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While halide and oxide perovskites are numerous and many display outstanding properties, ABN 3 perovskite nitrides are extremely rare due synthetic challenges arising from the low chemical potential of nitrogen and a tendency to form low-coordination nitridometallate anions. Here we report the preparation of a perovskite nitride LaReN 3 through azide-mediated oxidation at high pressure. High-resolution synchrotron diffraction shows that LaReN 3 has a low symmetry, triclinic, perovskite superstructure resulting from orbital ordering with strong spin-orbit coupling distortions. Topotactic reduction of LaReN 3 above 500 °C leads to layered tetragonal LaReN 2 via a probable LaReN 2.5 intermediate, the first reported examples of nitride defect-perovskites. Magnetisation and conductivity measurements indicate that LaReN 3 and LaReN 2 are both metallic solids. The two chemical approaches presented here are expected to lead to new classes of ABN 3 and defect ABN 3−x nitride perovskite materials.

International audience; Understanding the response of the surface of metallic solids to external electric field sources is crucial to characterize electrode–electrolyte interfaces. Continuum electrostatics offer a simple description of the induced charge density at the electrode surface. However, such a simple description does not take into account features related to the atomic structure of the solid and to the molecular nature of the solvent and of the dissolved ions. In order to illustrate such effects and assess the ability of continuum electrostatics to describe the induced charge distribution, we investigate the behavior of a gold electrode interacting with sodium or chloride ions fixed at various positions, in a vacuum or in water, using all-atom constant-potential classical molecular dynamics simulations. Our analysis highlights important similarities between the two approaches, especially under vacuum conditions and when the ion is sufficiently far from the surface, as well as some limitations of the continuum description, namely, neglecting the charges induced by the adsorbed solvent molecules and the screening effect of the solvent when the ion is close to the surface. While the detailed features of the charge distribution are system-specific, we expect some of our generic conclusions on the induced charge density to hold for other ions, solvents, and electrode surfaces. Beyond this particular case, the present study also illustrates the relevance of such molecular simulations to serve as a reference for the design of improved implicit solvent models of electrode–electrolyte interfaces.

The photoelectric effect consists of electrons emerging from the region near the inner surface of a metallic solid toward the outside vacuum, when the metal surface is illuminated. The effect depends on the frequency of the light waves and the properties of the metal surface. In particular, a minimum or “threshold” frequency of light is necessary to produce the effect in each metal.

Heteroepitaxial In2O3 films were grown on transparent c-sapphire substrates with 0, 3.5, 6, and 8° off-axis angles via low-pressure chemical vapor deposition (LPCVD). Metallic solid indium and oxyg...

The objective of this paper is to describe a new data-driven framework for computational screening and discovery of a class of materials termed “metavalent” solids. “Metavalent” solids possess characteristics that are nominally associated with metallic and covalent bonding (in terms of conductivity and coordination numbers) but are distinctly different from both because they show anomalously large response properties and a unique bond-breaking mechanism that is not observed in either covalent or metallic solids. The paper introduces the use of Hirshfeld surface analysis to provide quantum level descriptors that can be used for rapid screening of crystallographic data to identify potentially new “metavalent” solids with novel and emergent properties.

The present work proposes a new approach to the development of nanostructured ferromagnetic composites based on the progressive oxidation of high entropy alloys. Sequential ‘subtraction’ of the metals with lowest oxidation energy destabilizes the remaining solid solution, inducing phase separation at the nanoscale. By exploring immiscibility routes in the multidimensional phase diagram, the strategy can be used to promote intimate contact between mixed oxides and metallic solid solutions with desired magnetic properties. To demonstrate the concept, the relation between oxidation energy, phase separation and magnetic behavior has been investigated across the (CoCrCuFeNi)O x composition space, for 0.1 [[EQUATION]] x [[EQUATION]] 1.3, in materials produced by reactive sputtering. The results point out directions for tuning the composition when aiming for phases with specific magnetic properties arranged in complex microstructures.

Advanced materials 33(39), 2102356 (2021). doi:10.1002/adma.202102356, Published by Wiley-VCH, Weinheim

Physica status solidi / Rapid research letters 2000482 (2020). doi:10.1002/pssr.202000482, Published by Wiley-VCH, Weinheim

Recrystallization has been identified as a process in metallic solids since the “old days” (last part of the nineteenth century), when it was supposed that cold working of a metallic workpiece destroyed its crystallinity and that subsequent heating restored the crystalline nature by a process then naturally coined with the name “recrystallization”. Nowadays we would define recrystallization as a process that leads to a change of the crystal orientation (distribution) for the whole polycrystalline specimen, in association with a release of the stored strain energy as could have been induced by preceding cold work: a new microstructure results (Fig. 10.1). Recrystallization restores the properties as they were before the cold deformation. Recrystallization (and recovery and grain growth) occurs in all types of crystalline materials, so not only in metals. However, metals are the only important class of materials capable of experiencing pronounced plastic deformation at relatively low temperatures (i.e. low with respect to the melting temperatures), which explains that most of the corresponding research has been and is performed on metallic materials.

A quantitative understanding of the microscopic constraints, which underlie a well relaxed glassy structure, is the key to developing a microscopic theory of structural evolution and plasticity for the amorphous metallic solid. Here we demonstrate the applicability of one such theory of local bonding constraints developed by D. R. Nelson [Phys. Rev. B 28, 5515 (1983)] for a model binary Lennard-Jones glass structure. By introducing a modified radical Voronoi tessellation, which removes some ambiguity in how nearest-neighbor bonds are enumerated, it is found, that a large proportion $(g95%)$ of local atomic environments follow the connectivity rules of the SU(2) topology resulting in a dense network of disclination lines characterizing the defect bonds. Furthermore, it is numerically shown that a low-energy glass structure corresponds to a reduced level of bond-length frustration and thus a minimally defected bond-defect network. It is then demonstrated that such a defect network provides a framework to analyze thermally activated structural excitations, revealing those high-energy/low-density/elastically soft regions not following the connectivity constraints are more likely to undergo structural rearrangement that often ends with the creation of new SU(2) local topology content. The work provides a new analysis tool to study the connectivity of developing structural motives characteristic of isotropic undercooled liquids, their transition to a glass, and subsequent glassy structural relaxation.

The methodology used to measure transient temperature changes in impacted solids, using high-speed infrared detectors, is presented and discussed thoroughly. The various steps leading to a reliable measurement, namely selection of the sensing device, calibration of the setup, interfacing with the impact apparatus (Kolsky bar), and data reduction are presented. The outcome of the above methodology is illustrated in terms of the Taylor-Quinney factor, a well-known measure of the efficiency of the thermomechanical conversion.•Selection of infrared detectors.•Importance of the calibration procedure.•Determination of the Taylor-Quinney factor., Graphical abstract Image, graphical abstract

Superplasticity, which enables processing on hard-to-work solids, has been recognized only in metallic solids. While metallic materials and plastics (polymer solids) essentially possess high plastic workability, functional crystalline solids present difficulties in molding. Organic crystals especially are fragile, in the common view, and they are far from the stage of materials development. From the viewpoint of practical application; however, organic crystals are especially attractive because they are composed of ubiquitous elements and often exhibit higher performance than metallic materials. Thus, finding superplastic deformation of organic crystals, especially in a single-crystal-to-single-crystal manner, will pave the way for their material applications. This study confirmed superplasticity in a crystal of a simple organic compound: N,N-dimethyl-4-nitroaniline. The crystal exhibits single-crystal-to-single-crystal superplastic deformation without heating. This finding of “organosuperplasticity” will contribute to the future design of functional solids that do not lose their crystalline quality in molding., Superplasticity enables processing on hard-to-work solids but superelastic deformation, especially in a single-crystal-to-single-crystal manner, was not demonstrated for organic crystals so far. Here the authors demonstrate a single-crystal-to-single-crystal superplasticity in a crystal of N,N-dimethyl-4-nitroaniline.

The present work proposes a new approach to the development of nanostructured ferromagnetic composites based on progressive oxidation of high entropy alloys. Sequential ‘subtraction’ of the metals with the lowest oxidation energy destabilizes the remaining solid solution and induces phase separation at the nanoscale. By exploring immiscibility routes in the multidimensional phase diagrams, the strategy can be used to promote intimate contact between mixed oxides and metallic solid solutions with desired magnetic properties. To demonstrate the concept, the relation between oxidation energy, phase separation, and magnetic behavior has been investigated across the (CoCrCuFeNi)Ox composition space, for 0.1 ≤ x ≤ 1.3, in materials produced by reactive sputtering. The results point out directions for tuning the composition when aiming for phases with specific magnetic properties arranged in complex microstructures.

The two-dimensionally connected metal-organic frameworks (MOFs) Ni3(HIB)2 and Cu3(HIB)2 (HIB = hexaiminobenzene) are bulk electrical conductors and exhibit ultraviolet-photoelectron spectroscopy (UPS) signatures expected of metallic solids. Electronic band structure calculations confirm that in both materials the Fermi energy lies in a partially filled delocalized band. Together with additional structural characterization and microscopy data, these results represent the first report of metallic behavior and permanent porosity coexisting within a metal-organic framework.

Utilizing all-electron Dirac-exact relativistic calculations with the Normalized Elimination of the Small Component (NESC) method and the local vibrational mode approach, the transition from metal-halide to metal halogen bonding is determined for Au-complexes interacting with halogen-donors. The local stretching force constants of the metal-halogen interactions reveal a smooth transition from weak non-covalent halogen bonding to non-classical 3-center-4-electron bonding and finally covalent metal-halide bonding. The strongest halogen bonds are found for dialkylaurates interacting with Cl 2 or FCl. Differing trends in the intrinsic halogen-metal bond strength, the binding energy, and the electrostatic potential are explained.

Transient Liquid Phase (TLP) bonding was performed between Mg-AZ31 and Ti-6Al-4V alloys with various bonding temperatures using Cu coatings and Sn interlayers. The bonding parameters such as bonding pressure and bonding time were fixed at 1 MPa and 15 minutes respectively in order to study the effect of bonding temperature on the joint evolution. Bonds made at temperatures of 540, 560, 580 and 600 C showed good bond strength. The obtained bonds were investigated by Electron Probe Micro-analyzer EPMA and showed reaction layers and diffusion zones for all bonds made. The maximum joint shear strength of 78 MPa was obtained for bond made at 580 C. X-ray diffraction XRD and X-ray photoelectron spectroscopy XPS were taken for the fractured surfaces of bond made at 580 C. The analysis of the fractured surfaces found that the reaction layer contains Sn5Ti6 IMC in the titanium side and Mg2Cu IMC in the magnesium side where the fracture occurs at the diffusion zone in the mg side.

Modulus of resilience ( R ) in metallic solids is calculated based on Helmholtz energy analysis, free electron gas and acoustic phonon approximations: R = C + 2200 −1 (T - T D ) + 2200 −2 (T –T c ) 2 , where T, T D , T c is respectively the test, Debye, and Curie temperature, C is a material-specific constant. The model reproduces well experimental data in commercial titanium-, copper-, and four steels solids, and evaluates HfB 2 where experimental data are missing. It further suggests that only ∼0.1% of all the thermal free electrons/acoustic phonons are mechanically activated during the tensile test, which provides important insights on strain-electron-phonon coupling in solids.

Molecular dynamics simulations are performed to study the plastic deformation of Cu single crystals containing an elliptic cylindrical void. The effects of initial void geometry including void ellipticity and void orientation angle on plastic deformation are examined by considering the stress–strain response, dislocation nucleation from the void surface, and porosity/void cross-sectional shape evolution. It is found that (i) the initial void geometry plays an important role and (ii) the growth of voids with an increasing initial ellipticity converges to that of a crack. Our results reveal the underlying mechanisms of initial void ellipticity- and orientation angle-dependent plastic deformation of metallic solids, and provide direct evidence that there is no dividing line between a void and a crack in terms of the mechanical responses of these solids.

Although a resistivity saturation (minimum conductivity) is often observed in disordered metallic solids, such phenomena in the corresponding liquids are not known. Here we report a saturation of the electrical resistivity in ${\mathrm{Zr}}_{64}{\mathrm{Ni}}_{36}$ and ${\mathrm{Cu}}_{50}{\mathrm{Zr}}_{50}$ liquids above a dynamical crossover temperature for the viscosity (${T}_{A}$). The measurements were made for the levitated liquids under the microgravity conditions of the International Space Station. Based on recent molecular dynamics simulations, the saturation is likely due to the ineffectiveness of electron-phonon scattering above ${T}_{A}$ when the phonon lifetime becomes too short compared to the electron relaxation time. This is different from the conventional resistivity saturation mechanisms in solids.

The effect of temperature on the nonlinearity of ultrasonic waves propagating in metallic solids was studied experimentally. The metal block and rail were used as experimental objects respectively. The nonlinear parameters of ultrasonic bulk waves propagating in a metal block and ultrasonic guided waves propagating in a rail were measured during the temperature change process. The experimental results indicate that temperature has obvious influence on the nonlinearity of ultrasonic bulk waves or guided waves propagating in metallic solids. The ultrasonic nonlinear parameter of metallic solids increases with the increase of temperature and decreases with the decrease of temperature, which suggesting that it is necessary to compensate the effect of temperature when using nonlinear ultrasonic technology to detect relevant structures.

The use of an acoustic nonlinear response has been accepted as a promising alternative for the assessment of micro-structural damage in metallic solids. However, the full mechanism of the acoustic nonlinear response caused by the material micro-damages is quite complex and not yet well understood. In this paper, the effect of material microstructural evolution on acoustic nonlinear response of ultrasonic waves is investigated in rolled copper and brass. Microstructural evolution in the specimens is artificially controlled by cold rolling and annealing treatments. The correlations of acoustic nonlinear responses of ultrasonic waves in the specimens corresponding to the microstructural changes are obtained experimentally. To eliminate the influence of attenuation, which was induced by microstructural changes in specimens, experimentally-measured nonlinear parameters are corrected by an attenuation correction term. An obvious decrease of nonlinearity with the increase of grain size is found in the study. In addition, the influences of material micro-damages introduced by cold rolling on the acoustic nonlinear response in specimens are compared with the ones of grain boundaries controlled by heat treatment in specimens. The experimental results show that the degradation of material mechanical properties is not always accompanied by the increase of acoustic nonlinearity generated. It suggested that the nonlinear ultrasonic technique can be used to effectively characterize the material degradations, under the condition that the variations of grain sizes in the specimens under different damage states are negligible.

Low-fusing bonding agents have been widely applied in Ti-ceramics restorations. As an important category, borate bonding agents have great potentials in increasing Ti-porcelain bonding. The purpose of this study is to evaluate the effect of borate bonding agent with addition of Na2O and Al2O3 on Ti6Al4V-porcelain bonding. The thermal properties of borate bonding agent, such as glass transition temperature (Tg) and crystallization peak temperature (Tp), were investigated to establish the sintering process. And the coefficient of thermal expansion (CTE) was to evaluate the matching effect of porcelain to Ti6Al4V. The bond strength was analyzed by the three point bending test. The microscopic morphology of the borate bonding agent surface after sintering, the interface of Ti-borate bonding agent-porcelain, and the fracture mode after porcelains fracture, were studied to assess the influence of borate bonding agent on Ti6Al4V-ceramics. With the addition of Na2O and Al2O3, the porcelain residues were observed increased indication on the Ti6Al4V surface after porcelain fracture and the bond strength was acquired the maximum (49.45MPa) in the bonding agent composition of 75.70B2O3-5.92La2O3-11.84SrO-4.67Na2O-1.87Al2O3. Those results suggest that borate bonding agent is an effective way to improve the Ti6Al4V-ceramics bond strength. And the addition of Na2O and Al2O3 strengthen this effect.

In this study, the mechanism controlling the formation of a chemical bonding between a ceramic melt and a solid body prior to the melt solidification was investigated using the thermal spraying process as an example. The formation of a chemical bonding between TiO2, LCO, LZO, YSZ splats and ceramic substrates of the same material was investigated focusing on the effect of the deposition temperature. The bonding state was examined by studying both fractured cross-section samples and samples prepared utilizing the focused ion beam (FIB) technique. The microstructure at the interface of typical FIB-prepared cross section samples was examined by high-resolution transmission electron microscopy. The results show that an effective bonding at the splat interface can be formed only when the deposition temperature is higher than a critical bonding temperature. The critical bonding temperature linearly increases with the melting point of the ceramic material. The interface temperature, directly influencing the bonding formation, was calculated utilizing a one-dimensional heat transfer model. The maximum interface temperature corresponding to the critical bonding temperature was found to be close to the glass transition temperature of the splat material. Thus, the concept of an intrinsic bonding temperature and a sufficient condition for the formation of an efficient bonding are proposed. Furthermore, a model for the bonding mechanism at the melt/solid interface is established to explain the bonding formation and the microstructure at the interface.

The influence of correlation effects due to thermodynamic interaction of alloy components on segregation processes upon radiation treatment has been analyzed. The analysis has been performed for 53 metallic solid solutions. It has been shown that the short-range order in alloys causes a redistribution of flows of radiation defects and changes the mechanism of their annihilation, which in a certain temperature range is responsible for the high resistance of alloys to radiation swelling. The presence of two maxima in the curve of the temperature dependence of swelling for austenitic nickel–chromium alloys is associated with the existence therein of different types of short-range order at different temperatures.

Transient liquid phase (TLP) bonding process was applied to join magnesium alloy AZ31 samples with minimum microstructural changes. The magnesium samples were coated by 5 μm nickel prior to the TLP bonding. Bonding conditions of 8 MPa uniaxial pressure and 520 °C bonding temperature were applied for all bonds at various bonding times. The microstructure across the joint regions was examined as a function of bonding time (5–60 min). Investigating the change in Ni contents was examined by EDS line scan. It was noticed that Ni coating could not be observed by SEM for bonds made at 30 and 60 min due to complete dissolution of the Ni coating. Second phase particles containing Mg 2 Ni intermetallics were observed by X-ray Photoelectron Spectroscopy (XPS) near the joint region. The shear strength of the bonds initially increases with the increase in bonding time till 20 min. On the other hand, with bonding times over 20 min the shear strength decreases. Therefore the optimum bonding time at the conditions applied was concluded to be 20 min.

In this study, the effect of the metal salt generation bonding technique on the strength of a direct-bonded SUS304 stainless steel interface was investigated. SUS304 stainless steel surfaces were modified by boiling in 50% formic acid, and direct bonding was performed at a bonding temperature of 1023-1123 K under a pressure of 147 N (for a bonding time of 900 s). After direct bonding, the specimens were subjected to the peel test for evaluating their strength. As a result of the surface modification, bonded joints were obtained at bonding temperature of 30 K lower than that required for the unmodified surfaces, and the peel strength was comparable to that of the maximum load. On the basis of the experimental results, it was established that metal salt generation processing is effective for removing oxide films on SUS304 stainless steel.

Metallic composition of diesel particulate matter, even though a relatively small proportion of total mass, can reveal important information regarding engine conditions, fuel/lubricating oil characteristics and for health impacts. In this study, a detailed investigation into the metallic elemental composition at different particle diameter sizes has been undertaken. A bivariate statistical analysis was performed in order to investigate the correlation between the metallic element, measured engine performance and engine emission variables. Major sources of metallic elements in the emitted particles are considered in this study, including the fuel and lubricating oil compositions, engine wear emissions and metal-containing dust in the ambient air. Metallic solid ultrafine-particles (Dp 100 nm). Calculated correlation matrices show a clear effect of engine load conditions and fuel S contents on particle number and mass emissions.

Recent advances in high-pressure technologies and large-scale experimental and computational facilities have enabled scientists, at an unprecedented rate, to discover and predict novel states and materials under the extreme pressure-temperature conditions found in deep, giant-planet interiors. Based on a well-documented body of work in this field of high-pressure research, we elucidate the fundamental principles that govern the chemistry of dense solids under extreme conditions. These include: (i) the pressure-induced evolution of chemical bonding and structure of molecular solids to extended covalent solids, ionic solids and, ultimately, metallic solids, as pressure increases to the terapascal regime; (ii) novel properties and complex transition mechanisms, arising from the subtle balance between electron hybridization (bonding) and electrostatic interaction (packing) in densely packed solids; and (iii) new dense framework solids with high energy densities, and with tunable properties and stabilities under ambient conditions. Examples are taken primarily from low-Z molecular systems that have scientific implications for giant-planet models, condensed materials physics, and solid-state core-electron chemistry.

Shear is a basic deformation mode governing yielding, plasticity and fracture in metallic solids. For amorphous metals, due to various constraints, little work is available in addressing directly shear deformation and shear-induced mechanical property changes which are vital to the mechanistic understanding of this new class of disordered materials. Here, by using a finite deformation theory, we examine the pure shear deformation in a bulk metallic glass in a large range of shear strains. With the continuum approach, we show systematically for the first time the detailed shear deformation behaviours, shear-induced normal stress and strain relations, softening in the elastic constants, volume dilatation and free energy change induced by the shear deformation. These results point to two major consequences from the shear deformation, one is the mechanical degradations and the other material degradation which is responsible for the changes in the mechanical properties of the disordered materials.

High Entropy Alloys (HEAs) are new classes of structural metallic materials that show remarkable property combinations. Yet, often times interesting compositions are still found by trial and error. Here we show an “Effective Atomic Radii for Strength” (EARS) methodology, together with different semi-empirical and first-principle models, can be used to predict the extent of solid solution strengthening to discover and design new HEAs with unprecedented properties. We have designed a Cr45Ni27.5Co27.5 alloy with a yield strength over 50% greater with equivalent ductility than the strongest HEA (Cr33.3Ni33.3Co33.3) from the CrMnFeNiCo family reported to date. We show that values determined by the EARS methodology are more physically representative of multicomponent concentrated solid solutions. Our methodology permits high throughput, property-driven discovery and design of HEAs, enabling the development of future high-performance advanced materials for extreme environments.

Using a dynamic surface force apparatus, we investigate the nano-mechanics and the nano-rheology of an ionic liquid at dielectric and metallic solid surfaces. On smooth dielectric Pyrex surfaces, we find an ordered interfacial phase extending over less than 3 nm away from the top of the layer, with a compression modulus of 15 MPa extracted from the profile of the oscillatory forces. We discuss the boundary flow of the Newtonian bulk phase on this ordered interfacial layer. On metallic platinum surfaces, our hydrodynamic measurements evidence an interfacial soft solid layer extending up to 20 nm away from the top of the layer. The elastic modulus of this interfacial layer, derived from elasto-hydrodynamic measurements, is similar to the one found on Pyrex surfaces. Both on the dielectric and on the metal surfaces, the thickness of the interfacial phases is not found to change upon approach of the opposite surface, and does not exhibit a capillary-freezing transition.

International audience; The wettability of ceramic and metallic solids by liquid metals is discussed with emphasis on the effect of interfacial reactions on the spreading kinetics and the final degree of wetting. Two types of reaction are considered, simple dissolution of the solid in the liquid and dissolution followed by formation of a new compound at the interface. The review includes results obtained during the last 15 years mainly by the Grenoble group.

Boundaries and junctions (both internal and external) can contribute significantly to the plastic deformation of metallic solids, especially when the average size of the grains (phases) is less than hundred nanometres or when the size of the solid itself is of the order of microns. The overall permanent deformation of the solid is a result of a coupling between bulk plasticity with moving interfaces/junctions/edges and intrinsic plasticity of internal and external surfaces. We use a novel continuum thermodynamic theory of plastic evolution, with incoherent interfaces and non-splitting junctions, to derive flow rules for bulk and surface plasticity in addition to kinetic relations for interface, edge, and junction motion, all coupled to each other. We assume rate-independent associative isotropic plastic response with bulk flow stress dependent on accumulated plastic strain and an appropriate measure of inhomogeneity. The resulting theory has two internal length scales: one given by the average grain size and another associated with the material inhomogeneity.

In this study, powders of polyethylene oxide (PEO) and lithium perchlorate (LiClO 4 ) were used as the raw materials for producing the ionic conduction polymer PEO–LiClO 4 with different complex-ratios and used for anodic bonding through high energy ball milling method, and meanwhile, X-ray diffraction, differential scanning calorimetry (DSC), ultraviolet absorption spectrum test analysis, and other relevant methods were adopted to research the complexation mechanism of PEO and LiClO 4 and the impact of the ionic conduction polymer with different complex-ratios on the anodic bonding process under the action of the strong static electric field. The research results showed that the crystallization of PEO could be effectively obstructed with increased addition of LiClO 4 , thus increasing the content of PEO–LiClO 4 in amorphous area and continuously improving the complexation degree and the room-temperature conductivity thereof, and that the higher room-temperature conductivity enabled PEO–LiClO 4 to better bond with metallic aluminum and have better bonding quality. As the new encapsulating material, such research results will promote the application of new polymer functional materials in micro-electro-mechanical system (MEMS) components.

Conventional solids are prepared from building blocks that are conceptually no larger than a hundred atoms. While van der Waals and dipole-dipole interactions also influence the formation of these materials, stronger interactions, referred to as chemical bonds, play a more decisive role in determining the structures of most solids. Chemical bonds that hold such materials together are said to be ionic, covalent, metallic, dative, or otherwise a combination of these. Solids that utilize semiconductor nanocrystal quantum dots as building units have been demonstrated to exist; however, the interparticle forces in such materials are decidedly not chemical. Here we demonstrate the formation of charge transfer states in a binary quantum dot mixture. Charge is observed to reside in quantum confined states of one of the participating quantum dots. These interactions lead to materials that may be regarded as the nanoscale analog of an ionic solid. The process by which these materials form has interesting parallels to chemical reactions in conventional chemistry.

Cu/adhesive hybrid bonding is a promising technology to fabricate 3D integrated microsystems with ultra-fine pitch and short vertical interconnects, low electrical resistance, and high reliability. The main remaining issues of this technology include bonding temperature mismatch between Cu-Cu (350–400 °C) and adhesive (typically ≤250 °C), long thermal-compression time (low throughput), and high thermal stress. In this paper, we present a sub-200 °C Cu/adhesive hybrid bonding method. By using H-containing HCOOH vapor pre-bonding treatment, the bonding temperature is lowered to 180–200 °C and the thermal-compression time is shortened to 600 s, enabling a Cu-first hybrid bonding approach. Cu/adhesive hybrid bonding was successfully demonstrated at bonding temperature of 180 °C. The effects of prebonding treatment temperature and time on Cu-Cu bonding and cyclo-olefin polymer (COP) adhesive bonding are investigated in detail.

In this work we propose a non-perturbative approximation to the electronic stopping power based on the central screened potential of a projectile moving in a free electron gas, by Nagy and Apagyi. We used this model to evaluate the energy loss of protons and antiprotons in ten solid targets: Cr, C, Ni, Be, Ti, Si, Al, Ge, Pb, Li and Rb. They were chosen as canonicals because they have reliable values of the Seitz radio, rS=1.48-5.31 a.u., which cover most of the possible metallic solids. Present low velocity results agree well with the experimental data for both proton and antiproton impact. Our formalism describes the binary collision of the projectile and one electron of the free electron gas. It does not include the collective or plasmon excitations, which are important in the intermediate to high velocity regime. The distinguishing feature of this contribution is that by using the present model for low to intermediate energies (below the appearance of plasmon excitations), the Lindhard dielectric formalism (including plasmons) for intermediate to high energies, and the shellwise local plasma approximation to account for the inner shell contribution, then a good full-theoretical description of the available experimental data is obtained in an extensive energy range, covering the low, intermediate and high energy region., 13 pages including 8 figures

The reduction of post annealing temperature for plasma activated dielectric bonding was achieved by using SiCN as dielectrics layer. The SiCN-SiCN bonding shows higher bond energy at 250 °C as compared to conventional SiOi-SiOi bonding. The surface and interface of the SiCN bonding dielectric layers were characterized by various quantitative and qualitative methodologies. This alternative bonding dielectric allows development of extremely thin 3D integration devices with minimal thermal budget at bonding step.

In this study, a low temperature solid state diffusion bonding process with (111) highly oriented nano-twined Cu (nt-Cu) was proposed. A less void bonding interface was observed reveals a good bonding quality for the bonded samples. In addition, a large quasi-single grain was identified in the bondedfilm. Based on these results, it is believed that high strength and durable bonding structure can be accomplished by bonding two highly (111)-oriented nt-Cu films.

This study investigates the use of room temperature bonding for layer transfer process to reduce contaminants on a transferred material. It was found that resist residues on transferred graphene were significantly reduced using surface activated bonding at room temperature in comparison of thermal compression bonding at 250 °C. Surface activated bonding can provide a platform for layer transfer process suitable for 2D materials integration.

Solids are categorized as ionic, molecular, polycrystalline, covalent, metallic, and amorphous. Crystalline solids exhibit long-range order in the form of a lattice structure characterized by the three edges of a unit cell (a, b, and c) and the three angles relative to the axes of a Cartesian coordinate system (α, β, and γ). These parameters identify the 14 Bravais lattices associated with the crystal systems: cubic, tetragonal, orthorhombic, rhombohedral, hexagonal, monoclinic, and triclinic. In addition, the orientation of the lattice planes is identified by the Miller indices (hkl). Discussed in some detail with examples are metallic crystals (bismuth and iron pyrite), molecular crystals (sugar), covalent crystals (quartz, diamonds, and graphite), and amorphous solids (Silly Putty). The Law of Dulong and Petit for the heat capacities of solids is independent of temperature. This prediction is not what is observed in experiment as the temperature approaches absolute zero. The heat capacity also approaches zero in this temperature limit. Einstein showed in 1906 that if the vibration energy of the atoms in a solid were quantized at a single frequency, the heat capacity would exponentially decrease in the limit T → 0. In 1912 Debye extended the Einstein model to include a broad range of frequencies for phonon modes in a crystal. Adsorption of particles on a lattice is examined with simple one-dimensional lattice models. At one extreme only one adsorption layer is allowed. This is the well-known Langmuir model that is used in the interpretation of titration data. The other extreme is unlimited adsorption at any one site. This is the Brunauer–Emmett–Teller theory, known by the abbreviation B.E.T.

We report a low-temperature thermo-compression bonding process that utilizes chemical surface activation and is useful in 3D integration processing of wafers. Cu possesses desirable properties, such as ideal electrical properties, good thermal conductivity, and longer electro-migration times, making it an attractive interlayer material for the 3D integration process. However, in general, a high thermal energy of 400 °C or more is required for Cu-Cu bonding to be successful. In order to address this problem, this investigation sought to confirm chemical activation of a Cu surface during the bonding process by using atomic force microscopy (AFM) to measure the bonding strength. The reliability of AFM has been established in previous research. The bonding strength of the Cu was determined to be about 6.7 J/m2 at 150 °C. This bonding strength can be used for 3D integration applications, and the possibility of low-temperature thermo-compression was confirmed by chemical surface activation.

High entropy alloys (HEAs), or concentrated solid solution alloys, are chemically complex metallic solid solutions in which five or more elements occupy the same crystallographic lattice sites with nearly equal compositions. The high degree of chemical disorder gives rise to considerable local lattice distortions, atomic-level stresses, and complex electronic structure, resulting in interesting properties. We calculated the electronic structure and the atomic-level stresses of AlxTiyZryPdyCuyNiy, x = 0.5, y = 1 (Al0.5TiZrPdCuNi) HEA in the glassy phase using the density functional theory (DFT) approach. We also briefly discuss the electronic structure in its crystalline phase. Whereas it has been reported recently that the crystalline phase of this HEA is obtained as a metastable phase during the crystallization of a glassy phase, the crystalline phase was found to be unstable at T = 0 in the DFT calculation. For this reason, we focus mainly on the glassy phase in this work. The importance of charge transfer among elements on the atomic-level pressure and the role for atomic-level stresses to characterize the electronic and structural heterogeneity are discussed.

The study is diffusion bonding of Mg-AZ31 and Al-6061 under pressure and no pressure by using the direct bonding method. After bonding process, characteristics phase in interface and bonding boundaries of Mg-AZ31/Al-6061 were characterized . The diffusion formation was observed by SEM. Aluminum solid solution and Mg17Al12 alloy phase was proved by analysis of XRD. In the process of measurement, crystalline structure of nearby interface characteristics phase was analyzed in detail by TEM. Based on the above analysis, the crystal model of the magnesium alloy and aluminum alloys was established under pressure, and the bonding mechanism was discussed. The results show that the bonding materials could be bonded under no pressure and the structure of bonding interface is more optimized than pressure.

The electronic structure and elastic properties of the 4d transition metal carbides MC (M = Y, Zr, Nb, Rh) were studied by means of extended Huckel tight-binding band electronic structure calculations. As the valence electron population of M increases, the bulk modulus of the MC compounds in the rocksalt structure does not increase monotonically. The dominant covalent bonding in these compounds is found to be M-C bonding, which mainly arises from the interaction between M 4d and C 2p orbitals. The bonding characteristics between M and C atoms affecting the variation of the bulk modulus can be understood on the basis of their electronic structure. The increasing bulk modulus from YC to NbC is associated with stronger interactions between M 4d and C 2p orbitals and the successive filling of M 4d-C 2p bonding states. The decreased bulk modulus for RhC is related to the partial occupation of Rh-C antibonding states. clarified in these studies are useful in interpreting their physical properties. The common viewpoint is that covalent bonds can be formed between both metal-carbon and metal-metal pairs of atoms. At the same time, a transfer of electrons from M to C takes place, implying a certain degree of ionic bonding. We stress the importance of covalent metal-carbon bonds in explaining the stability and observed mechanical properties of these compounds. These pro- perties are understood to arise in large part from strong covalent bonding between transition metal d and carbon p orbitals. In this paper, we present the results of the electronic structures calculated for the carbides of 4d transition metals Y, Zr, Nb, and Rh. The presence of covalent M-C bonds and metallic M-M bonds is confirmed and analyzed in detail. In addition, the number of valence d electrons in the metals induces changes in bonding and elasticity in these compounds. It is, therefore, our goal to understand the relationship between the M-C bond strength and elastic properties of 4d transition metal carbides (MC) in the rocksalt structure as a function of the valence electron concentration (VEC) per atom, which is the total number of valence electrons in the structure divided by the number of atoms in a unit cell. As the VEC increases, the bulk modulus (B) increases from YC to NbC, and then decreases for RhC. This variation of B with the number of metal d electrons can be explained as arising from the orbital mixing between metal and carbon and the successive filling of the consequent bonding and antibonding M 4d-C 2p states. The focus is on the trends in the electronic structure and the nature of bonding, which are essential for the understanding of the elastic properties of the transition metal carbides. Our approach is based on a thorough complementary analysis of the density of states (DOS) and crystal orbital overlap population (COOP) to gain more profound insight into the bonding of this class of materials and get more detailed information on the bonding character than previous- ly achieved. The COOP curves are indicative of the nature and strength of the bonding between a given pair of atoms, with positive and negative regions indicating bonding and antibonding states, respectively. The chemical bonding of M-C and M-M is quantitatively discussed by use of the bond overlap population based on supercell band structure calcu- lations.

Electronic structure and chemical bonding in tetragonal KNbO3 have been studied by first-principles calculations. The band gap is indirect and a value of 1.64 eV was determined. Chemical bonding feature shows that a significant hybridization between Nb 4d and O 2p states. The bonding between K and NbO3 is mainly ionic nature while covalent nature was confirmed between Nb and O.

This paper studies mainly the diffusion bonding of 3Y-TZP/SUS304 by using the chemical bonding method. In the bonding interface of 3Y-TZP and SUS304, the Ti-Cu powder/sheet was used as bonding materials. In bonding process, multi-alloy with Fe-Ti and Fe-Cu have been confirmed by Electron Probe Micro-Analyzer (EPMA) determination. Through the microstructure observed by AFM and SEM, bonding boundaries of 3Y-TZP/SUS304 by Ti-Cu powder/sheet had good formation. The distribution of the residual stress on near interface was measured by XRD method. By using of these results, the mechanism of the ceramic and stainless steel was discussed.