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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.

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

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 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.

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 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.

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.

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.

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

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 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.

Aluminum alloys have high strength and are easily recyclable owing to their low melting point. Therefore, aluminum is widely used for manufacturing cars and electronic devices. Currently, the most common method for bonding aluminum surfaces is brazing. However, brazing requires positional accuracy and results in the formation of voids by the flux residue; therefore, to avoid these problems, solid-state bonding methods are considered as a possible alternative. However, solid-state bonding also suffers from some problems that need to be overcome. One of these problems is the presence of an oxide film on aluminum surfaces, necessitating the need to remove or destroy the oxide film without applying high temperature and high load. Hence, in this study, a bonding surface was treated with NaOH (aq) for removing the oxide film; moreover, the effectiveness of this treatment was determined by observing the bonding interfaces and fractured surfaces of specimens. For solidstate bonding, the specimens were first subjected to surface modification by boiling the specimens in NaOH (aq) for 20s. Solid-state bonding was then carried out at bonding temperatures ranging from 693 to 813K in a vacuum chamber with the bonding pressure and bonding time fixed at 6MPa and 1.8ks, respectively. After solid-state bonding, the specimens were subjected to the tensile test for evaluating their strength. The results revealed that the tensile strength of a joint increased with the bonding temperature with or without surface modification. Moreover, surface modification resulted in high-strength joints with less deformation at low bonding temperatures. In addition, the bonding temperature and degree of deformation needed to achieve joints with strength higher than the 0.2% proof stress of aluminum were 100K and 25% lesser, respectively, in the case of surface modification. On the basis of the experimental results, it was established that surface modification is effective for removing oxide films and processing layers on an aluminum surface. [doi:10.2320/matertrans.M2013101]

The application of pressure, internal or external, transforms molecular solids into non-molecular extended network solids with diverse crystal structures and electronic properties. These transformations can be understood in terms of pressure-induced electron delocalization; however, the governing mechanisms are complex because of strong lattice strains, phase metastability and path dependent phase behaviors. Here, we present the pressure-induced transformations of linear OCS (R3m, Phase I) to bent OCS (Cm, Phase II) at 9 GPa; an amorphous, one-dimensional (1D) polymer at 20 GPa (Phase III); and an extended 3D network above ~35 GPa (Phase IV) that metallizes at ~105 GPa. These results underscore the significance of long-range dipole interactions in dense OCS, leading to an extended molecular alloy that can be considered a chemical intermediate of its two end members, CO2 and CS2.

This paper explores a fundamental connection between ductility and domain size in metallic solids under extreme conditions of cryogenic temperatures and strain rates (10 8 s –1 ). A series of novel experiments, backed by multiscale modelling and transmission electron microscopy (TEM) analysis, are presented that involve loading of TEM-ready single crystal nanopillar samples of Cu of varying lengths (50 nm to 1 mm) and aspect ratios (50 nm to 100 nm in diameter) by laser-generated stress waves of sub-nanosecond rise times, under extreme conditions of strain rate (>10 8 s –1 ) and temperature (100K). The nucleation stress for Shockley partials, which can be taken as a proxy for the onset of ductile deformation, was measured to be only 1 GPa. This is an order of magnitude lower than the previously measured values of 35 GPain bulk geometries. TEM observations show remarkable ability of the material to re-arrange itself through motion of dislocations to form subgrain boundaries within a very short duration of only few nanoseconds.

Doping with the optimum concentration of carriers (electrons or holes) can modify the physical properties of materials. Therefore, improved ways to achieve carrier doping have been pursued extensively for more than 50 years. Metal-intercalation is one of the most important techniques for electron doping of organic / inorganic solids and has produced superconductors from insulators and metallic solids. The most successful examples are metal-intercalated graphite and C60 superconductors. Metal intercalation has been performed using solid-reaction and liquid solvent techniques. However, precise control of the quantity of intercalants in the target solids can be difficult to achieve using these methods, as that quantity depends largely on the initial conditions. Here we report an electrochemical method for metal-intercalation and demonstrate the preparation of superconductors using organic and inorganic materials (C60 and FeSe). The metal atoms are effectively intercalated into the spaces in C60 and FeSe solids by supplying an electric current between electrodes in a solvent that includes electrolytes. The recorded superconducting transition temperatures, Tc’s, were the same as those of metal-intercalated C60 and FeSe prepared using solid-reaction or liquid solvent techniques. This technique may open a new avenue in the search for organic / inorganic superconductors.

Transient liquid phase (TLP) bonding is a relatively new bonding process that joins materials using an interlayer. On heating, the interlayer melts and the interlayer element (or a constituent of an alloy interlayer) diffuses into the substrate materials, causing isothermal solidification. The result of this process is a bond that has a higher melting point than the bonding temperature. This bonding process has found many applications, most notably the joining and repair of Ni-based superalloy components. This article reviews important aspects of TLP bonding, such as kinetics of the process, experimental details (bonding time, interlayer thickness and format, and optimal bonding temperature), and advantages and disadvantages of the process. A wide range of materials that TLP bonding has been applied to is also presented. Partial transient liquid phase (PTLP) bonding is a variant of TLP bonding that is typically used to join ceramics. PTLP bonding requires an interlayer composed of multiple layers; the most common bond setup consists of a thick refractory core sandwiched by thin, lower-melting layers on each side. This article explains how the experimental details and bonding kinetics of PTLP bonding differ from TLP bonding. Also, a range of materials that have been joined by PTLP bonding is presented.

The available experimental data for metallic solid solutions in the rhenium-rhodium binary metallic system are incomplete. This paper reviews recent data on the Re-Rh system which enables the solidus parts of the equilibrium phase diagram to be constructed. Experimental data for solid solutions prepared by different techniques and theoretical modelling show that the single phase regions are wider than previously reported. The maximum solid phase solubility of Re in Rh is 15 at%, and that of Rh in Re is 75 at%. In this paper, a phase diagram for the Re-Rh system which serves as a reliable model for the representation of the available experimental data is proposed.

Initiated by Gustav E.R. Schulze, pioneering experimental and theoretical work on Laves phases was done in Dresden/East Germany after World War II, which was then part of the German Democratic Republic GDR behind the former Iron Curtain. Due to Cold War restrictions, many of the results have not become known to the West. The present overview gives an insight into the compounds dealt with, the properties measured, the features calculated and the conclusions drawn. Starting with concepts of crystal chemistry, like inflated coordination number or maximum density, rules for the formation of Laves phases have been established. One focus of the experimental work was the impact of deviation from stoichiometric composition upon structure and physical properties. Mutual substitution of A and B atoms in AB2 phases was identified as prevalent constitutional defect. Apart from structural studies employing X-ray and neutron diffraction, various physical properties of selected members have been measured, like electrical and thermal conductivity, heat capacity, magnetic susceptibility, thermal expansion, diffusion coefficient, and optical constants. Computations of electron and phonon spectra of selected Laves phases from first principles helped to correct the naive simple-metal-view upon those metallic solids and to understand physical properties more thoroughly. As another main field of research, studies of the plasticity and real structure of certain Laves phases are reviewed. Macroscopic stress–strain behaviour has been broken down to dislocation dynamics using Orowan’s equation. An important role of Peierls stress as obstacle to dislocation movement has been concluded from that. In addition, changes of dislocation density and geometry within the range of homogeneity were characterized quantitatively. Alloy softening was found with off-stoichiometric compounds due to an elevated density of grown-in dislocations.

A new kind of leaky wave antenna based on low-frequency surface plasmon polaritons (SPPs) is proposed, which is constructed by periodic metallic blocks with an open slot on the top. Numerical analysis shows that by introducing the open slot on the metallic blocks, there will appear extra spoof SPPs modes in the band gap of metallic solid blocks. The dispersion curve of such spoof SPPs modes passes through the light line and enters into the radiation region, and consequently it can generate a frequency steering pencil-like radiation. Experimental verification agrees with the theory.

Hydrodynamic simulations have been carried out using the multi-physics radiation hydrodynamics code HYDRA and the simplified one-dimensional hydrodynamics code DISH. We simulate possible targets for a near-term experiment at LBNL (the Neutralized Drift Compression Experiment, NDCX) and possible later experiments on a proposed facility (NDCX-II) for studies of warm dense matter and inertial fusion energy-related beam-target coupling. Simulations of various target materials (including solids and foams) are presented. Experimental configurations include single-pulse planar metallic solid and foam foils. Concepts for double-pulsed and ramped-energy pulses on cryogenic targets and foams have been simulated for exploring direct drive beam-target coupling, and concepts and simulations for collapsing cylindrical and spherical bubbles to enhance temperature and pressure for warm dense matter studies.

Spontaneous formation of binary-phase hollow nanospheres by reaction of a metallic nanosphere with a non-metallic component in the surrounding atmosphere is observed for many systems. The kinetic model describing this phenomenon is derived by application of the thermodynamic extremal principle. The necessary condition of formation of the binary-phase hollow nanospheres is that the diffusion coefficient of the metallic component in the binary phase is higher than that of the non-metallic component (Kirkendall effect occurs in the correct direction). The model predictions of the time to formation of the binary-phase hollow nanospheres agree with the experimental observations.

Borosilicate glass is often used as a material during the anodic bonding process because the thermal expansion coefficient of glass is very close to that of silicon. However, in recent years, a new chemical composition of glass was developed as a joinable glass at a lower bonding temperature. To ensure the reliability of anodic bonding joints of the new glass to silicon, it is necessary to clarify the influence of bonding conditions and the comparison of performance of anodic bonding joints of new glass and borosilicate glasses. In this study, the effect of the bonding conditions on the tensile strength and thickness of the reaction layer and bonding charge density of anodic bonding joint of three glasses (TEMPAX, PYREX, SW-YY) to silicon was comparatively investigated. The main results obtained are as follows. The anodic bonding joints using SW-YY was bonded at a lower bonding temperature than TEMPAX and PYREX. Under the same bonding conditions, thickness of the reaction layer on joints of SW-YY to silicon was the thickest of all. Independent of glasses, the increase in the bonding charge density resulted in stabilized tensile strength and the fracture modes changed to glass fractures. Thus, measuring the bonding charge density during the anodic bonding process helped to clarify the effects of the bonding conditions on the anodic bonding joints of glass to silicon.

Wetting of single-crystal surfaces of metallic solids and oxides by liquid metals and alloys is anisotropic because of the anisotropy of the energies of solid surfaces and of their interfaces with liquids. To provide a basis for a discussion of wetting anisotropy, we review first the literature on surface and interfacial energies in metal-metal and metal-ceramic systems. We then summarize the relevant literature on the anisotropy of the energies of solid surfaces and of solid-liquid interfaces. These energies are then used in conjunction with the Young equation to estimate the expected anisotropy of wetting. Some serious discrepancies are found between these estimates and the experimental anisotropy of wetting. We show that under certain experimental conditions the wetting angles that have been determined are not Young contact angles.

Since Anodic bonding of silicon to glass is solid state bonding, it is often used as a MEMS manufacturing technology when accuracy of dimensions is required. However, it is necessary to clarify the relation between bonding conditions or glass compositions and the mechanical properties of anodically bonded joints such as tensile strength and fracture mode. The influence of environmental factors such as high temperature and high humidity on the joints is also not well understood. This study was conducted to investigate the influence of bonding conditions on mechanical properties and on growth of the reaction layer at the bond interface. Moreover, since the transfer of electric charge in the bond interface is likely to be closely related to the anodic bonding reaction, the bonding charge density which flowed into the bond interface was measured during the bonding process, and the relation between the bonding charge density and the tensile strength or the reaction layer was examined. At bonding temperatures below 300°C, tensile strength increased with the bonding time and bonding voltage. At bonding temperatures above 350°C, increasing the bonding time and bonding voltage did not influence tensile strength. At bonding conditions of low charge density, the observed fracture mode was interface fracture. As the bonding charge was increased, tensile strength was stabilized and the fracture mode changed to glass fracture. As the bonding charge density was increased, the reaction layer became thicker, and growth of the reaction layer was controlled by the bonding charge density. There was a tendency towards greater tensile strength with thicker reaction layers. Thus, measuring boding charge during the bonding process helped to clarify the effect of bonding conditions on the joints.

The structural and electronic properties of TiB 2 have been calculated using the first-principles total-energy pseudopotential method based on density functional theory. It is shown that the calculated lattice constants and heat of formation of TiB 2 are in good agreement with the experimental results. By analyzing the band structure, density of states and Mulliken population, it is found that the bonding nature in TiB 2 is a combination of ionic, covalent and metallic. The 2s–2p interaction exists in the close-packed layer of boron atoms. The hybridization of Ti-3d and B-2p from different layers is the main reason for the creation of pseudogap and results in the strong interlayer covalent bonding. In the same time, the charge transfer from titanium to boron is as significant as 1.16 electrons in the present case. The d–d resonance and free-electron 3d states of titanium atoms contribute to the covalent and metallic bonding in the layer of titanium atoms.

We utilized a thermal radiation method to synthesize semiconducting hollow ZnO nanoballoons and metal-semiconductor concentric solid Zn/ZnO nanospheres from metallic solid Zn nanospheres. The chemical properties, crystalline structures, and photoluminescence mechanisms for the metallic solid Zn nanospheres, semiconducting hollow ZnO nanoballoons, and metal-semiconductor concentric solid Zn/ZnO nanospheres are presented. The PL emissions of the metallic Zn solid nanospheres are mainly dependent on the electron transitions between the Fermi level (E(F)) and the 3d band, while those of the semiconducting hollow ZnO nanoballoons are ascribed to the near band edge (NBE) and deep level electron transitions. The PL emissions of the metal-semiconductor concentric solid Zn/ZnO nanospheres are attributed to the electron transitions across the metal-semiconductor junction, from the E(F) to the valence and 3d bands, and from the interface states to the valence band. All three nanostructures are excellent room-temperature light emitters.

Diffusion bonding and explosive welding of oxide dispersion strengthened silver (ODS-Ag), which is one of electric contact materials, to copper (Cu) have been conducted to compare their interfacial microstructures and bonding strength. The diffusion bonding was carried out at 973 K for 3.6 ks to achieve solid state bonding. Defects like void were observed at the interface in the diffusion bonded ODS-Ag/Cu joint. It is considered that insufficient contact at the interface is responsible for the formation of the defect. The shear strength of this joint was less than 40 MPa and far inferior to that of Ag/Cu joint produced under the same condition. On the other hand, the explosively welded joint had no defects in the collision interface. Its bonding strength exceeded that of the diffusion bonded Ag/Cu joint, and was about four times as high as that of the ODS-Ag/Cu joint fabricated by diffusion bonding. From the results of TEM observations, microstructural aspects of the ODS-Ag in the vicinity of the collision interface appear to be similar to those observed before bonding. This suggests that the characteristics of the ODS-Ag as a electric contact material are retained even after the bonding treatment. Therefore, the solid state bonding with momentary high pressure such as explosive welding is suited to the bonding method for the ODS-Ag materials.

To make full use of the strength of carbon nanotubes in a composite, it is important to have a high-stress transfer at the matrix−nanotube interface via strong chemical bonding. This paper investigates the possible polyethylene−nanotube bonding with the aid of a quantum mechanics analysis. The polyethylene chains were represented by alkyl segments, and the nanotubes were modeled by nanotube segments with H atoms added to the dangling bonds of the perimeter carbons. The study predicts that covalent bonding between an alkyl radical and a nanotube is energetically favorable, and that the tubes of smaller diameters have higher binding energies. Hence, a high-stress transfer can be realized in polyethylene-based carbon nanotube composites in the presence of free-radical generators.

Liquid film protection (LFP) method combined with press bonding technique was employed to perform solid-state bonding experiments of AA7075 aluminum alloy in this study. The purpose of this study is to demonstrate the applicability of this new solid-state bonding process to common non-superplastic aluminum alloys. A liquid film protection (LFP) technique is used in this process to protect bonding surface from contacting the environment instead of the expensive vacuum and atmosphere protection equipments prior to press bonding. Effectiveness of this process is studied for various combinations of process parameters, the bonding temperature, the amount of press deformation, and the holding time. Metallographic observations reveal that the bonding interface looks like a wiggled line showing an evidence for a good solid-state bonding. The highest bonding strength and contact ratio reached in this study are 169.3 MPa (about 63% of the base metal) and 82.6%, respectively. Experimental results indicate that press deformation is by far the essential parameter in solid-state bonding process. The bonding strength and the contact ratio tend to increase with deformation. Experimental results also show that fine grains possessed by superplastic materials do increase the bonding strength and contact ratio, but the contribution is very small. The way to provide a clean surface without oxide film is the key factor for a successful solid-state bonding of aluminum alloys.

Solid-state bonding of superplastic 5083, 7475, and 8090 Al-alloys is studied herein. Press bonding was employed to study the ability of bonding aluminum alloys in air. The test sheets were sealed in a plastic bag filled with argon gas before bonding and directly bonded in air. The bonds produced demonstrated that the bond strength was influence strongly by the bonding parameters and the nature of the material. A large deformation was needed for superplastic Al-alloys to be bonded directly in air. The bondability of different alloys depended on the nature of the oxide layer on the surface and the stability of grain structure. Sealing the test sheets in a plastic bag filled with argon gas could enable a smaller deformation and a shorter holding time to be employed for Al-alloys to be bonded in air.

First principles electronic structure studies on the ground state geometries, stability, and the electronic structure of AlnNam and AlnMgm (m ≤ 3, n + m ≤ 15) clusters have been carried out to examine the nature of bonding between Na or Mg and Al. Identifying whether the bonding is ionic or metallic in bulk materials is typically straightforward; however, in small clusters where quantum confinement is important, the nature of bonding may become unclear. We have performed a critical analysis of the bonding in these bimetallic clusters using charge analysis, electrical dipole moments, hybridization of the atomic orbitals, the Laplacian of the charge density at the bond critical points, and the change in the bonding energy between neutral and anionic forms of the cluster. For NanAlm clusters, we find that the Na binding is primarily ionic, while the bonding in AlnMgm is primarily metallic. We find that the Mulliken population of the 3p orbital of Na and Mg can provide a rapid assessment of the nature of bonding. We also find that the Hirshfeld charge and dipole moments are effective indicators, when placed in context. We found that the Laplacian of the charge density at the bond critical points can be misleading in identifying whether the bonding is ionic or metallic in small clusters.

Copper nanoparticles (Cu NPs) fabricated by physical vapor deposition (PVD) were introduced in Cu-Cu bonding as surface modification. The bonding structure with Ti adhesive/barrier layer and Cu substrate layer was fabricated on both surfaces first. Loose structure with Cu NPs was then deposited by magnetron sputtering in a high pressure environment. Solid state Cu-Cu bonding process was accomplished at 200°C for 3min under the pressure of 20MPa. Die shear test was carried out and an average bonding strength of 36.75MPa was achieved. The analysis of fracture surface revealed a high-reliability bonding structure. According to cross-sectional observations, a void-free intermediate Cu layer with thickness around 10nm was obtained. These results demonstrated that a reliable low temperature time-saving Cu-Cu bonding was realized by Cu NPs between the bonding pairs. This novel bonding method might be one of the most attractive techniques in the application of ultra-fine pitch 3D integration.