convention is introduced to describe the different conformers, and the two most stable ones are labeled (R)-NEA-1 and (R)-NEA-2. Diffusion of both adsorbates is calculated to proceed in a walking manner, moving either the aromatic group or the substituent group. For TFAP a diffusion barrier of 0.66 eV is calculated while 0.74-0.89 eV barriers are found for the two adsorption conformers of (R)-NEA. In agreement with the computed results, the room temperature STM study shows rapid diffusion of TFAP and significantly slower diffusion of (R)-NEA. Whereas TFAP monomers are rarely imaged at room temperature, consistent with rapid diffusion, time-lapsed images of (R)-NEA show limited molecular motion in localized regions of the surface. Furthermore, the motion of (R)-NEA is strongly conformation dependent. (R)-NEA-1 displays a much greater propensity to undergo rotational motion. The STM data for (R)-NEA are compared with DFT calculated energy barriers for translation and rotation. The possible implications of the experimental and calculated data for a role for induced fit stereodirection by (R)-NEA/Pt(111) are commented on.

Crystallography, Cristallographie cristallogenèse, Electronics, Electronique, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Supraconductivité, Superconductivity, Couches supraconductrices et structures de basse dimensionnalité, Superconducting films and low-dimensional structures, Systèmes mésoscopiques et nanostructures, Mesoscopic and nanoscale systems, Anisotropie, Anisotropy, Effet tunnel, Tunnel effect, Etat lié, Bound state, Supraconductivité, Superconductivity, 7478N, Andreev bound states, Gapless edge states, Topological superconductors, and Tunneling spectroscopy

Tunneling conductance spectra of normal metal/insulator/superconductor (N/I/S) junctions are calculated to determine the potential of tunneling spectroscopy in investigations of topological superconductivity. Peculiar feature of topological superconductors is the formation of gapless edge states in them. Since the conductance of N/I/S junctions is sensitive to the formation of these edge states, topological superconductivity can be identified through edge-state detection. Herein, the effects of Fermi surface anisotropy and an applied magnetic field on the conductance spectra are analyzed to gather indications that can help to identify the topological nature of actual materials.

Crystallography, Cristallographie cristallogenèse, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Surfaces et interfaces; couches minces et trichites (structure et propriétés non électroniques), Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties), Structure et morphologie de couches minces, Thin film structure and morphology, Structure et morphologie; épaisseur, Structure and morphology; thickness, Propriétés physiques non électroniques de couches minces, Physical properties of thin films, nonelectronic, Propriétés mécaniques et acoustiques, Mechanical and acoustical properties, Acier inoxydable 316L, Stainless steel-316L, Adhérence, Adhesion, Alliage base nickel, Nickel base alloys, Article synthèse, Reviews, Couche mince amorphe, Amorphous thin film, Capa fina amorfa, Couche mince métallique, Metallic thin films, Couche mince, Thin films, Durée vie, Lifetime, Déformation, Deformation, Epaisseur couche, Layer thickness, Espesor capa, Etude expérimentale, Experimental study, Etude théorique, Theoretical study, Flexion, Bending, Instabilité, Instability, Matériau revêtu, Coated material, Material revestido, Méthode élément fini, Finite element method, Propriété mécanique, Mechanical properties, Revêtement, Coatings, Résistance corrosion, Corrosion resistance, Simulation numérique, Digital simulation, Tribologie, Tribology, Verre métallique, Metallic glasses, 4335N, 6855J, 6860B, Substrat verre, Coating, Fatigue lifetime, Fatigue-crack initiation, Finite-element model, and Thin-film metallic glass (TFMG)

Amorphous metallic films, a thin form of metallic glasses, have been attracting more and more attentions in the last two decades, due to their unique properties, compared with the conventional crystalline films, such as high strength, high toughness, large elastic limits, and high-corrosion resistance. However, the deformation mechanisms of thin-film metallic glasses (TFMGs) are still far from in-depth understanding, although some of their properties and characteristics are not as good as metallic or ceramic films. This paper will focus on reviewing and discussing the fatigue behavior of structural-material substrates coated with TFMGs. The substrates include 316L stainless steel, Al-based, Ni-based, Zr-based, and Ti-based alloys. The results show that the four-point-bending fatigue life of the substrates is greatly improved by Zr- and Cu-based TFMGs, while Fe-based TFMG, TiN, and pure-Cu films are not so beneficial in extending the fatigue life of 316L stainless steel. In comparison, the tension-tension fatigue lifetime and endurance limit of 316L stainless steel cannot be improved by the Zr- and Cu-based TFMGs. However, the TFMGs annealed at a temperature within the supercooled liquid region (ΔT) can further improve the fatigue behavior, compared to as-deposited TFMGs. The fatigue mechanisms of crystalline and bulk metallic glass (BMG) materials, together with TFMGs, are reviewed in the present work. Crystals and BMGs present 3-stage and 4-stage fatigue-deformation mechanisms, respectively. The fatigue life of medium-strength structural materials tends to be significantly improved by TFMGs. A synergistic experimental/theoretical study has shown the micro-mechanisms of the fatigue behavior of TFMGs adhered to substrates, as well as film-adhesion and thickness effects on fatigue behavior of the substrate. Furthermore, shear-band initiation and propagation under bending deformation are investigated using the Rudnicki-Rice instability theory and the free-volume models employing finite-element simulations.

Crystallography, Cristallographie cristallogenèse, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Surfaces et interfaces; couches minces et trichites (structure et propriétés non électroniques), Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties), Surfaces solides et interfaces solide-solide, Solid surfaces and solid-solid interfaces, Diffusion; formation d'interfaces, Diffusion; interface formation, Structure et morphologie de couches minces, Thin film structure and morphology, Structure et morphologie; épaisseur, Structure and morphology; thickness, Trichites et dendrites (croissance, structure et propriétés non électroniques), Whiskers and dendrites (growth, structure, and nonelectronic properties), Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Méthodes de dépôt de films et de revêtements; croissance de films et épitaxie, Methods of deposition of films and coatings; film growth and epitaxy, Théorie et modèles de la croissance de films, Theory and models of film growth, Composé intermétallique, Intermetallic compounds, Couche mince métallique, Metallic thin films, Couche épaisse, Thick films, Diffusion(transport), Diffusion, Défaut cristallin, Crystal defects, Joint grain, Grain boundaries, Mécanisme croissance, Growth mechanism, Mecanismo crecimiento, Packaging électronique, Electronic packaging, Packaging electrónico, Polycristal, Polycrystals, Trichite, Whiskers, Verre, Glass, 6835F, 6855A, 6855J, Electronic Packaging, Intermetallic Compound, Thin Film Metallic Glass, Tin Whiskers, and Underlayer

Introduction of underlayer is one of the mitigation methods commonly used for the suppression of the Sn whiskering phenomenon in electronic packaging. The presence of a proper underlayer prevents the intermetallic compound formation resulting from a Cu/Sn interaction believed to be the major driving force of Sn whisker growth. Ni as an underlayer has been widely studied and industrially accepted. However, Ni underlayer suffers from its polycrystalline grain structure where grain boundaries can potentially act as a diffusion path for the Cu/Sn interaction to take place. In this study, a 100-nm-thick Zr46Ti26Ni28 thin film metallic glass (TFMG) is introduced to block the Cu/Sn interaction. Samples with and without TFMG underlayer were aged at room temperature for up to 33 days in ambient atmosphere. No Sn whisker is observed in the sample with TFMG underlayer after aging. In contrast, Sn whiskers are found in the absence of the underlayer and the whisker density increases with increasing aging time. It is found that TFMG underlayer plays an important role in effectively suppressing Sn whisker growth.