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Molecular dynamics simulations are performed to investigate the effect of the interface structure, diffusion time and diffusion temperature on the diffusion behavior and amorphization mechanism of the dual-phase Mg alloys. The results indicate that there is a critical concentration of Y element in the amorphous/crystalline interface (ACI), which depends on the interface structure and temperature. And when the concentration of Y atoms in the ACI is higher than the critical concentration, the ACI will migrate towards the crystalline side, accompanied by the amorphization of the crystalline layer. In addition, it is found that the presence or absence of Y element in the amorphous layer has a significant impact on the amorphous layer thickness of the alloys. For the alloys containing Y atoms, the amorphous layer thickness increases with the increase of diffusion temperature and diffusion time. [ABSTRACT FROM AUTHOR]

A novel electrocatalyst containing amorphous FeSeO x and Mo doped NiSe 2 (denoted as FeSeO x /Mo-NiSe 2) was developed via pseudocrystalline replication method and selenization treatment, and heteroatom doping and amorphous and crystalline (a-c) interface enables attractive OER performances. [Display omitted] • A novel FeSeO x /Mo-NiSe 2 electrocatalyst was desinged for water oxidation. • The optimized FeSeO x /Mo-NiSe 2 exhibits a low overpotential of 205 mV at 10 mA cm−2 for OER in alkaline solution. • The excellent performance is attributed to amorphous and crystalline (a-c) interface engineering and heteroatom doping strategies. Exploring integrated regulation strategies to boosting electrocatalytic performance is essential to design more efficient and inexpensive OER catalysts. Herein, amorphous and crystalline (a-c) interface engineering and heteroatom doping are integrated to construct a novel electrocatalyst containing amorphous FeSeO x and crystalline Mo-doped NiSe 2 (denoted as FeSeO x /Mo-NiSe 2) via pseudocrystalline replication method and selenization treatment. The resultant FeSeO x /Mo-NiSe 2 electrocatalyst with 3D hierarchical nanoarchitectures of nanorod arrays covered by interlocking nanoblocks exposes more active sites and accelerated reaction kinetics. Furthermore, a-c interface engineering and heteroatom doping can synergistically enhance the intrinsic activity and charge transfer capability of NiSe 2 by decreasing the electron diffusion distance and flexibly modulating the electronic structure, which contributes to boost the oxygen evolution reaction (OER) performance. Consequently, the obtained FeSeO x /Mo-NiSe 2 achieves a low overpotential of 205 mV at 10 mA cm−2, which outperforms many other transitions metal selenides electrocatalysts. Density functional theory (DFT) calculations demonstrate that the formation of an internal electric field between FeSeO x and Mo-NiSe 2 accelerates charge transport and optimizes the adsorption/desorption of oxygen-containing intermediates, thereby accelerating the reaction kinetics and improving the OER performance. This work serves as a point of reference for designing innovative metal selenides based electrocatalysts combining a-c interface engineering and heteroatom doping. [ABSTRACT FROM AUTHOR]

Sodium ion batteries (SIBs) have garnered more and more attentions owing to the uneven distribution and increasing price of lithium mineral. Herein, BiVO 4 –V 2 C endogenous heterostructures as anode for SIBs are synthesized via one-step in situ hydrothermal method. The designed hydrangea-like heterostructure ensures a wide contact surface for the interaction of anode material with the electrolyte, and endows stable heterojunction interfaces between BiVO 4 and V 2 C MXene, the synergistic effect of which significantly improves the electrical conductivity, pseudo-capacitance and alleviates the volumetric change of BiVO 4 during charge/discharge process. Density functional theory (DFT) calculations ulteriorly demonstrate that the electric field at the BiVO 4 –V 2 C interface contributes to the excellent Na ion diffusion kinetics and impressive sodium storage capacity. As a result, the BiVO 4 –V 2 C anode achieved outstanding performance with a high discharge capacity (480 mAh g−1 after 600 cycles at 0.2 A g−1), and impressive long-term lifespan (303 mAh g−1 over 2000 cycles at 1 A g−1). This work reveals a new design of novel V 2 C MXene heterojunctions which coupling with BiVO 4 combined with the analysis of amorphous/crystalline interface, developing a proper strategy for the effective energy storage of sodium. An endogenous heterostructure of BiVO 4 coupled with V 2 C MXene (BiVO 4 –V 2 C) is developed via a one-step hydrothermal method. The designed hydrangea-like heterostructure provides a large surface area for the contact of the electrode material with electrolyte, and endows stable heterojunction interfaces between BiVO 4 and V 2 C, which significantly improves the reaction kinetics. [Display omitted] • Hydrangea-like endogenous BiVO 4 –V 2 C heterostructure is firstly reported. • Internal micro-electric field for improving Na+ migration and reaction kinetics. • The electrode delivers superior specific capacity and excellent cycle stability. • Endogenous heterostructure offers new insights for MXenes heterojunctions design. [ABSTRACT FROM AUTHOR]

Experiments have shown that high strength and high plastic stability are difficult to be simultaneously obtained in crystalline-amorphous layered composites. Here we report a complete suppression of plastic instability in a strong multilayered composite via nanoscale BCC Nb crystalline-amorphous CuNb interface architecting. Specifically, the size-dependent hardness and shear instability of the designed nanolayered composites are systematically investigated with individual layer thickness (h) ranging from 2 to 100 nm by nano/micro-indentation tests. A mechanics model is also proposed to quantify the shear instability. A non-monotonic shear instability behavior is revealed with decreasing h. When h > 40 nm, a cutting-like shear banding prevails in the composites and the shear instability reduces with decreasing h. Finally, a homogeneous plastic deformation without shear banding is achieved at h of 40 nm. For h < 40 nm, a kinking-like shear banding occurs in the composites and the shear instability increases with reducing h. Further theoretical analysis reveals a critical layer thickness for activating homogeneous deformation in the composites, i.e., 45 nm, above and below which the shear deformation would be dominated by cutting-like and kinking-like shear banding, respectively. The cutting-like shear banding is attributed to the propagation of the mature shear band formed in the amorphous phase that penetrates the crystalline layer. The homogeneous plastic deformation can be ascribed to the activation of the confined layer slip mechanism in the crystalline layer and the non-clustered shear transformation zones initiated in the amorphous layer. The kinking-like shear banding below 40 nm may originate from the cooperative kinking of the constituent layers with decreasing h. The potential advantage of the ductile BCC metals over FCC ones for suppression of shear instability in crystalline-amorphous composites is discussed based on the unique dislocation activities in nanoscale BCC crystals (e.g., self-multiplication and significant cross-slipping mechanisms). The present study sheds some light on designing strong and ductile crystalline-amorphous composites by selecting an appropriate BCC crystalline phase and an optimal interface spacing to eliminate plastic instability. • Shear instability of Nb/amorphous CuNb nanolayered composites is studied. • A mechanics model is proposed to quantify the shear instability. • A non-monotonic shear instability is discovered with decreasing layer thickness. • Shear instability is fully suppressed at 40 nm sample. • Cutting and kink-like shear bandings prevail respectively at large and small scales. [ABSTRACT FROM AUTHOR]

[Display omitted] • Anthracene-appended poly(ʟ-lactide)s (AAP) were synthesized by ROP of ʟ-lactide. • The excimer emission was observed in the low molecular weight AAP. • The monomeric emission is observed in amorphous and single crystals of AAP. • In crystallized AAP, fluorescence arises from anthracene excimers and monomers. • In the gel state AAP (e form), only the excimer emission was observed. The design and development of solid-state excimer-emitters bear great potential for attaining efficient solid-state luminescent materials. In this study, we have synthesized anthracene-appended poly(ʟ-lactide)s (AAPs) to regulate the arrangement of anthracene moieties by controlling the crystallization and polymorphic form of covalently linked poly(ʟ-lactide) (PLLA). In the high molecular weight AAP, the fluorescence intensity mainly arises from the monomeric anthracene moieties, whereas in the low molecular weight AAP, the excimer emission was observed depending on the structure and morphology of covalently-linked PLLA. The monomeric emission is predominantly observed in amorphous polymer due to the molecular level dispersion of covalently-linked anthracene moieties throughout the polymer matrix. When the polymer was crystallized under different conditions, covalently-linked anthracene moieties were excluded from polymer crystals or crystalline lamellae and are located on the surface or at the interface, which is advantageous for regulating the geometry of anthracene moieties. In the case of single crystals of PLLA, covalently-linked anthracene moieties assemble on the surface and emit mainly in their monomeric state due to the lack of π-stacking. In the melt-crystallized sample (α form), covalently-linked anthracene moieties reside at the interface of crystalline and amorphous domains by either dipolar interactions or π-stacking and fluorescence arising from anthracene excimers and monomers. In the gel state (ε form), only the excimer emission was observed due to the effective interactions between the anthracene moieties in the presence of excess solvent in the amorphous domains. In this way, polymer crystallization played a significant role in determining the arrangement of covalently-linked anthracene moieties in AAP. This study reveals the role of polymer crystallization on the excimer evolution in fluorophore-appended semicrystalline polymers and provides new insight into the design and development of fluorophore-appended polymers for optoelectronic devices. [ABSTRACT FROM AUTHOR]

• A method for developing models of realistic CASS microstructure is shown. • Simulated sound fields in CASS models agree well with experimental sound fields. • Simplified CASS models using Voronoi regions outperformed the realistic CASS models. • Large variations in echo amplitude were observed when randomizing the CASS model microstructure. Ultrasonic inspection of cast austenitic stainless steel (CASS) in the nuclear industry is particularly challenging because of sound field scatter and attenuation caused by the coarse-grained microstructure. Modeling and simulation are important tools in ultrasonic testing, as they can be used to help address key aspects of inspections, such as developing new probe designs, predicting inspection reliability, and testing phased-array focal laws. However, developing a useful and reliable CASS model is challenging due to the many grain interfaces and crystalline orientations that must be captured. We demonstrate a method of creating a realistic CASS model that is usable in CIVA, a commercially available modeling and simulation software platform. Using polished and chemically etched sections to highlight the grain structure and orientation, we generate models of a coarse-grained equiaxed specimen and a columnar specimen. We also test an alternative method of generating a coarse-grained model using Voronoi regions. We qualitatively compare sound field scatter and quantitatively compare sound field attenuation and beam partitioning in simulated sound fields to those of laboratory-measured sound fields. Results show that the Voronoi models perform as well as or better than the models based on actual grain morphology. We also show that model-to-model randomness in Voronoi grain structure can impact the magnitude of a simulated echo response by a factor of two or more. Although CASS models are potentially a good depiction of reality for a given scenario, they should not be considered representative since CASS morphology can change significantly from specimen to specimen or within the same specimen. [ABSTRACT FROM AUTHOR]

Bismuth telluride-based thermoelectric (TE) devices were widely used in waste heat recovery due to their high thermoelectric figure of merit (ZT), but the severe diffusion between Sn-based solder and TE pillar generated porous and brittle Sn-Te intermetallic compound (IMC), which seriously restricted the reliable service of devices. Ni-based coating was used but the thick Ni-Te IMC also impaired the properties of TE pillars. In this work, the crystalline Co-P coating was inserted between the p-type TE material Bi 0.5 Sb 1.5 Te 3 and the solder by electrodeposition, and the power generation sustainability of the TE pillar were significantly improved, and the mechanism was revealed. The microstructural characterization proved that the Co-P coating could effectively resist the diffusion of active Sn, Bi, Sb, Cu atoms. Co-P coating would provide support for the structural integrity and performance sustainability of TE pillars. It was worth noting that an ultrathin CoTe 2 IMC layer was formed between the Co-P coating and the Bi-Sb-Te pillar, which was much thinner than the Ni-Te IMC layer reported in the literature. This indicated that Co-P only consumed little thermoelectric elements, but also a good metallurgical bond was formed between the Co-P and the Bi-Sb-Te. After aging at 423 K for 150 h, the maximum output power and average Seebeck coefficient of the TE pillar without coating dropped significantly by 74% and 34%, respectively, and the internal resistance rose by 67%. Remarkably, the maximum output power and average Seebeck coefficient of the TE pillar protected by the Co-P coating only decreased by 14% and 5%, respectively, and the internal resistance only increased by 6%. [Display omitted] • Co-P coating showed a remarkable effect on the sustainability of TE power generation. • Co-P coating could effectively resist the diffusion of active Sn, Bi, Sb, Cu atoms. • An ultrathin CoTe 2 IMC layer was formed between the Co-P coating and the TE pillar. • Co-P coating consumed less thermoelectric elements than Ni-based coating. [ABSTRACT FROM AUTHOR]

[Display omitted] • The crystallization process of amorphous YAG oxide is investigated from an atomic point of view. • The crystallization proceeds on the surface and interior of the amorphous YAG separately, and which show the preferential crystallization of the surface atoms. • Some atoms in the amorphous phase were controlled by the periodic potential field of the crystal atoms and produced dynamically changing semi-ordered structures at the amorphous/crystalline interface with mainly concentrated within 1–2 nm from the interface. The transformation from amorphous materials to crystals and the corresponding microscopic mechanism have become a research focus in materials science, condensed matter physics, and biophysics etc. In this paper, taking Y 3 Al 5 O 12 (YAG) as an example, the crystallization process of amorphous YAG oxide is investigated from an atomic point of view through the combination of spherical aberration-corrected transmission electron microscopy (SCTEM) with an in situ heating method, and the morphology and structural evolution of the surface and interface are explored. It is observed that the crystallization proceeds on the surface and interior of the amorphous YAG separately. Through atomic-scale imaging, it is determined that semi-ordered structures are formed in a few atomic layers at the amorphous/crystalline interface and that the structural transformation process from the amorphous to the semi-ordered state and then to the crystal structure may be the main reason for the multiple stages of the crystallization of amorphous oxides. This study demonstrates the mechanism of the amorphous-to-crystal transformation on the atomic scale and contributes to gaining a better understanding of the crystallization process of bulk oxides, especially complex metal oxides. [ABSTRACT FROM AUTHOR]

Nano-porosity in amorphous Ge formed by swift heavy ion irradiation displays a peculiar self-organisation process. Initially almost randomly distributed pores grow with increasing irradiation fluence and segregate in layers orientated parallel to the sample surface. This self-organisation mechanism depends on the ion energy, thickness of the amorphous Ge layer and the angle of ion incidence and shows a characteristic length depending on ion energy and irradiation angle. Molecular dynamics simulations of individual ion tracks show that voids form due to the transition from the low-density amorphous to the high-density liquid phase, which also gives rise to a flow directed away from large pores and surfaces. The flow results in a characteristic distance from surfaces and larger pores, below which new voids do not form, and supports the formation of voids at the amorphous/crystalline interface. Simulations also demonstrate that, while direct impacts can reposition small voids, partial or nearby impacts promote their growth at the same location. These processes are plausible drivers for the self-organization. [Display omitted] [ABSTRACT FROM AUTHOR]

Making composites with crystalline inclusions can improve plasticity in brittle metallic glasses. In this study, we show a new metallic glass matrix composite designed with a gradient network architecture made of amorphous matrix regions and gradient crystalline network regions. Using molecular dynamics simulations, we validated theoretically the hypothesized concept of this new composite. Our results show that the unique microstructure leads to significant strain delocalization which can delay the generation of catastrophic shear bands. This is resulted from the new mechanism by both forming diffuse embryonic shear bands in the thin crystalline network interface and hindering or guiding their formation and movement in thick crystalline network regions with the presence of internal stresses generated from the gradient. This work demonstrates the synergistic effects induced by the heterogeneous gradient network design in the mechanical properties of metallic glass matrix composites and may open up exciting new possibilities. Macroscopic plasticity can be improved by spatially patterning heterogeneity into "microstructures" in the homogeneous structure-less amorphous metals. By further introducing gradients in the microstructure, we can elevate the improvement to a new level. Here, we show a new metallic glass matrix composite designed with a gradient network architecture made of amorphous matrix regions and gradient crystalline boundary network regions (a). The designed gradient structure can greatly enhance the plasticity as compared to the monolithic metallic glass (MG) and nanoglass (NG) (b). The new design of the MG composite creates a hierarchical heterostructure in the spatial pattern that can effectively cause delocalization of local shear (c) and the significant delay of brittle fracture. [Display omitted] [ABSTRACT FROM AUTHOR]

Pickering emulsions, stabilized by solid particles at the oil/water interface, are brought into focus due to their long‐term stability additional functionality and higher safety. Cyclodextrins are enzymatic derivatives of starch which have a hydrophobic inside cavity and a hydrophilic outside surface. Cyclodextrins aggregate and form crystalline nanoparticles at the interface of oil/water by self‐assembly which adsorbs on the surface of oil droplets to maintain the long‐term stability of the emulsion during the emulsifying process. Moreover, Cyclodextrins can form amphiphilic complex supermolecules nanoparticles with lipophilic molecules and be utilized to prepare functional Pickering emulsions owing to the appropriate size, reasonable structure, human edible, and environmentally benign. The review compiles and assesses the properties of cyclodextrins and the latest advances on preparations, characterizations, mechanisms and applications of Pickering emulsions stabilized by cyclodextrin nanoparticles. The results will help to deeply understand the structure and function relationship and expand the application of Pickering emulsion in various fields. [ABSTRACT FROM AUTHOR]

The concave behaviour of the Porod invariant observed during the calcination of CaCO3 powder samples suggests the following picture of the evolving internal structure of the samples. The outset sample is formed by a crystalline CaCO3 phase and a void phase. During the calcination, the first phase shrinks in volume at fixed density since the temperature increase breaks down the crystalline structure at the interface, leading to the formation of an amorphous phase comprising an equal number of CO2 and CaO atomic groups. The last groups gradually condense, forming a third phase of solid CaO of constant density and increasing volume fraction, while the companion CO2 groups flow out of the sample. The amorphous phase occupies, with a variable density, all the volume left free by the other two phases. At the end of the calcination, both the volume fraction of the first phase and the density of the amorphous phase vanish so that the sample will again be made up of two phases: the voids and the solid CaO. Best‐fitting the resulting theoretical expressions of the Porod invariant and of the Porod law coefficient to the observed values, one can determine the matter densities, volume fractions and specific surface areas of the phases. [ABSTRACT FROM AUTHOR]

The development of ethanol electrooxidation catalysts with high activity and robust stability is essential for the commercialization of direct ethanol fuel cells. However, because of their low C1 selectivity, the electrocatalytic efficiency of catalysts for complete ethanol oxidation is still far from satisfying. Herein, a novel 2D Pd--Au heterogeneous catalyst for enhancing C1 selectivity to achieve highly efficient ethanol oxidation through phase and interphase engineering is designed. It is found that owing to the plentiful amorphous/crystalline interphases, the selectivity of C1 pathway on Pd--Au heterocatalyst can be improved up to 33.2% at a low potential, 10.4 times higher than commercial Pd/C (3.2%). Furthermore, 89.1% of initial mass activity of Pd--Au HNS can be retained after the accelerated degradation test of 2000 potential cycles, much higher than those of Pd NS (39.3%), commercial Pd/C (34.4%), and Pt/C (11.4%). The CO stripping and in situ Fourier transform infrared experiments reveal that 2D Pd--Au heterocatalyst, with intricate design of the amorphous Pd domain and the crystalline Au cluster interface, has better antipoisoning properties and stronger C--C bond cleavage ability than pure Pd nanosheets. Density functional theory calculations further demonstrate that the introduction of Au clusters switches on the electroactivity of amorphous Pd as the electron pump to accomplish the complete oxidation of ethanol, in which the selectivity for C1 pathway is significantly boosted whereas the typical C2 pathway is substantially blocked. [ABSTRACT FROM AUTHOR]

The shear of a crystalline interface by a matrix dislocation is an elementary phenomenon of plasticity that generates a three-dimensional elastic field difficult to express. However, in the case of a flat interface and two elastic isotropic media, the present work shows that this field can be described starting from an explicit form of the Green tensor associated with a point force exerted in one of the crystals. Indeed, the knowledge of this tensor makes it possible to express the displacement field of a dislocation in the final form of a surface integral. Because the shear is limited by a matrix branch and an interfacial branch, the dislocation can be called 'hybrid dislocation' or HD. If the two branches are straight, the field is that of an angular HD. Moreover, if the crystals are identical, the field becomes that of an angular matrix dislocation whose field is well known since Yoffe (1960). By applying the superimposition theorem, it becomes possible to determine the field of more complex configurations, such as those sometimes observed during the transmission of the plastic slip through the interfaces. [ABSTRACT FROM AUTHOR]

Mathematical analysis is performed to examine the reflection and transmission phenomena of plane waves at the corrugated interface of crystalline structure separating two distinct monoclinic thermoelastic media. Analysis of this phenomena is achieved adopting classical dynamic coupled, Lord–Shulman, and Green–Lindsay theories. Using Rayleigh's methods, the expressions of reflection and transmission coefficients of reflected and transmitted waves are deduced for the case of corrugated as well as plane interfaces. The influence of corrugation and frequency parameters on reflection and transmission coefficients for all three theories has been extensively analyzed with a comparative approach. Findings of the study are demonstrated through numerical and graphical results. Furthermore, the obtained result is validated with the preexisting result. [ABSTRACT FROM AUTHOR]

Coarse-grained descriptions of dislocation motion in crystalline metals inherently represent a loss of information regarding dislocation-dislocation interactions. In the present work, we consider a coarse-graining framework capable of re-capturing these interactions by means of the dislocation-dislocation correlation functions. The framework depends on a convolution length to define slip-system-specific dislocation densities. Following a statistical definition of this coarse-graining process, we define a spatial correlation function which will allow the arrangement of the discrete line system at two points—and thus the strength of their interactions at short range—to be recaptured into a mean field description of dislocation dynamics. Through a statistical homogeneity argument, we present a method of evaluating this correlation function from discrete dislocation dynamics simulations. Finally, results of this evaluation are shown in the form of the correlation of dislocation densities on the same slip-system. These correlation functions are seen to depend weakly on plastic strain, and in turn, the dislocation density, but are seen to depend strongly on the convolution length. Implications of these correlation functions in regard to continuum dislocation dynamics as well as future directions of investigation are also discussed. [ABSTRACT FROM AUTHOR]

In this work, the irreversible effects of an applied electric field on the magnetotransport properties of LaAlO3/SrTiO3 conducting interfaces are investigated, with focus on their multiband character. Samples of different types, namely with either crystalline or amorphous LaAlO3 overlayer, are studied. The two‐band analysis highlights the similarity of the electronic properties of crystalline and amorphous interfaces, regardless much different carrier densities and mobilities. Furthermore, filling and depletion of the two bands follow very similar patterns, at least in qualitative terms, in the two types of samples. In agreement with previous works on crystalline interfaces, it is observed that an irreversible charge depletion takes place after application of a first positive back gate voltage step. Such charge depletion affects much more, in relative terms, the higher and three‐dimensional dyz, dzx bands than the lower and bidimensional dxy, driving the system through the Lifshitz transition from two‐band to single band behavior. The quantitative analysis of experimental data evidences the roles of disorder, apparent in the depletion regime, and temperature. Noteworthy, filling and depletion of the two bands follow very similar patterns in crystalline and amorphous samples, at least in qualitative terms, regardless much different carrier densities and mobilities. [ABSTRACT FROM AUTHOR]

Solid-phase epitaxy (SPE) and other three-dimensional epitaxial crystallization processes pose challenging structural and chemical characterization problems. The concentration of defects, the spatial distribution of elastic strain, and the chemical state of ions each vary with nanoscale characteristic length scales and depend sensitively on the gas environment and elastic boundary conditions during growth. The lateral or three-dimensional propagation of crystalline interfaces in SPE has nanoscale or submicrometer characteristic distances during typical crystallization times. An in situ synchrotron hard x-ray instrument allows these features to be studied during deposition and crystallization using diffraction, resonant scattering, nanobeam and coherent diffraction imaging, and reflectivity. The instrument incorporates a compact deposition system allowing the use of short-working-distance x-ray focusing optics. Layers are deposited using radio-frequency magnetron sputtering and evaporation sources. The deposition system provides control of the gas atmosphere and sample temperature. The sample is positioned using a stable mechanical design to minimize vibration and drift and employs precise translation stages to enable nanobeam experiments. Results of in situ x-ray characterization of the amorphous thin film deposition process for a SrTiO3/BaTiO3 multilayer illustrate implementation of this instrument. [ABSTRACT FROM AUTHOR]

Poor plasticity and small dimension are the main disadvantages of metallic glass. Diffusion bonding and composite fabrication between bulk metallic glasses (BMGs) and crystal metal are promising methods of addressing these disadvantages. In this study, the long‐term atomic diffusion behavior in the glass transition temperature (Tg) is investigated to avoid the formation of the crystalline phase at the interface. Diffusion‐coupled Ni/Zr48Cu36Ag8Al8 BMG is successfully fabricated by sputtering deposition. The diffusivities of Ni in Zr48Cu36Ag8Al8 metallic glass are calculated by using the thin‐film solution of Fick's second law. The diffusivities of Ni in Zr48Cu36Ag8Al8 alloy are functions of annealing temperature and time because of the dominant effect of the free volume. High‐resolution transmission electron microscopy results show that there are no crystals formed at the interface of diffusion‐coupled Ni/Zr48Cu36Ag8Al8 BMG below Tg, and mutual element diffusion occurs near the interface. Analysis of the diffusion behavior and microstructure indicates that the long‐term annealing below Tg can be applied to the diffusion bonding of BMG and crystal metal. [ABSTRACT FROM AUTHOR]

Recently, the crystallographic phases of HfO2 and ZrO2, including the polar phases, have been well characterized, and also the total and free energies have been calculated. However, less is known about the structure and energy of the crystalline coherent interface—also called the interphase. The formation of domain and phase boundaries is determined by interphase energies and properties, and their knowledge is indispensable to better understand the phase formation and phase stability. We have calculated the interphase energy for HfO2 and ZrO2 at T = 0 K for the relevant phase pairs with two methods, which are in good agreement. The method is applicable to any crystalline material with metastable phases. The values range in a few 100 mJ/m2, which is consistent with previous estimates from room temperature but too large for estimates from high-temperature processes. We propose a temperature dependence of interphase energy such that it becomes small close to the phase transition. [ABSTRACT FROM AUTHOR]

An analytical investigation performed on Southern Italy pottery highlighted the usefulness of Raman spectroscopy to give answers to archaeological questions. It can provide important information concerning the production technology and raw materials constituting the glassy coatings. Raman spectroscopy was supported by Scanning Electron Microscopy coupled with Energy Dispersive X‐ray Spectroscopy (SEM‐EDS) for observations and elemental analysis. The studied samples, ranging from the 13th century lead‐tin‐glazed protomajolica to the 15th –16th enamelled pottery, come from the Castles of Montella and Ariano Irpino (Campania), from the castles of Scicli and Modica and from surveys carried out in Buscemi and Caltagirone (Sicily). Glassy matrices, opacifying agents, colour‐related raw materials and body‐coating interface crystalline phases were investigated. Though the coatings resulted all typically lead‐rich glass types, lumps showing a different Raman profile suggested that at least in one case, the batch was adultered with recycled glass waste. Furthermore, samples coming from Montella, belonging to the three main classes of ceramics defined by archaeological hypothesis, could be grouped according to their cassiterite content. The crystallization of lead–potassium feldspars at the coating‐body interface in a group of samples was ascertained. With regard to the origin of colours, the spectra of blue coatings highlighted phases that can be traced back to the use of Co‐based and Co–As‐based raw materials, while turquoise decorations were found to contain malayaite. Highlights: Medieval and renaissance pottery from Southern Italy were analysed.Raman analyses provided unexpected results and answers to archaeological questions.SnO2 Raman bands confirmed the grouping of Montella samples in three classes.Neoformed phases due to reactions during the production processes were discovered.Different cobalt‐based phases were found in the blue enamels. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cells (SOFC) convert chemical energy from hydrogen, methane, or other hydrocarbons directly into electrical energy and heat. Advantages are low noise during operation as well as relatively low pollutant emissions. This makes them interesting for stationary applications, eg combined heat and power plants for domestic use and for mobile applications, when there is a demand for integrating auxiliary power units. The high operating temperatures of about 850°C and the simultaneous presence by both, reducing and oxidizing atmospheres place high demands on the components of a SOFC. Due to these requirements, glass‐ceramics are proposed as sealants between interconnector and electrolyte. They provide lower costs and lower weight than commercially used silver solders. Furthermore, they have the following impressive benefits: The sealants are electrical insulating, chemical stable and by careful materials selection and adapted manufacturing processes, they adhere well on steel and on ceramic substrates. In order to characterize the adhesion of glass‐ceramic sealants on steel and on zirconia substrates, layer‐like composites are fabricated by screen‐printing and subsequent sintering in air. It turns out that the formation of crystalline phases at the interface is crucial for the adhesion behavior. [ABSTRACT FROM AUTHOR]

Order/dis-order atomic arrangements in crystalline/amorphous structure possess a complementing effect in electro-catalysis as the former one can offer a long-range electronic conducting path, whereas the latter is rich with active sites. However, atomic level interfacing of crystalline and amorphous structures is extremely challenging and thus often end-up with uncontrolled secondary deposition one above another. Here, we are reporting second-scale atomic rearrangement of crystalline oxide nanowire surface into amorphous molybdenum sulfide shell that displayed excellent hydrogen evolution activity. Employing transient heating by microwave-activated graphene filament, surface atoms of molybdenum tungsten oxide (MoWO) nanowire can be arrested in either an amorphous or crystalline state during their sulfidation. Such a nanowire structure consisting of crystalline oxide core-amorphous sulfide shell shows excellent catalytic activity for hydrogen evolution reaction (HER) and exhibits an overpotential of 136 mV at 10 mA cm−2 in the acid electrolyte, which is much lower than the overpotential of parent oxide nanowire (356 mV) and its fully sulfurized crystalline counterpart (163 mV). As-developed catalyst also shows competitive HER performance with excellent alkaline and neutral electrolytes stability, thereby qualifying it as a pH universal catalyst. A detailed density functional theory calculation reveals oxide core promoted activation of multiple sites of amorphous sulfide phase, which provide key insights of electronic modulation via crystalline/amorphous interfacial structure for HER catalysis. This rapid and highly facile technique can lay the platform for the development of generic crystalline/amorphous core-shell nanostructure and their possible use as cost-effective and efficient catalysts. [Display omitted] • The unique microwave-induced second-scale surface amorphization is demonstrated. • Amorphous@crystalline core-shell nanowire of a-MoS x @MoWO structure was realized. • The a-MoS x @MoWO exhibits excellent pH-universal HER activity. • Synergy between core and shell for HER is studied by detailed DFT calculation. • Crystalline core turns multiple inactive sites of amorphous shell to highly active. [ABSTRACT FROM AUTHOR]

[Display omitted] • High-entropy alloy nanolaminates are obtained. • The coherent interface in nanolaminates is designed to improve ductility. • The crystalline/amorphous hierarchical nanostructure is designed to enhance strength. Introducing nanolaminates structure is a promising strategy to obtain the controllable microstructure and mechanical properties of high entropy alloy (HEA). In this work, the Al 0.5 CoCrFeNi/CoCrCuFeNi nanolaminates with coherent interface and crystalline/amorphous hierarchical nanostructure was designed. On the one hand, the coherent interface with continuous slip direction and planes enables nanolaminates with great deformability. On the other hand, the hierarchical nanostructure in the nanolaminates contributes to high strength via the interaction between crystalline and amorphous structures. Microstructural observations indicated that abundant nanotwins and stack faults were filled in the columnar nanocrystalline cutting across the interface, leading to a high hardness due to the dislocation-interface interactions. The results of nanoindentation tests revealed that the hardness of the nanolaminates up to 8.02 GPa, which markedly exceeds many HEA films with face-centered cubic (FCC) phase. The findings provide a new avenue for improving the mechanical properties of HEA nanolaminates in a controllable manner. [ABSTRACT FROM AUTHOR]

Transition metal borides have shown great promise as a supercapacitor electrode material. However, the amorphous structure of metal borides leads to the structural collapse of electrode material during electrochemical cycling, which seriously affects the stability of the material. In the present work, we successfully construct amorphous/crystalline NiCoB@NiCo 2 S 4 heterogeneous interfacial composites by introducing the outer layer of sulfide to improve the electrochemical performance. NiCoB@NiCo 2 S 4 shows a specific capacitance of 1562 F g−1 at a current density of 1 A g−1 and still possesses 58% specific capacitance even at a higher current density of 50 A g−1. The asymmetric supercapacitor (ASC) device assembled with Bi 2 O 3 @C as the negative electrode and NiCoB@NiCo 2 S 4 as the positive exhibits a high energy density of 98.75 Wh kg−1 at a power density of 750 W kg−1. The ASC also exhibits excellent cycling stability with capacitance retention of 118% after 10000 cycles at a current density of 10 A g−1, which fully demonstrates the practical applications value of NiCoB@NiCo 2 S 4 //Bi 2 O 3 @C. The amorphous/crystalline NiCoB@NiCo 2 S 4 heterogeneous interfacial composites were successfully constructed for the first time. The resulting amorphous/crystalline heterogeneous interface effectively improves the electron/ion transport rate and increases the electrochemical reactive sites. The assembled NiCoB@NiCo 2 S 4 //Bi 2 O 3 @C asymmetric supercapacitors exhibit a high energy density of 98.75 Wh kg−1 due to the high specific capacitance potential of NiCoB@NiCo 2 S 4 and Bi 2 O 3 @C. The introduced crystalline outer cladding metal sulfide effectively inhibits the oxidation of the metal boride core, thus exhibiting excellent electrochemical cycling stability. [Display omitted] • Amorphous/crystalline NiCoB@NiCo 2 S 4 interface structure was firstly constructed. • NiCoB@NiCo 2 S 4 showed 1562 F g−1 at 1 A g−1. • The ASC had a high energy density of 98.75 Wh kg−1. [ABSTRACT FROM AUTHOR]

Microstructures and mechanical properties of Ni matrix composites reinforced with amorphous SiO 2 particles by in-situ pyrolysis of polycarbosilane (PCS) coated on Ni powders were studied in this paper. The submicron spherical amorphous SiO 2 particles instead of traditional SiC uniformly distributing in the composites result from the generated silicon source by PCS pyrolysis combined with oxygen impurity in the preparation. The prepared composites achieve high yield strength, 172 MPa, and ultimate tensile strength, 494 MPa, as well as outstanding ductility, total elongation 28.4 %, which is improved 13.9 %, 50.6 % and 160.6 % compared with those for pure Ni samples, respectively. The effects of solid solution strengthening, grain refinement strengthening, reinforcement particle strengthening and dislocations behavior of at amorphous/crystalline interface on the combination of high strength and ductility of the composites were discussed. [Display omitted] • Amorphous SiO 2 reinforced Ni matrix composites were fabricated by in-situ pyrolysis of polycarbosilane coated on Ni powders. • Amorphous SiO 2 instead of crystalline SiC formed by the combination of silicon generated in the pyrolysis with oxygen. • The composites exhibit a combination of excellent tensile strength and ductility. [ABSTRACT FROM AUTHOR]

Developing earth-abundant, efficient and durable catalysts toward the hydrogen evolution reaction (HER) is critical for the large-scale deployment of sustainable hydrogen production from renewable energies. Transition metal dichalcogenides (TMDs) are promising candidates for the replacement of precious and state-of-the-art platinum-groups-metals, but their HER performance still needs improvement. Constructing crystalline/amorphous interfaces is effective in terms of creating abundant active sites for boosted catalytic activity. Therefore, in this study, defective crystalline vanadium disulfide/amorphous molybdenum sulfide/reduced graphene oxide (c-VS 2 /a-MoS x /RGO) nanocomposites are fabricated via a combined hydrothermal-plasma method. The HER performance of c-VS 2 /a-MoS x /RGO is optimized by tuning the plasma treatment duration and the amount of precursors, and the corresponding mechanisms were investigated by morphological and elemental analyses. Taking advantage of the high reactivity of low-temperature plasma, the strategy presented in this work is effective in terms of constructing crystalline/amorphous interfaces and introducing multiple defects, which creates abundant active sites and ultimately results in boosted HER performance. The optimal c-20VS 2 /a-40MoS x /RGO catalyst exhibited excellent HER activity (η@100 mA cm−2 = 193 mV and η@500 mA cm−2 = 244 mV) and good stability. This work provides a facile and effective strategy for promoting the HER performance of TMDs and sheds light on rationally designing efficient HER catalysts using earth-abundant elements. [Display omitted] This work describes a combined hydrothermal-plasma method for fabricating defective crystalline vanadium disulfide/amorphous molybdenum sulfide/reduced graphene oxide (c-VS 2 /a-MoS x /RGO) nanocomposites toward hydrogen evolution reaction. The HER activity of c-VS 2 /a-MoS x /RGO can be optimized by adjusting plasma treatment duration and the amount of precursors. Structural and electrochemical characterizations indicate that the optimal c-VS 2 /a-MoS x /RGO catalyst possess abundant active sites, which can be attributed to crystalline/amorphous interface and multiple defects in the heterostructures. The c-VS 2 /a-MoS x /RGO catalysts show excellent activity and good stability for the HER. • This work develops a method for constructing crystalline/amorphous interfaces. • Crystalline/amorphous interfaces are beneficial for boosting HER activity. • The level of lattice defects should be controlled for optimal HER activity. • c-VS 2 /a-MoS x /RGO exhibits boosted HER performance at high current densities. [ABSTRACT FROM AUTHOR]

Although the synthesis of amorphous/crystalline heterojunction is still difficult due to thermodynamic instability, the introduction of amorphous components not only avoids lattice mismatch but also triggers higher photoelectric activity at the interface, making it particularly attractive. Herein, a novel amorphous ZnO/crystalline N-TiO 2 heterojunction (aZn/NT) was firstly synthesized by a simple one-pot synthesis process. Non-specific preparation conditions and inexpensive raw materials [e.g., zinc acetate, bis(ammonium lactate) titanium hydroxide (TALH) and citric acid] are significant indicators of this method. The systematic test shows that the hydrolysis of TALH is independent and precedes the substitution reaction of citric acid to form a composite spherical structure. Different testing methods have shown that the newly formed bonds (Ti-O-N-Zn or Ti-N-O-Zn) between the two components during the hydrothermal process are the basis of the heterostructure association. Moreover, the combination of positively charged surfaces, abundant oxygen vacancy defects, and transport channels accelerates the photoreduction of Cr(VI) on aZn/NT surface. The high catalytic rate [0.022 min−1 for 200 mg L−1 Cr(VI)] and low activity loss rate (∼2.3% within 5 cycles) under optimal conditions indicate that the synthesis of highly active heterogeneous materials can be achieved through a simple path. [Display omitted] • A new type of amorphous/crystalline heterojunction interface has been simply constructed. • The interface structure changes the photoelectric properties and interfacial adsorption behavior of composite materials. • The metal oxygen bridge bonding effect, oxygen vacanciesand surface positive charges support the rapid reduction of Cr(VI). [ABSTRACT FROM AUTHOR]

It is demonstrated that a lamellar crystalline structure may form near the metal–polymer interface during the comolding of metal–thermoplastic joints. The influence of the crystalline morphology near the interface on the rupture behavior of the joint is studied experimentally. High‐resolution scanning electron microscopy (HR–SEM), atomic force microscopy (AFM), and optical microscopy are used to characterize the microstructure of the metal–thermoplastic interface. The results show that a lamellar crystalline structure at the interface promotes cohesive failure, i.e., the crack runs in the polymer. Additional experiments show that a transcrystalline polymer structure at the interface results in failure at the interface. Herein, two methodologies have been developed to characterize the formation of the transcrystalline polymer interphase structure based on X‐ray diffraction and polarized light hot stage microscopy. The results show the importance of the polymer interphase structure for metal–thermoplastic interactions. Understanding of the formation of the polymer interphase and its influence on the interfacial bonding strength are vital for thermoplastic applications such as fiber‐reinforced thermoplastic composites, tool surface design for processing of thermoplastics, and their composites as well as for metal–polymer hybrid joints. [ABSTRACT FROM AUTHOR]

A variational model to simultaneously treat Stress-Driven Rearrangement Instabilities, such as boundary discontinuities, internal cracks, external filaments, edge delamination, wetting, and brittle fractures, is introduced. The model is characterized by an energy displaying both elastic and surface terms, and allows for a unified treatment of a wide range of settings, from epitaxially-strained thin films to crystalline cavities, and from capillarity problems to fracture models. The existence of minimizing configurations is established by adopting the direct method of the Calculus of Variations. The compactness of energy-equibounded sequences and energy lower semicontinuity are shown with respect to a proper selected topology in a class of admissible configurations that extends the classes previously considered in the literature. In particular, graph-like constraints previously considered for the setting of thin films and crystalline cavities are substituted by the more general assumption that the free crystalline interface is the boundary, consisting of an at most fixed finite number m of connected components, of sets of finite perimeter. Finally, it is shown that, as m → ∞ , the energy of minimal admissible configurations tends to the minimum energy in the general class of configurations without the bound on the number of connected components for the free interface. [ABSTRACT FROM AUTHOR]

THz and DC losses in crystalline states of GeSbTe and AgInSbTe phase-change material systems are re-examined and discussed. Although a simple free carrier transport has been assumed so far in the GeSbTe (GST) system, it is shown through recent experimental results that a series sequence of intragrain and intergrain (tunneling) transport, as recently formulated in Shimakawa et al., 'The origin of non-Drude terahertz conductivity in nanomaterials,' Appl. Phys. Lett. 100, 132102 (2012) may dominate the electronic transport in the commercially utilized GST system, producing a non-Drude THz conductivity. The extracted physical parameters such as the free-carrier density and mobility are significantly different from those obtained from the Drude law. These physical parameters are consistent with those obtained from the DC loss data, and provide further support for the model. Negative temperature coefficient of resistivity is found even in the metallic state, similar to amorphous metals, when the mean free path is short. It is shown that the concept of minimum metallic conductivity, often used in the metal-insulator transition, cannot be applied to electronic transport in these materials. [ABSTRACT FROM AUTHOR]

We present a density functional theory study of the oxidation of 1D periodic rods supported along the [001] direction on the rutile TiO2(110) surface. The study shows evidence for an oxidation of the interface between the supported Au and the TiO2 crystal. The added O atoms adsorb at the 5f-Ti atoms in the through under the Au rod and are stabilized by charge transfer from the nearest Au atoms. Despite an extensive search, we find no low energy barrier pathways for CO oxidation involving CO adsorbed on Au and O at the perimeter of the Au/TiO2 interface. This is in part attributed the weak adsorption of CO on cationic Au at the perimeter. [ABSTRACT FROM AUTHOR]

Ultrathin layers of hydrogenated amorphous silicon (a‐Si:H), passivating the surface of crystalline silicon (c‐Si), are key enablers for high‐efficiency silicon heterojunction solar cells. In this work, the authors apply highly sensitive attenuated total reflectance Fourier‐transform infrared spectroscopy, combined with carrier‐lifetime measurements and carrier‐lifetime imaging, to resolve several fundamental and technology‐related questions related to the a‐Si:H/c‐Si interface. To gain insight, the a‐Si:H/c‐Si interfacial morphology is intentionally manipulated by applying different surface, annealing and ageing treatments. Changes are observed in the vibrational modes of hydrides (SiHX), oxides (SiHX(SiYOZ)) together with hydroxyl and hydrocarbon surface groups. The effect of unintentional oxidation and contamination is considered as well. Electronic interfacial properties are reviewed and discussed of hydrogen mono‐layer passivation of the c‐Si surface and from the perspectives of a‐Si:H bulk properties. It is found that both models have severe limitations and suggest that a new physical model of the interface, considering both is required. [ABSTRACT FROM AUTHOR]

The transfer of plastic sliding through a crystalline interface involves at least a dislocation having a branch in each crystal. The elastic field associated with this elemental configuration has been processed in the past by Belov et al. (1983, 1992) but has never been verified or used, to the author's knowledge. With typographical corrections and various verifications, the results obtained in this work confirm the validity of the theory for isotropic and/or anisotropic crystals. A general explicit solution to the elastic field is derived in the case of two different isotropic crystals. The theory fails when one branch is along the interface while the other lies in a crystal (hybrid dislocation). On the other hand, if a branch is very little inclined relative to the interface (quasi-hybrid dislocation), the theory applies fully. In this context, the combination of two quasi-hybrid dislocations solves in practice the problem of the triple node anchored to the interface. [ABSTRACT FROM AUTHOR]

Two‐dimensional electron gas (2DEG) formed at the interface of perovskite oxides has drawn considerable interest due to its rich underlying physics and potential in future generation spin‐electronic devices. Electrostatic gating and light illumination are two frequently applied stimuli for such devices. In this work, electrical conductivity tuning of a recently discovered conducting interface of crystalline LaVO3 and KTaO3 (LVO−KTO) is reported through electrostatic gating as well as light illumination. Signature of significant photoconductivity as well as persistent photocurrent is observed. A giant enhancement of resistance is found to occur under light illumination when a negative electrostatic gate bias (VG > −8 V) is applied. These effects offer a possible control on carrier density of the oxide interface, which is otherwise difficult due to their huge intrinsic carrier density. Further, a protocol deploying light and gate bias in an appropriate sequence is demonstrated to use this interface as a possible optical‐switch or memory storage device. [ABSTRACT FROM AUTHOR]

An amorphous/crystalline metallic composite (A/C-MC) integrates metallic glass with crystalline metals in one system. The amorphous-crystalline interface (ACI) in A/C-MCs under deformation absorbs dislocations and may fundamentally change the dilemma that the strength comes at the expense of the ductility of a material. However, the development of such materials is still at a trial and error stage due to the lack of a clear-cut understanding on how the amorphous component become instable when a dislocation-mediated plasticity flows into the glassy phases. To meet this need, here we focus on gaining the physical insights into the dislocation-ACI reaction in A/C-MCs through atomistic simulations. We have (i) digitally resembled an interface structure close to that in experiments by annealing melted metallic glasses at cooling rates as low as ∼ 104 K/s; (ii) correlated the dislocation absorption events with the activation of shear transformation zones (STZs) in A/C-MCs under a plastic shear; (iii) identified the mechanisms responsible for a continuous dislocation absorption-induced instability in glassy phases; (iv) calibrated a set of constitutive relations, kinetic rules, and model parameters that can be used in an effective temperature concept-based STZ theories at the continuum level; and (v) characterized the local stress states ahead of the instability band and lay the macroscopic-level glass instability criterion on a firm atomistic basis. Our major findings are: (a) there exists a nanoscale structure transition at the ACI when the cooling rate in the atomistic simulations is reduced to an experimentally-comparable level; (b) the number of atoms participating in the STZs exponentially increases with the number of dislocations arriving at the ACI at an early stage of the dislocation-ACI reaction, but is linearly proportional to the number of absorbed dislocations at a later stage; (c) the dislocation absorption-induced instability in metallic glasses occurs through a three-stage process, i.e., the activation of STZs in the region between icosahedral (ICO) clusters, the coalescence of newly formed STZs, and then the breakdown of ICOs; (d) the model parameters in the continuum-level constitutive relations and kinetic rules are found to be sensitive to cooling rates; and (e) the local stress states ahead of the instability band in glassy phases map surprisingly well with the Mohr-Coulomb criterion regardless of the applied stress at the macroscopic level. The gained knowledge may provide a pathway of connecting the atomistic deformation physics of an A/C-MC with its overall mechanical performance, which is currently difficult to achieve in laboratory experiments. [ABSTRACT FROM AUTHOR]

We developed a plasma activation process using a gas mixture of O 2 /NH 3 /H 2 O for direct bonding, which realized the combination of bulk aluminum oxide (Al 2 O 3) and yttria-stabilized cubic zirconia (YSZ) without interlayers for the first time. The bonding could withstand multiple mechanical grinding and polishing processes and exhibited sufficient bonding strength for device micro/nanofabication. A nanoscale, sharp, and layered crystalline bonding interface with fewer grain boundaries was confirmed by transmission electron microscopy. The interfacial structure is well-suited for superior performance in high dielectric constant metal–oxide–semiconductor field-effect transistors. Moreover, this bonding method is universal for the fabrication of Al 2 O 3 /SiO 2 and YSZ/SiO 2 heterostructures. Fabrication of the Al 2 O 3 /YSZ heterogeneous structure using the O 2 /NH 3 /H 2 O plasma activation, which was also universal for the direct bonding Al 2 O 3 /SiO 2 and YSZ/SiO 2. Image, graphical abstract [ABSTRACT FROM AUTHOR]

High entropy alloys (HEA) are an unusual class of materials where mixtures of elements are stochastically arrayed on a simple crystalline lattice. These systems exhibit remarkable functionality, often along several distinct axes: e.g., the examples [TaNb]1-x(TiZrHf)x are high strength and damage resistant refractory metals that also exhibit superconductivity with large upper critical fields. Here we report the discovery of an f-electron containing HEA, [TaNb]0.31(TiUHf)0.69, which is the first to include an actinide ion. Similar to the Zr-analogue, this material crystallizes in a body-centered cubic lattice with the lattice constant a = 3.41(1) Å and exhibits phonon mediated superconductivity with a transition temperatures Tc ≈ 3.2 K and upper critical fields Hc2 ≈ 6.4 T. These results expand this class of materials to include actinide elements, shows that superconductivity is robust in this sub-group, and opens the path towards leveraging HEAs as functional waste forms for a variety of radioisotopes. [ABSTRACT FROM AUTHOR]

The Ni 11 (HPO 3) 8 (OH) 3 /Mn 3 O 4 (named as NiPi/Mn 3 O 4) composite with crystalline/amorphous interface was prepared by electrochemical activation, which exhibited high activity and well stability toward hydrogen evolution reaction. The design of electrocatalysts with cost-efficient, highly-efficient and stable for hydrogen evolution reaction (HER) is significant to alleviate energy crisis in the future. Herein, we prepared the Ni 11 (HPO 3) 8 (OH) 3 /Mn 3 O 4 (named as NiPi/Mn 3 O 4) composite with crystalline/amorphous interface by electrochemical activation based on Ni 3 P/MnOOH precursor. The precursor was synthesized by two-step method that firstly electrodeposited on nickel foam and then used anodic oxidation under the applied voltage. The XPS analysis manifested that NiPi/Mn 3 O 4 had a strong interface coupling between Ni 11 (HPO 3) 8 (OH) 3 and Mn 3 O 4 contributed to fast kinetics of hydrogen evolution reaction. The morphology of the nanowires and nanoparticles were provided lager contact area between catalyst and electrolyte. Meanwhile, the obvious interface between crystalline and amorphous also resulted in NiPi/Mn 3 O 4 heterostructureted material with faster electron transport and superior stability. Owing to these characteristics, the NiPi/Mn 3 O 4 displays amazing HER activity with low overpotential of 84 mV at 100 mA cm−2 and a long-term stability of over 100 h at 200 mA cm−2 in 1.0 M NaOH solution. The surprising activity of NiPi/Mn 3 O 4 is better than that of most reported catalysts, similar to the state-of-the-art Pt/C. [ABSTRACT FROM AUTHOR]

Three-dimensional crossbar technology has been of great significance for realizing high density and multiple terabytes of data storage in memory devices. However, to further scale down the size of memory devices, a selector exhibiting nonlinear electrical properties should be in series with a memory layer in case of unwanted sneak current disturbance. Conventional selectors usually utilize a complicated multilayer structure to realize the high nonlinearity of current, which might be incompatible with certain manufacturing processes or limit the scalability of memory. Herein, we propose a simple heterojunction diode using an n-type oxide semiconductor, specifically, InGaZnO4 (IGZO), and a p-type phase change material (PCM), specifically, N-doped Cr2Ge2Te6 (NCrGT), to realize self-selective performance. The electrode/IGZO/NCrGT/plug-electrode structure with an IGZO/NCrGT pn diode and NCrGT/plug-electrode Schottky diode can realize bidirectional, self-selective phase change random access memory (PCRAM) for either amorphous or crystalline NCrGT. The approximate equilibrium energy band diagrams for the IGZO/NCrGT pn junction and the IGZO/NCrGT/W hybrid junction were proposed to explain the possible conduction mechanism. We demonstrated that hybrid diode-type PCM memory exhibits both selectivity and resistive switching characteristics. The present findings offer new insight into selector technology for PCM. [ABSTRACT FROM AUTHOR]

Triggered by experimental observations of nanometer-sized Ni precipitate motion in a La2O3 matrix, the migration and morphological evolution by interface diffusion of an initially circular two-dimensional precipitate located near the free surface of its matrix is numerically investigated by means of phase-field simulations. Considering isotropic interface and elastic energies, it is found that the precipitate migrates towards the free surface, suitably adapting its shape during the motion. The case of two precipitates located near the free surface is also considered as well as the problem of an evolving precipitate near a squared corner of the matrix free surfaces. [ABSTRACT FROM AUTHOR]

Heterojunction device performance has strong dependence on its junction interface. ZnO deposition over GaN to achieve a heterojunction is challenging as it usually requires high temperature and vacuum processing. It is even more demanding to achieve a crystalline interface while making ZnO nanorod based heterojunction. Here we report simple solution process for epitaxial growth of ZnO nanorods over GaN. High resolution x-ray diffraction studies revealed highly crystalline c-axis oriented ZnO nanorod growth by a simple hydrothermal process. ZnO/GaN heterojunction device fabricated using hydrothermally synthesized ZnO nanorods showed superior performance compared to polycrystalline sputter deposited ZnO based heterojunction. [ABSTRACT FROM AUTHOR]

Abstract WB 2 /CrN multilayer films with thick modulation periods over 50 nm (Λ = 1400, 315, 235, 150, 55 nm) were synthesized by direct-current magnetron sputtering, and the influence of modulation period on microstructure and mechanical properties for the multilayer films was systematically studied. In WB 2 /CrN multilayer films, CrN sublayers present the columnar microstructure. As Λ decreases, the structure of WB 2 sublayers evolves from (110) orientation to (001) orientation to amorphous structure, and critical crystalline thickness for WB 2 sublayers is over 150 nm here. A transition layer, which shows the columnar crystal with size of 10–11 nm high and 2.5–3.5 nm wide caused by the effect of the crystalline interface of the CrN sublayers, is detected in WB 2 sublayers. Additionally, a-BN, WB 2 , WB 2 (N), CrN, Cr 2 N and Cr 2 O 3 phase are formed in the multilayer films. Moreover, film hardness mainly obeys the rule of mixture. The maximum hardness of 31.2 GPa is obtained at Λ = 315 nm due to crystalline WB 2 sublayers with (001) preferred orientation, and amorphous WB 2 sublayers greatly reduce the film hardness to only 22.3–24.3 GPa at Λ ≤ 235 nm. Consequently, the poor hardness leads to the higher wear rates (5.7–7.8 × 10−7 mm3/mN) of multilayer films with Λ ≤ 235 nm compared with those (2.9–3.3 × 10−7 mm3/mN) of other films. However, both the fracture toughness and adhesive strength of the films present an increasing trend with decreasing Λ, resulting from the soft CrN and BN phases and a certain amount of interface. In conclusion, decreasing the critical crystal-thickness of the WB 2 sublayers, controlling the N content in WB 2 sublayers and getting sharp interfaces will play important roles in developing the higher-performance WB 2 /CrN multilayer films. Highlights • WB 2 /CrN multilayer films with different bilayer periods over 50 nm are prepared. • A transition layer with nano-columnar crystal exists between WB 2 and CrN sublayers. • Critical crystalline thickness of WB 2 sublayers is over 150 nm in this work. • Decreasing bilayer period to ≤235 nm causes a reduction in hardness and wear rate. • Multilayer architecture promotes the film toughness and adhesive strength. [ABSTRACT FROM AUTHOR]

Abstract Bismuth magnesium niobate (Bi 3/2 MgNb 3/2 O 7 , BMN) thin films were prepared on bare SiO 2 /HR-Si and Pt/TiO 2 /SiO 2 /HR-Si substrates by using sol-gel spin coating technique followed by rapid thermal annealing process. The influence of the interface on crystalline structure and tunable dielectric properties of the two types of BMN films were investigated. It was found that the BMN films prepared on SiO 2 /Si substrate with a BMN/SiO 2 interface structure had higher orientation and better crystallinity. The deposited BMN thin films with a BMN/SiO 2 interface structure exhibited superior tunability of 52.5%, while it showed a relative small tunability value of the film with BMN/Pt interface structure. It suggests that the interface state between the films and substrates, electric field distribution, and orientation degree are responsible for the impacts on the microstructure and tunable dielectric properties of the BMN thin films. [ABSTRACT FROM AUTHOR]

This perspective is focused on surfaces and interfaces of crystalline ice studied with sum frequency generation (SFG) spectroscopy by several research groups within these twenty years. The intrinsic interface selectivity of SFG has already enabled one to determine structural aspects of the ice surfaces and interfaces through vibrational signatures of the OH stretch. Here we describe why SFG is suitable for ice surface science and how SFG has revealed the structure and dynamics of dangling bonds, quasi-liquid layer, hydrogen-bond network, and ordered protons at the ice surfaces, ice/substrate interfaces, and ice films on metal surfaces. In particular, we compare SFG spectra of ice reported by different groups to examine consistency between their experiments. We elaborate current controversies on a few SFG studies of ice before presenting future outlook for ice surface science by SFG. Additionally in the appendix we briefly explain some technical issues that may help us resolve conflicts and make progress in the right way. [ABSTRACT FROM AUTHOR]