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PERMITTIVITY, DIELECTRIC loss, POLYMETHYLMETHACRYLATE, BISMUTH compounds, FERRITES, ELECTRIC conductivity, PASSIVATION, and SURFACE preparation

Abstract: Surface modification plays an important role to enhance the dielectric constant and minimize the dielectric loss. In this study, poly(methyl methacrylate) (PMMA) composites filled with 2-aminoethanesulfonic acid-modified bismuth ferrite (BiFeO3; BFO) have been prepared via solution casting technique. The surface morphology of the composites provides a better homogeneous dispersion of the particles in the polymer matrix and increases interface compatibility between modified BFO and PMMA matrix. The experimental results show that the composites have high dielectric constant (≈ 147), alternating current (AC) conductivity (1 × 10−5) and relatively low loss (< 1) at 100 Hz. The percolation phenomenon is well observed in the composite having less than 30 wt.% of BFO particles. Further, the composites produce passivation layers on the surface of modified BFO particles which might improve the morphology and promote the space charges, interface effects and dielectric properties. Our strategy is to provide a simple and efficient approach to fabricate high-performance dielectric composites for energy storage applications.Graphical Abstract: [ABSTRACT FROM AUTHOR]

Crystallography, Cristallographie cristallogenèse, Electronics, Electronique, 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 electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Propriétés et matériaux magnétiques, Magnetic properties and materials, Etudes de matériaux magnétiques particuliers, Studies of specific magnetic materials, Aimants permanents, Permanent magnets, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Méthodes de croissance cristalline; physique de la croissance cristalline, Methods of crystal growth; physics of crystal growth, Théorie et modèles de la croissance cristalline; physique de la croissance cristalline, morphologie cristalline et orientation cristalline, Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation, Méthodes de dépôt de films et de revêtements; croissance de films et épitaxie, Methods of deposition of films and coatings; film growth and epitaxy, Techniques de revêtement par pulvérisation, Spray coating techniques, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Aimant permanent, Permanent magnet, Imán permanente, Dauermagnet, Aimantation saturation, Saturation magnetization, Imanación saturación, Calcination, Calcining, Calcinación, Kalzinieren, Champ extérieur, External field, Campo exterior, Commande dimension, Size control, Dimension particule, Particle size, Dimensión partícula, Teilchengroesse, Distribution dimension particule, Particle size distribution, Distribución dimensión partícula, Dépôt projection, Spray coating, Depósito proyección, Spritzbeschichten, Effet champ magnétique, Magnetic field effect, Efecto campo magnético, Magnetischer Feldeffekt, Effet température, Temperature effect, Efecto temperatura, Temperatureinfluss, Force coercitive, Coercive force, Haute performance, High performance, Alto rendimiento, Mécanisme croissance, Growth mechanism, Mecanismo crecimiento, Wachstumsmechanismus, Nanostructure, Nanoestructura, Propriété magnétique, Magnetic properties, Propiedad magnética, Magnetische Eigenschaft, 7550W, 8110A, 8115R, NaCl, Pyrolyse par projection ultrasonique, Ultrasonic spray pyrolysis, Pyrolyse par projection, Spray pyrolysis, SrFe12O19, Hexaferrite, high coercivity, magnetic alignment, particle size control, salt assisted, and spray pyrolysis

Strontium hexaferrite (SrFe12O19, SrM) suitable for high-performance permanent magnet applications was synthesized by salt-assisted ultrasonic spray pyrolysis (SA-USP) and subsequent calcination. To control the particle size, the intermediate phase of SrM was collected by SA-USP and various sizes of SrM were obtained by calcining the as-prepared sample at temperatures ranging from 800°C to 1050°C. The synthesized SrM was magnetically aligned by using an external magnetic field to improve remanence. The synthesized particles were of nano- to submicron scale and nonagglomerated. The magnetic properties and squareness of the material depended on the particle size and distribution. Additionally, the NaCl added during synthesis facilitated the formation of nonagglomerated particles, while enhancing and controlling particle growth. The optimum magnetic properties were achieved at calcination temperature of 1000°C, resulting in coercivity of 5646 Oe, saturation magnetization of 73.3 emu/g, and remanence of 59.1 emu/g (80.6% of Ms).

Crystallography, Cristallographie cristallogenèse, Electronics, Electronique, Metallurgy, welding, Métallurgie, soudage, 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, Diagrammes de phases et microstructures développées par solidification et par transformations de phases solide-solide, Phase diagrams and microstructures developed by solidification and solid-solid phase transformations, Solidification, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Assemblage et découpage thermique: aspects métallurgiques, Joining, thermal cutting: metallurgical aspects, Brasage, Brazing. Soldering, Assemblage brasage tendre, Soldered joints, Brasage tendre, Soldering, Calorimétrie différentielle balayage, Differential scanning calorimetry, Chaleur latente, Latent heat, Etat fondu, Melts, Fusion, Melting, Revêtement surface, Surface coating, Solidification, Surfusion, Supercooling, Traitement surface, Surface treatments, 8130F, Brasure, Solder, DSC, Sn-based solders, Undercooling, and recalescence

Undercooling and recalescence were studied using the differential scanning calorimetry (DSC) method on real electronic systems. Two solder pastes, Sn62.5Pb36.5Ag1 and Sn96.5Ag3Cu0.5, were used for preparation of electronic joints. Various combinations of these solders and soldering pads with different surface finishes such as Cu, Cu-Ni-Au, Cu-Sn, and Cu-Sn99Cu1 were used. During melting of both pastes, the Sn and Sn99Cu1 surface finishes immediately dissolved in the solder and the Cu surface coating was exposed to the melt. Therefore, practically the same undercooling was found for the Cu, Cu-Sn, and Cu-Sn99Cu1 coatings. The lowest undercooling was found for the Cu-Ni-Au surface finish for both solder pastes. If two separated electronic joints were made on the sample, two separate peaks were found in the DSC signal during solidification. In the sample with only one joint, only one exothermic peak was found. These findings were observed for all paste/surface finish combinations. These data were analyzed, showing that this effect is a consequence of undercooling and recalescence: Latent heat released during solidification of the joint increases the surrounding temperature and influences all the processes taking place.

Crystallography, Cristallographie cristallogenèse, Electronics, Electronique, Metallurgy, welding, Métallurgie, soudage, 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, Méthodes de croissance cristalline; physique de la croissance cristalline, Methods of crystal growth; physics of crystal growth, Théorie et modèles de la croissance cristalline; physique de la croissance cristalline, morphologie cristalline et orientation cristalline, Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation, Méthodes de nanofabrication, Methods of nanofabrication, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Assemblage et découpage thermique: aspects métallurgiques, Joining, thermal cutting: metallurgical aspects, Brasage, Brazing. Soldering, Assemblage brasage tendre, Soldered joint, Junta soldada, Weichloetverbindung, Carte électronique, Printed circuit board, Tarjeta electronica, Circuit ET, AND circuit, Circuito Y, Composé intermétallique, Intermetallic compound, Compuesto intermetálico, Intermetallische Verbindung, Conductivité électrique, Electrical conductivity, Conductividad eléctrica, Elektrische Leitfaehigkeit, Couche barrière, Barrier layer, Diffusion(transport), Diffusion, Essai cisaillement, Shear test, Ensayo cortante, Scherpruefung, Etude comparative, Comparative study, Estudio comparativo, Vergleich, Haute température, High temperature, Alta temperatura, Hochtemperatur, Immersion, Inmersión, Eintauchen, Impression, Printing, Impresión, Interface, Interfase, Grenzflaeche, Microstructure, Microestructura, Mikrogefuege, Morphologie, Morphology, Morfología, Mécanisme croissance, Growth mechanism, Mecanismo crecimiento, Wachstumsmechanismus, Nickel, Niquel, Palladium, Paladio, Réaction interface, Interface reaction, Reacción interfase, Résistivité électrique, Electric resistivity, Resistividad eléctrica, Solubilité, Solubility, Solubilidad, Loeslichkeit, Synthèse nanomatériau, Nanomaterial synthesis, Síntesis nanomaterial, Technologie BGA, BGA technology, Tecnología BGA, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, 8110A, Brasure, Solder, Substrat composé organique, Substrat or, BGA, ENEPIG, Interfacial reaction, pad size, and stencil printing

In this work, solder balls in ball grid array packaging technology with the pitch of 300 μm were fabricated by stencil printing solder paste and then reflowed at high temperature. In order to evaluate the quality of solder ball after printing and reflowing processes, the mechanical performance of the joint between the solder balls and the pad was measured by shear test and the electrical resistance was tested after assembly of the substrate and printed circuit board. A comparative study of pad size on the interfacial reaction between solder paste and surface finish of electroless nickel-electroless palladium-immersion gold on the organic substrate was performed and then analyzed by observing the microstructure at the interface. Large discontinuous (Cu,Ni)6Sn5 was found at the interface of the solder with the pad size of 120 μm, while spalled (Pd,Ni)Sn4 and thin (Cu,Ni)6Sn5 layer appeared for a pad size of 140 μm. The IMC (intermetallic compounds) was determined by the residual Cu concentration, the Pd concentration in the solder, and the Ni2SnP barrier layer morphology at the interface, which were significantly influenced by the pad size. A reaction model during the reflow was proposed to illustrate the growth of the IMC and the relationship between the IMC and the pad size. With Pd concentration higher than the solubility of Pd in the solder, spalled (Pd,Ni)Sn4 took shape along the interface. The solubility of Pd was influenced by Ni concentration; however, the Ni diffusion from the substrate was largely dependent on the barrier layer Ni2SnP. Furthermore, the Ni diffusion also impacted the growth and morphology of (Cu,Ni)6Sn5, which was not only limited by the Cu concentration.

Crystallography, Cristallographie cristallogenèse, Electronics, Electronique, 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, Structure des liquides et des solides; cristallographie, Structure of solids and liquids; crystallography, Etat cristallin (incluant les mouvements moléculaires dans les solides), Crystalline state (including molecular motions in solids), Théorie de la structure cristalline, symétrie cristalline; calculs et modélisation, Theory of crystal structure, crystal symmetry; calculations and modeling, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Propriétés optiques, spectroscopie et autres interactions de la matière condensée avec les particules et le rayonnement, Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation, Propriétés optiques des matériaux massifs et des couches minces, Optical properties of bulk materials and thin films, Sciences appliquees, Applied sciences, Electronique, Electronics, Electronique des semiconducteurs. Microélectronique. Optoélectronique. Dispositifs à l'état solide, Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices, Dispositifs optoélectroniques, Optoelectronic devices, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Addition europium, Europium addition, Adicion europio, Europiumzusatz, Agent surface anionique, Anionic surfactant, Agente superficie aniónico, Agent surface, Surfactant, Agente superficie, Oberflaechenaktiver Stoff, Composé du sodium, Sodium compound, Sodio compuesto, Natriumverbindung, Coprécipitation, Coprecipitation, Coprecipitación, Cristallinité, Crystallinity, Cristalinidad, Diode électroluminescente, Light emitting diode, Diodo electroluminescente, Déplacement raie, Spectral line shift, Desplazamiento raya espectral, Déplacement vers le rouge, Redshift, Desplazamiento hacia el rojo, Luminescence, Luminiscencia, Lumineszenz, Matériau luminescent, Luminescent material, Material luminescente, Phosphate, Phosphates, Fosfato, Phosphat, Photoluminescence, Fotoluminiscencia, Propriété optique, Optical properties, Propiedad óptica, Optische Eigenschaft, Propriété symétrie, Symmetry property, Propiedad simetría, Rayonnement UV, Ultraviolet radiation, Radiación ultravioleta, Ultraviolettstrahlen, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Transfert charge, Charge transfer, Transferencia carga, 6150A, 8560J, H3PO4, LaPO4, Phosphor, coprecipitation, surface modification, and surfactant

The luminescence of LaPO4:Eu phosphors was improved by coprecipitation with phosphate from different sources and with anionic surfactants. The effects of the method of synthesis on the characteristics of the phosphors were investigated. When H3PO4 was used as the source of phosphate, strong absorption of the charge transfer band (CTB) was observed. A red shift of the CTB absorption was observed when (NH4)2HPO4 and Na5P3O1O were used as sources of phosphate. Phosphors with high crystallographic symmetry of Eu3+ in the lattice were synthesized when (NH4)2HPO4 was used. The optimum crystallinity and the maximum photoluminescence (PL) intensity were obtained when the phosphor surface was modified with 1 mol.% (NaPO3)6 and 3 mol.% sodium dodecyl sulfate (SDS) surfactant, with PL intensity being increased by 10% and 7%, respectively.

Crystallography, Cristallographie cristallogenèse, Electronics, Electronique, 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, Equations d'état, équilibres de phases et transformations de phases, Equations of state, phase equilibria, and phase transitions, Etudes générales des transformations de phases, General studies of phase transitions, Ordre-désordre et mécanique statistique de systèmes modèles, Order-disorder and statistical mechanics of model systems, Sciences appliquees, Applied sciences, Electrotechnique. Electroenergetique, Electrical engineering. Electrical power engineering, Electroénergétique, Electrical power engineering, Conversion directe et accumulation d'énergie, Direct energy conversion and energy accumulation, Conversion électrochimique: piles et accumulateurs électrochimiques, piles à combustibles, Electrochemical conversion: primary and secondary batteries, fuel cells, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Batterie lithium, Lithium battery, Cathode, Cátodo, Kathode, Hafnium, Hafnio, Hydroxyde, Hydroxides, Hidróxido, Hydroxid, Interception(chimie), Scavenging, Métal transition, Transition metal, Metal transición, Uebergangsmetalle, Procédé sol gel, Sol gel process, Procedimiento sol gel, Propriété électrochimique, Electrochemical properties, Propiedad electroquímica, Elektrochemische Eigenschaft, Précurseur, Precursor, Relation ordre, Ordering, Relación orden, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Transfert charge, Charge transfer, Transferencia carga, Transformation ordre désordre, Order disorder transformation, Transformación desorden-orden, Ordnungsumwandlung, 6460C, 8247A, Al(OH)3, Al2O3, Layered compounds, electrochemical properties, sol-gel chemistry, and surface modifiers

In an attempt to prepare phase-pure LiCo1/3Mn1/3Ni1/3O2 compound, the sol-gel method with precursors containing different ratios of lithium and transition-metal ions such as Li:M = 1:1, 1.05:1, 1.10:1, 1.15:1, 1.20:1, and 1.25:1 has been deployed. Properties such as phase purity, perfect layeredness, good cation ordering, and acceptable charge-discharge behavior were observed only when LiCo1/3Ni1/3Mn1/3O2 was prepared using a Li:M ratio of 1.15:1.0, leading to the recommendation of this as the optimum precursor ratio to prepare active LiCo1/3Ni1/3Mn1/3O2 cathodes for batteries. Further, with a view to suppress the capacity fade behavior of native LiCo1/3Mn1/3Ni1/3O2 cathodes observed in high-voltage (4.6 V) regions, selected HF-scavenging metal oxide (Al2O3) or metal hydroxide [Al(OH)3] was deployed as a surface modifier. Interestingly, LiCo1/3Ni1/3Mn1/3O2 cathode modified with Al(OH)3 exhibited significantly improved electrochemical properties such as lower charge-transfer resistance (42 Ω), higher specific capacity (158 mAh/g), and excellent capacity retention (99%). This study demonstrates the superiority of Al(OH)3 over Al2O3 in modifying the electrochemical properties of native LiCo1/3Ni1/3Mn1/3O2 cathodes, as desired for practical lithium battery applications.

Crystallography, Cristallographie cristallogenèse, Electronics, Electronique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Assemblage et découpage thermique: aspects métallurgiques, Joining, thermal cutting: metallurgical aspects, Brasage, Brazing. Soldering, Article synthèse, Review, Artículo síntesis, Assemblage brasage tendre, Soldered joint, Junta soldada, Weichloetverbindung, Bande interdite, Energy gap, Banda prohibida, Energieluecke, Carte électronique, Printed circuit board, Tarjeta electronica, Composant électronique, Electronic component, Componente electrónico, Elektronisches Bauelement, Cuivre, Copper, Cobre, Kupfer, Fiabilité, Reliability, Fiabilidad, Zuverlaessigkeit, Fil, Thread, Hilo, Immersion, Inmersión, Eintauchen, Métallisation, Metallizing, Metalización, Nickel, Niquel, Or, Gold, Oro, Oxydation, Oxidation, Oxidación, Palladium, Paladio, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Brasure, Solder, ENEPIG, reliability, solder interconnects, and surface finishes

Surface finishes are used to protect exposed copper metallization in printed circuit boards from oxidation and to provide a solderable surface on which to mount electronic components. While it is true that some people have called electroless nickel electroless palladium immersion gold (ENEPIG) a universal finish for a wide range of applications from wire bonding to solder interconnects, this paper provides a review of the current literature on ENEPIG and assesses its overall capabilities compared to other surface finishes. Gaps in understanding the performance of ENEPIG as a printed wiring board surface finish are identified and further testing is recommended.

Crystallography, Cristallographie cristallogenèse, Electronics, Electronique, 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, Dispositifs optoélectroniques, Optoelectronic devices, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Propriétés mécaniques. Rhéologie. Mécanique de la rupture. Tribologie, Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology, Rupture, Fractures, Analyse quantitative, Quantitative analysis, Análisis cuantitativo, Quantitative Analyse, Composition chimique, Chemical composition, Composición química, Chemische Zusammensetzung, Endommagement, Damaging, Deterioración, Etalonnage, Calibration, Contraste, Kalibrieren, Faisceau ionique, Ion beam, Haz iónico, Ionenstrahl, Faisceau électronique, Electron beam, Haz electrónico, Elektronenstrahl, Interaction électronique, Electron interaction, Interacción electrónica, Photodétecteur, Photodetector, Fotodetector, Préparation surface, Surface preparation, Preparación superficie, Oberflaechenvorbereitung, Semiconducteur II-VI, II-VI semiconductors, Spectrométrie Auger, Auger electron spectrometry, Espectrometría Auger, Auger Spektrometrie, Stoechiométrie, Stoichiometry, Estequiométría, Stoechiometrie, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, 8560G, CdTe, Auger electron spectroscopy, HgCdTe, beam damage, and quantification

Auger electron spectroscopy of Hg1-xCdxTe has been investigated for quantitative analysis. HgCdTe is known to be a very sensitive material which easily suffers from ion beam and electron beam interactions. Two methods were compared for accurate and reproducible quantification of the chemical composition. The first strategy was to reduce as much as possible the damage caused by surface preparation and the effect of the incident electron beam on the material. Quantification was then achieved by use of relative sensitivity factors estimated by use of calibration reference samples. This method was rejected because of unavoidable beam damage which resulted in different chemical changes for the reference CdTe and the HgCdTe sample of interest. The second strategy was to precisely control the experimental conditions to ensure reproducible degradation. Quantification was achieved by analysis of reference HgCdTe samples with different Cd composition. Successful quantification was achieved on stoichiometric material of composition of 0.2 < XCd < 0.3 with a XCd discrimination limit of ΔXCd = 0.02 and an analysis step of 10 nm.

Crystallography, Cristallographie cristallogenèse, Electronics, Electronique, 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, Structure des liquides et des solides; cristallographie, Structure of solids and liquids; crystallography, Défauts et impuretés dans les cristaux; microstructure, Defects and impurities in crystals; microstructure, Joints de grains et joints de macle, Grain and twin boundaries, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Diagrammes de phases et microstructures développées par solidification et par transformations de phases solide-solide, Phase diagrams and microstructures developed by solidification and solid-solid phase transformations, Précipitation, Precipitation, Sciences appliquees, Applied sciences, Electronique, Electronics, Electronique des semiconducteurs. Microélectronique. Optoélectronique. Dispositifs à l'état solide, Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices, Dispositifs optoélectroniques, Optoelectronic devices, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Addition lanthane, Lanthanum additions, Bismuth, Capteur de gaz, Gas sensors, Conductivité électrique, Electrical conductivity, Couche mince, Thin films, Cristallite, Crystallites, Diffraction RX, XRD, Diffractomètre RX, X-ray diffractometers, Diode électroluminescente, Light emitting diodes, Dopage, Doping, Dopen, Défaut cristallin, Crystal defects, Dépendance température, Temperature dependence, Détecteur de gaz, Gas detector, Detector de gas, Effet concentration, Quantity ratio, Ethanol, Fonction réponse, Response functions, Joint grain, Grain boundaries, Microscopie force atomique, Atomic force microscopy, Microscopie électronique balayage, Scanning electron microscopy, Or, Gold, Phase gazeuse, Gas phase, Précipitation, Precipitation, Restauration (propriété), Recovery (properties), Restauración (propiedad), Erholung, Revêtement, Coatings, Réflexion diffuse, Diffuse reflection, Reflexión difusa, Réseau quadratique, Tetragonal lattices, Spectre réflexion, Reflection spectrum, Espectro reflexión, Vanadate, Vanadates, 6172M, 8130M, 8560J, BiVO4, Substrat verre, ethanol, film, and gas sensing

Bismuth vanadate (BiVO4) and lanthanum-doped bismuth vanadate (La-doped BiVO4) were prepared via the precipitation method. Their films were produced by simple drop-coating of the initial solutions over gold electrodes, which were coated over a glass substrate. The structural properties of BiVO4 and La-doped BiVO4 samples were studied using x-ray diffractometer, diffuse reflectance spectroscopy, scanning electron microscopy, atomic force microscopy, and compositional analysis. A chamber was designed to install the sensing device and also controllable tools for gas flow rate and temperature. Changes in the resistance of the prepared layers were recorded during exposure to various amounts of ethanol vapor at different temperatures. Both BiVO4 and La-doped BiVO4 layers showed measurable responses in the form of resistance drop (increased conductivity). The higher temperatures up to 450 °C led to stronger signals. The layer containing lanthanum showed signals with shorter recovery times. Introduction of lanthanum caused smaller crystallite sizes in addition to the formation of tetragonal phase of BiVO4. Presence of lanthanum increased the amounts of grain boundaries, magnitude of the response, and sensitivity. Sensitivity of La-doped BiVO4 was almost twice that of the BiVO4 at concentrations of 150-500 ppm of ethanol. Also, the correlation of the response as a function of concentration of ethanol in gas phase was exploited, and two different linear ranges were observed for the lower and higher concentrations.

Crystallography, Cristallographie cristallogenèse, Electronics, Electronique, Metallurgy, welding, Métallurgie, soudage, 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, Méthodes de dépôt de films et de revêtements; croissance de films et épitaxie, Methods of deposition of films and coatings; film growth and epitaxy, Dépôt par faisceau laser, Laser deposition, Sciences appliquees, Applied sciences, Electronique, Electronics, Electronique des semiconducteurs. Microélectronique. Optoélectronique. Dispositifs à l'état solide, Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices, Dispositifs optoélectroniques, Optoelectronic devices, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Addition gallium, Gallium addition, Adición galio, Galliumzusatz, Autoéchauffement, Self heating, Autocalentamiento, Coefficient absorption, Absorption coefficient, Coeficiente absorción, Composé III-V, III-V compound, Compuesto III-V, Conductivité électrique, Electrical conductivity, Conductividad eléctrica, Elektrische Leitfaehigkeit, Diode électroluminescente, Light emitting diode, Diodo electroluminescente, Dispositif optoélectronique, Optoelectronic device, Dispositivo optoelectrónico, Dépôt laser pulsé, Pulsed laser deposition, Facteur transmission, Transmittance, Factor transmisión, Transmission faktor, Laser excimère, Excimer lasers, Lumière verte, Green light, Luz verde, Méthode ablation laser, Laser ablation technique, Puissance sortie, Output power, Potencia salida, Recuit faisceau laser, Laser beam annealing, Résistance contact, Contact resistance, Resistencia contacto, Kontaktwiderstand, Semiconducteur III-V, III-V semiconductors, Source chaleur, Heat source, Fuente calor, Traitement par laser, Laser assisted processing, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, 8115F, 8560J, GaN, Substrat GaN, ZnO, I-V, light-emitting diode, and p-GaN

Ga-doped ZnO (GZO) transparent conducting oxide was grown by oxygen plasma-enhanced pulsed laser deposition. GZO grown in the presence of oxygen radicals had resistivity of 1 × 10-3 Ω cm and average visible (500-700 nm) transmittance of 92.5%. A low specific contact resistance of 6.5 × 10-4 Ω cm2 of GZO on p-GaN was achieved by excimer laser annealing (ELA) treatment of p-GaN before GZO electrode deposition. The ELA-treated light emitting diode (LED) fabricated with the GZO electrode as a current-spreading layer resulted in light-output power enhanced by 56.2% at 100 mA compared with that fabricated with a conventional Ni/Au metal electrode. The high-light output and low degradation of light-output power were attributed to the decrease in contact resistance between the p-GaN layer and the GZO electrode and uniform current spreading over the p-GaN layer. In addition, low contact resistance results in a decrease of self-heat generation during current drive.

Crystallography, Cristallographie cristallogenèse, Electronics, Electronique, 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, Propriétés mécaniques et acoustiques de l'état condensé, Mechanical and acoustical properties of condensed matter, Propriétés mécaniques des solides, Mechanical properties of solids, Elasticité, constantes d'élasticité, Elasticity, elastic constants, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Assemblage et découpage thermique: aspects métallurgiques, Joining, thermal cutting: metallurgical aspects, Brasage, Brazing. Soldering, Assemblage brasage tendre, Soldered joint, Junta soldada, Weichloetverbindung, Cisaillement, Shear, Cizalladura, Scherung, Composé intermétallique, Intermetallic compound, Compuesto intermetálico, Intermetallische Verbindung, Contrainte traction, Tensile stress, Tensión traccíon, Zugspannung, Couche interfaciale, Interfacial layer, Capa interfacial, Epaisseur, Thickness, Espesor, Dicke, Fissure interface, Interface crack, Fisura interfase, Fracture, Fractura, Immersion, Inmersión, Eintauchen, Limite élasticité, Yield strength, Límite elasticidad, Streckgrenze, Microstructure, Microestructura, Mikrogefuege, Mode rupture, Fracture mode, Modo ruptura, Morphologie, Morphology, Morfología, Métallisation, Metallizing, Metalización, Nickel, Niquel, Or, Gold, Oro, Propagation fissure, Crack propagation, Propagación fisura, Rissausbreitung, Propriété mécanique, Mechanical properties, Propiedad mecánica, Rugosité, Roughness, Rugosidad, Rauhigkeit, Rupture, Ruptura, Bruch, Résistance rupture, Rupture strength, Resistencia ruptura, Structure sandwich, Sandwich structure, Estructura sandwich, Traitement surface, Surface treatment, Tratamiento superficie, Oberflaechenbehandlung, Ténacité, Fracture toughness, Tenacidad, Bruchzaehigkeit, Vitesse déformation, Strain rate, Velocidad deformación, Verformungsgeschwindigkeit, 6220D, Brasure, Solder, SnAgCu, Substrat cuivre, ENIG surface finish, Sn-Ag solders, Solder joint fracture, fracture mechanism map, and interfacial fracture

When dropped, electronic packages often undergo failure by propagation of an interfacial crack in solder joints under a combination of tensile and shear loading. Hence, it is crucial to understand and predict the fracture behavior of solder joints under mixed-mode high-rate loading conditions. In this work, the effects of the loading conditions (strain rate and loading angle) and microstructure [interfacial intermetallic compound (IMC) morphology and solder yield strength] on the mixed-mode fracture toughness of Sn-3.8 wt.%Ag-0.7 wt.%Cu solder joints sandwiched between two Cu substrates with electroless nickel immersion gold (ENIG) metallization have been studied, and compared with the fracture behavior of joints attached to bare Cu. Irrespective of the surface finish, the fracture toughness of the solder joints decreased monotonically with strain rate and mode-mixity, both resulting in increased fracture proportion through the interfacial IMC layer. Furthermore, the proportion of crack propagation through the interfacial IMC layer increased with increase in the thickness and the roughness of the interfacial IMC layer and the yield strength of the solder, resulting in a decrease in the fracture toughness of the joint. However, under most conditions, solder joints with ENIG finish showed higher resistance to fracture than joints attached directly to Cu substrates without ENIG metallization. Based on the experimental observations, a fracture mechanism map is constructed correlating the yield strength of the solder, the morphology and thickness of the interfacial IMC, and the fracture mechanisms as well as the fracture toughness values for different solder joints under mode I loading.