Thickness Of Interfacial Layer Research Articles

Toughening Immiscible Polymer Blends: The Role of Interface-Crystallization-Induced Compatibilization Explored Through Nanoscale Visualization.

This study explores the novel approach of interface-crystallization-induced compatibilization (ICIC) via stereocomplexation as a promising method to improve the interfacial strength in thermodynamically immiscible polymers. Herein, two distinct reactive interfacial compatibilizers, poly(styrene-co-glycidyl methacrylate)-graft-poly(l-lactic acid) (SAL) and poly(styrene-co-glycidyl methacrylate)-graft-poly(d-lactic acid) (SAD) are synthesized via reactive melt blending in an integrated grafting and blending process. This approach is demonstrated to enhance the interfacial strength of immiscible polyvinylidene fluoride/poly l-lactic acid (PVDF/PLLA) 50/50 blends via ICIC. IR nanoimaging indicates a cocontinuous morphology in the blends. The blend compatibilized with SAD exhibits a higher storage modulus, as unveiled by small amplitude oscillatory shear (SAOS) in the melt state at a temperature below the melting temperature of the stereocomplex (SC) crystals and by DMTA measurements in the solid state. This increase is attributed to the formation of a 200-300 nm thick rigid interfacial SC crystalline layer that is directly visible using AFM imaging and chemically characterized via IR nanospectroscopy. This ICIC also results in a significant toughening of the blend, with the elongation at break increasing more than 20-fold. Moreover, the fracture toughness factor obtained from single edge-notch bending (SENB) tests is doubled with ICIC as compared to the uncompatibilized blend, indicating the strong crack-resistance capability as a result of ICIC. This improvement is also evident in SEM images, where thinner and longer fibrillation is observed on the fractured surface in the presence of ICIC.

Competitive correlation between the interface layers determines the shear strength in Kovar/AgCuTi/Si3N4 joints

AbstractAs a promising high‐thermal‐conductivity ceramics, the direct bonding of Si3N4 with metals remains challenging. Here, we employed active metal brazing of Si3N4 ceramics and Kovar alloys using AgCuTi metal filler, and found that the shear strength in the prepared Kovar/AgCuTi/Si3N4 joints depends on the competitive correlation between the interface layers. The competitive consumption for active element Ti by Kovar/AgCuTi interfacial reactions reduced AgCuTi/Si3N4 interface layer thickness and deteriorated final shear strength, even when using a high‐Ti‐content filler. Surface analysis indicated that interfacial fracture between Ag‐based solid solution and Ti5Si3 was the primary cause of failure. Density functional theory (DFT) revealed that Ag (111)/Fe2Ti (001) interface had higher ideal work of adhesion (Wad) than Ag (111)/Ti5Si3 (001) interface, confirming the importance of AgCuTi/Si3N4 interface layer. Ultimately, by adjusting interface reaction layer thickness, the joints reached a high shear strength of 154.3 MPa.

A comparative analysis on the dynamics of solid-liquid interfacial layer and nanoparticle diameter of magnetohydrodynamic nanofluid flow containing spherical and cylindrical-shaped alumina nanoparticles over a stretching curved surface

In this work, a comparative analysis on magnetohydrodynamic nanofluid flow containing spherical and cylindrical-shaped alumina nanoparticles over a stretching curved surface is mainly focused. The effects of Brownian motion, Joule heating, thermophoresis, chemical reaction and activation energy are taken into consideration in this work. It is important to mention that this analysis considers a 4 % volume fraction of the alumina nanoparticles. A thermal convective and zero-mass flux conditions are imposed to scrutinize the heat transfer analysis. The leading equations are transformed into dimensionless form by using suitable similarity variables. A numerical solution is obtained using the shooting technique. The acquired outcomes depict that greater magnetic factor enhances the skin friction coefficient. The greater magnetic factor, thermal Biot number, Eckert number, and interfacial layer thickness augment the heat transfer rate, while a greater nanoparticle diameter diminishes the thermal transfer rate. A higher magnetic factor has an increasing impact on thermal distribution and a reducing impact on velocity distribution. A greater curvature factor enhances both the velocity and thermal distributions. The concentration distribution is enhanced by the higher interfacial layer thickness and activation energy factor, while it is reduced by a higher nanoparticle diameter, Brownian motion factor, and chemical reaction factor. From the comparative analysis, it is found that the velocity, thermal, and concentration distributions are higher for the cylindrical-shaped nanoparticles compared to spherical-shaped nanoparticles.

Crack patterns in masonry structures using phase field method

This work aims to study the crack pattern in masonry-like structures by a simplified description of the mediumusing a variational damage model. In literature, when modeling fractures in masonry structures, capturingboth fracture types, cracks in units, and cracks at the interface simultaneously, usually requires a complicated scheme. The phase-field method has been widely used recently because of its robustness in capturing variousfracture types. In this work, we consider the mortar and the interface (between the mortar and units) as a thickinterface layer with pseudo-material properties. We conduct numerical tests on a bending beam and a tensilewall using strategies of material properties with a phase field model. As it is not distinguished the crack in themortar and the brick-mortar interface, it is shown in this work that both types of fracture, in the thick interfacelayer and the unit, can be captured just using the phase field method and the simplified micro model.

Relationship between vertical variation of cloud microphysical properties and thickness of the entrainment interfacial layer in Physics of Stratocumulus Top stratocumulus clouds

AbstractThis study examines the vertical variations of cloud microphysics and their correlation with the thickness of the entrainment interfacial layer (EIL) in stratocumulus clouds, observed in the Physics of Stratocumulus Top (POST) aircraft measurement campaign. From the mixing fraction analysis, we identified EIL between the free atmosphere and cloud top for all 15 POST flights, and found that EIL thickness significantly influenced the vertical variation of cloud microphysics and thermodynamics. In several flights, a trend toward stronger homogeneous mixing traits with increasing depth from the cloud top was found, indicative of the vertical movement of mixed (i.e., entrainment‐affected and diluted) parcels. However, in one flight, this trend was limited to the middle part of the cloud only, with the correlation between virtual potential temperature and liquid water content being strongly negative near the cloud top, suggesting limited downward movement of mixed parcels. Another important finding is that there was a robust negative correlation between long‐wave cooling rate near the cloud top and EIL thickness, highlighting differences in radiative cooling rates between mixed and unmixed parcels due to differences in liquid water content between them. These insightful findings will be crucial for enhancing our understanding of the role of EIL in modulating entrainment and the vertical movement of mixed parcels in stratocumulus clouds.

Interfacial layer suppression in ZrO2/TiN stack structured capacitors via atomic layer deposition

Controlling the formation of interfacial layers in dynamic random-access memory (DRAM) capacitors is crucial because it affects electrical performance, such as increasing the equivalent oxide thickness. This study investigates the formation of an interfacial layer during atomic layer deposition (ALD) of ZrO2 on TiN electrodes and examines its influence on electrical properties. Utilizing O3 and H2O as oxygen sources, we quantitatively identified notable differences in the formation of the interfacial TiOx layer. Using O3 results in a thicker TiOx layer with fewer impurities, which lowers the leakage current, whereas H2O creates a thinner interfacial layer with higher impurity levels, leading to an increased leakage current. To optimize these effects, we developed a two-step ALD process that combines both oxygen sources, reducing the interfacial layer thickness while maintaining low leakage currents. This approach significantly improved the electrical performance of capacitors. Furthermore, similar results were observed for HfO2/TiN systems, suggesting that our findings are broadly applicable to high-k dielectric materials.

A comparative study on the electrical properties of Ba0.6Sr0.4TiO3 film capacitors with different top electrodes

Au/Ba0.6Sr0.4TiO3 (BST)/La0.5Sr0.5CoO3 (LSCO) and Pt/BST/LSCO ferroelectric capacitors were successfully constructed on (001) LaAlO3 substrates via off-axis magnetron sputtering. X-ray diffraction (XRD) and Phi scan patterns confirmed that the BST film was epitaxial with an out-of-plane tetragonal phase. The ferroelectric and dielectric measurements reveal that, compared with the Pt/BST/LSCO capacitor, the Au/BST/LSCO capacitor exhibits a larger coercive field (∼139.7 kV/cm), smaller permanent polarization (∼2.94 μC/cm2), and lower tunability (∼65.22 %), which may be attributed to the higher difference in work function and weaker depolarization field screen effect of the top electrode, as well as smaller interfacial capacitance of the Au/BST interface than those of the Pt/BST interface. Therefore, based on series capacitor model and leakage behavior analysis, the thickness and dielectric constant of interfacial layer are quantitatively determined to be 3.52 nm and 12.13 for Pt/BST, and 4.42 nm and 5.82 for Au/BST, respectively. Our results pave a way for improving the dielectric performance in electrically tunable microwave devices.

Emulsification capacity of pectin extracts from persimmon waste: Effect of structural characteristics and pectin-polyphenol interactions

Polyphenol-rich pectin extracts obtained from persimmon waste might have great potential due to their emulsification capacity. Their emulsion stabilizing properties may be influenced by pectin molecular structure and pectin-polyphenol interactions which in turn can be determined by the extraction conditions. Hence, this work aimed to study the influence of the molecular structure characteristics and their respective pectin-polyphenol interactions of three polyphenol-rich persimmon pectin extracts obtained by three different extraction conditions. Low, medium and high severity extraction conditions resulted in covalent phenolics-extract (CP-E), non-covalent phenolics-extract (NCP-E) and free phenolics-extract (FP-E), respectively. The electrical charge of pectin was strongly dependent on the pH, becoming more negative at increasing pH due to carboxyl group dissociation. CP-E and NCP-E in solution had more expanded conformations than FP-E, with greater intermolecular distances and hydrodynamic diameters ranging from 1089 to 1791 nm for CP-E and NCP-E, whereas from 529 to 782 nm for FP-E. Their interfacial layer thickness was thicker at pH 3 than at pH 7, probably due to multilayer organization as a result of less repulsion between pectin chains. All pectin extracts were able to decrease the interfacial tension of an oil droplet from 35 to at least 25 mN/m, with FP-E at pH 3 being the most efficient (13.89 ± 1.07 mN/m). Even so, submicron O/W emulsions with negative ζ-potential values could be formed with all pectin extracts. However, CP-E rendered O/W emulsions with higher colloidal stability than FP-E or NCP-E, which showed aggregation and creaming. These findings provide novel insights to re-valorize pectin from persimmon waste.

The effect of Cu-doping to the DLC interlayer on the temperature dependent current-conduction mechanisms and barrier shape of the Schottky devices

The objective of this study is to determine the temperature and voltage-dependent current conduction mechanisms (CCMs) of the Al/Cu-doped DLC/p-Si Schottky device. It is aimed to obtain extensive and detailed data by current-voltage (I–V) measurements taken with 0.3 V voltage steps in the ±4 V voltage range, at 30 K intervals from 80 K to 410 K. Firstly, an examination of the semi-logarithmic I–V curve revealed that the low temperature (LTs, 80 K–170 K), medium temperature (MTs, 200 K–290 K) and high temperature (HTs, 320 K–410 K) regions should be examined separately. The basic parameters of the Schottky device such as the ideality factor (n), reverse saturation current (Io) and zero-biasing potential barrier height (ΦBo) were obtained separately for LTs, MTs and HTs by the Thermionic Emission (TE) theory. The results obtained show that the device deviates from ideality, especially in LTs and HTs, and the n values decrease with increasing temperature, while the ΦBo values increase. The analysis of the presence of other CTMs in the Schottky device revealed that Field Emission (FE) and Thermionic Field Emission (TFE) were effective in LTs and MTs, while FE was effective in HTs. Since it is thought that quantum mechanical CTMs cannot be the cause of such a deviation from ideality due to the interface layer thickness, the existence of Gaussian Distribution originating from lateral barrier inhomogeneity was investigated. As a result, it is concluded that the Multiple Gaussian Distribution (MGD) is dominant in the possible CTMs of the Schottky device.

Effects of Ni addition on wettability and interfacial microstructure of Sn-0.7Cu-xNi solder alloy

Purpose This paper aims to study the effect of different Ni content on the microstructure and properties of Sn-0.7Cu alloy. Then, the spreading area, wetting angle, interface layer thickness and microstructure of the soldering interface was observed and analyzed at different soldering temperatures and times. Design/methodology/approach Sn-0.7Cu-xNi solder alloy was prepared by a high-frequency induction melting furnace. Then Sn-0.7Cu-xNi alloy was soldered on a Cu substrate at different soldering temperatures and times. Findings It was found that Ni made the intermetallic compounds in the Sn-0.7Cu solder alloy gradually aggregate and coarsen, and the microstructure was refined. The phase compositions of the solder alloy are mainly composed of the ß-Sn phase and a few intermetallic compounds, Cu6Sn5 + (Cu, Ni)6Sn5. The maximum value of 12.1 HV is reached when the Ni content is 0.1 Wt.%. When the Ni content is 0.5 Wt.%, the wettability of the solder alloy increases by about 15%, the interface thickness increases by about 8.9% and the scallop-like structure is the most refined. When the soldering time is 10 min and the soldering temperature is 280 °C, the wettability of Sn-0.7Cu-0.2Ni is the best. Originality/value It is groundbreaking to combine the change in soldering interface with the soldering industry. The effects of different soldering temperatures and times on the Sn-0.7Cu-xNi alloy were studied. Under the same conditions, Sn-0.7Cu-0.2Ni exhibits better wettability and more stable solder joint stability.

Interfacial engineering of Pickering emulsions stabilized by pea protein-alginate microgels for encapsulation of hydrophobic bioactives

This study aims to investigate the effects of interfacial layer composition and structure on the formation, physicochemical properties and stability of Pickering emulsions. Interfacial layers were formed using pea protein isolate (PPI), PPI microgel particles (PPIMP), a mixture of PPIMP and sodium alginate (PPIMP-SA), or PPIMP-SA conjugate. The encapsulation and protective effects on different hydrophobic bioactives were then evaluated within these Pickering emulsions. The results demonstrated that the PPIMP-SA conjugate formed thick and robust interfacial layers around the oil droplet surfaces, which increased the resistance of the emulsion to coalescence, creaming, and environmental stresses, including heating, light exposure, and freezing-thawing cycle. Additionally, the emulsion stabilized by the PPIMP-SA conjugate significantly improved the photothermal stability of hydrophobic bioactives, retaining a higher percentage of their original content compared to those in non-encapsulated forms. Overall, the novel protein microgels and the conjugate developed in this study have great potential for improving the physicochemical stability of emulsified foods.

Investigation and evaluation of high-temperature lead-bismuth eutectic (LBE) corrosion resistance and compression performance of the FeCrAl-based coatings

The high-temperature lead-bismuth eutectic (LBE) corrosion resistance and ring compression performance of the Fe15Cr11Al2Si, Fe15Cr11Al0.5Y, and Fe15Cr11Al2Si0.5Y coatings were investigated. Even if the corrosion test temperature reaches 800 °C, all these coatings can effectively protect the steel cladding tube. After the corrosion test temperature exceeded 660 °C, an obvious Al-rich oxide layer was formed on the surface of the coating, and Al element enrichment occurred at the interface between the coating and the substrate. After the corrosion test at 800 °C, holes appeared in the thick interface layer of the Fe15Cr11Al2Si0.5Y coating. The Fe15Cr11Al2Si coating cracked after the ring compression test with a deformation rate of 3%, and the coating peeled off after the deformation rate reached 5%. When the deformation rate reached 5%, there was still no cracking in the Fe15Cr11Al0.5Y coating. When the deformation rate reached 30%, the coating cracked, but the cracked coating was still tightly bonded with the substrate. The Fe15Cr11Al2Si0.5Y coating has the worst compression performance, even if the deformation rate is 1%, the coating still peels off obviously. The underlying mechanism for the evolution of corrosion resistance and compression performance was discussed.

Mechanism of sodium lauryl sulfate reducing froth stability of dodecylamine in hematite flotation: Experiments and molecular dynamics simulation

In this study, the influence of sodium lauryl sulfate (SLS) on the stability of dodecylamine (DDA) froth during the reverse flotation of hematite was investigated due to the frequent issue of excessively viscous foam leading to suboptimal reverse flotation outcomes. The research involved conducting flotation tests and two/three-phase froth stability assessments to explore how a specific molar ratio combination of DDA and SLS could enhance the flotation performance while simultaneously mitigating froth stability. The investigation into the mechanism by which SLS reduces the stability of DDA froth was aided by molecular dynamics simulations. The findings revealed that in the collector system comprising DDA and SLS, several key changes occurred at the molecular level. These included a decrease in the thickness of the electric double layer at the interface, a reduction in the thickness of the gas–liquid interface layer, weakening of the interaction strength between the head group and water molecules, a decrease in the coordination numbers of water molecules in the first hydration layer, and an enhanced migration ability of water molecules. Furthermore, there was an increased inclination angle between the head groups or molecular chains of the collector and the Z-axis, resulting in a diminished interaction depth between the head group and water and a closer positioning of the molecular tail chain to the gas–liquid interface with a more pronounced curvature. Consequently, these molecular adjustments led to a sparser arrangement of DDA molecules at the gas–liquid interface, lower coverage of the interface adsorption layer, and increased gas permeation, ultimately reducing DDA froth stability. The aforementioned conclusions provide a comprehensive molecular-level analysis of the principal mechanisms that can effectively reduce foam stability, including the attenuation of molecular head group-water interactions, reduction in gas–liquid interface layer thickness, decrease in gas–liquid interface orderliness, and enhancement of water molecule migration capability. The implications of this research extend to providing theoretical insights for addressing foam control challenges in DDA flotation processes.

Sustained-release mechanism of β-Cyclodextrin/cationic cellulose-stabilized Pickering emulsions loaded with citrus essential oil

Citrus oil (CO) is a commonly used natural flavor with high volatility, which is not conducive to sustained release under food environmental stress. This study constructed novel β-cyclodextrin/cationic cellulose nanocrystal (β-CD/C-CNC) complexes via noncovalent interaction, which were used to stabilize CO-loaded Pickering emulsions (PEβ-CD/C-CNC). The C-CNC greatly improved the physical stability, droplet dispersion and viscoelasticity of PEβ-CD/C-CNC by forming a tight network structure, as verified by rheological behavior. Moreover, C-CNC improved the wettability of β-CD/C-CNC complexes and enhanced the interaction between adjacent β-CD/C-CNC complexes. C-CNC also contributed to the interfacial viscoelasticity, hydrated mass, and layer thickness via the interfacial dilational modulus and QCM-D. β-CD/C-CNC complexes adsorbed on the oil–water interface gave rise to a dense filling layer as a physical barrier, enhancing the sustained-release performance of PEβ-CD/C-CNC by limiting diffusion of citrus essential oil into the headspace. This study provides new technical approaches for aroma retention in the food industry.

Effect of non-covalent binding of tannins to sodium caseinate on the stability of high-internal-phase fish oil emulsions

In this study, we designed the noncovalent binding of sodium caseinate (SC) to tannic acid (TA) to stabilize high internal phase emulsions (HIPEs) used as fish oil delivery systems. Hydrogen bonding was the dominant binding force, followed by weak hydrophobic interaction and weak van der Waals forces, as demonstrated by FTIR, fluorescence spectroscopy, and molecular docking experiments, with a binding constant of 3.25 × 106, a binding site of 1.2, and a static quenching of the binding. Increasing SC:TA from SC to 2:1 decreased the particle size from 107.37 ± 10.66 to 76.07 ± 2.77 nm and the zeta potential from −6.99 ± 2.71 to −22 ± 2.42 mV. TA increased the interfacial tension of SC, decreased the surface hydrophobicity from 1.3 × 104 to 1.6 × 103 and improved the oxidation resistance of SC. The particle size of high internal phase emulsions stabilized by complexes with different mass ratios (SC:TA from 1:0 to 2:1) increased from 4.9 ± 0.02 to 12.9 μm, the potential increased from −32.37 ± 2.7 to −35.07 ± 2.58 mV, and the instability index decreased from 0.75 to 0.02. Thicker interfacial layers could be observed by laser confocal microscopy, and an increase in the storage modulus indicated a formation of a stronger gel network. SC:TA of 1:0 showed emulsion breakage after 14 d of storage at room temperature. SC:TA of 2:1 showed the lowest degree of oil-water separation after freeze-thaw treatment. Especially, the most stable high endo-phase emulsion (at SC:TA of 2:1) prepared at each mass ratio was selected for further stability exploration. The emulsion particle size increased only from 15.63 ± 0.06 to 22.27 ± 0.35 μm at salt ion concentrations of 50–200 mM and to 249.33 ± 31.79 μm at 300 mM. The instability index and storage modulus of the high endo-phase emulsions increased gradually with increasing salt ion concentrations. At different heating temperatures (55–85 °C), the instability index of the high internal phase emulsion gradually decreased and the storage modulus gradually increased. Meanwhile, at 50 °C for 15 d of accelerated oxidation, the content of hydroperoxide decreased from 53.32 ± 0.18 to 37.48 ± 0.77 nmol/g, about 29.7 %, and the thiobarbituric acid value decreased from 1.06 × 103 to 0.8 × 103, about 24.5 %, in the high endo-phase emulsions prepared by 2:1 SC:TA compared to the fish oils, and the SC-stabilized high endo-phase only emulsion broke at the sixth day of oxidation. From the above findings, it was concluded that the high internal phase emulsion prepared with SC:TA of 2:1 can be used as a good delivery system for fish oil.

Preparation of protein-polyphenol-polysaccharide ternary complexes to regulate the interfacial structure of emulsions: Interfacial behavior and emulsion stability

This study investigated the effect of protein-polyphenol-polysaccharide ternary complexes prepared from polysaccharides with different charges on emulsion stability. Sodium alginate (ALG), chitosan hydrochloride (CHC) and oat β-glucan (OG) were used as representational polysaccharides. The interfacial rheology showed that CHC increased the adsorption rate of WPI-rutin complexes at the oil-water interface, while ALG and OG reduced the adsorption rate. Furthermore, WPI-Rutin-CHC complexes effectively reduced the interfacial tension from 11.16 mN/m to 9.41 mN/m. Compared with other ternary complexes, the oil-water interface layer composed of WPI-Rutin-CHC complexes had the highest interfacial viscoelasticity and mechanical strength. Moreover, the emulsion prepared by WPI-Rutin-CHC complexes had the lowest instability index (0.17) and the smallest droplet size (660 nm), indicating the highest stability among all the emulsions. The microstructure results indicated that the thick interfacial layer was observed in WPI-Rutin-CHC emulsion, while thin interfacial layers were found in other emulsions. These results revealed the stability mechanism of emulsions prepared by ternary complexes and provided guidance for the preparation of stable emulsions.

From Nanoscale to Macroscale Characterization of Sulfur-Modified Oxidized Carbon Nanotubes in Styrene Butadiene Rubber Compounds.

The homogeneous dispersion of carbon nanotubes (CNTs) in a rubber matrix is a key factor limiting their amazing potential. CNTs tend to agglomerate into bundles due to van der Waals interactions. To overcome this limitation, CNTs have been surface-modified with oxygen-bearing groups and sulfur. Using atomic force microscopy (AFM) techniques, a deep nanoscale characterization of the morphology, the degree of dispersion of the CNTs in the styrene butadiene rubber (SBR) matrix, and the thickness of the interfacial layer was carried out in this study. In this context, the results from nanoscale characterization showed that the thermal oxidation-sulfur treatment leads to a composite with better dispersion in the matrix, as well as a thicker interfacial layer, indicating a stronger filler-rubber interaction. The second part of this work focused on the macroscale results, such as the Payne effect, vulcanization curves, and mechanical properties. The Payne effect, vulcanization curves, and mechanical properties confirmed the lower reinforcing effect observed in the case of the chemical oxidation treatment because, on the one hand, this composite showed the highest agglomeration of CNTs after the acid treatment. On the other hand, the presence of acid residues provoked the absorption of basic accelerators on the surface of the CNTs.

Antimony-Platinum Modulated Contact Enabling Majority Carrier Polarity Selection on a Monolayer Tungsten Diselenide Channel.

We develop a novel metal contact approach using an antimony (Sb)-platinum (Pt) bilayer to mitigate Fermi-level pinning in 2D transition metal dichalcogenide channels. This strategy allows for control over the transport polarity in monolayer WSe2 devices. By adjustment of the Sb interfacial layer thickness from 10 to 30 nm, the effective work function of the contact/WSe2 interface can be tuned from 4.42 eV (p-type) to 4.19 eV (n-type), enabling selectable n-/p-FET operation in enhancement mode. The shift in effective work function is linked to Sb-Se bond formation and an emerging n-doping effect. This work demonstrates high-performance n- and p-FETs with a single WSe2 channel through Sb-Pt contact modulation. After oxide encapsulation, the maximum current density at |VD| = 1 V reaches 170 μA/μm for p-FET and 165 μA/μm for n-FET. This approach shows promise for cost-effective CMOS transistor applications using a single channel material and metal contact scheme.

Effects of drawing speed on microstructure and properties of Cu-Ni-Si alloy clad AA8030 alloy composites prepared by continuous casting composite technology

The Cu-Ni-Si alloy clad AA8030 alloy rod was prepared by continuous casting composite technology with gradient-varying drawing speeds, and the influences of drawing speed on the casting quality and microstructure of Cu-Ni-Si alloy clad AA8030 alloy rod were systematically studied. The drawing speed at which satisfactory continuous casting quality could be obtained was 90–120 mm/min. Meanwhile, axial columnar grains favorable for subsequent plastic processing were obtained, although the angle between columnar grains and axial direction increased with the increases of drawing speed. Moreover, with the drawing speed increasing from 90 mm/min to 120 mm/min, the thickness of composite interfacial layers was significantly increased, and the morphology of interfacial phases was gradually changed. The Cu-Ni-Si alloy cladding layer was cut from the composite to perform solution and aging experiments. The results showed that the solid solution effect of the as-cast Cu-Ni-Si alloy was consistent with that of the solution-treated Cu-Ni-Si alloy because of the rapid cooling characteristics of continuous casting composite technology, which solved the problem that the composite rod could not be solution treated as a whole due to the lower melting point of the Al core.

Resistive switching suppression in metal/Nb:SrTiO3 Schottky contacts prepared by room-temperature pulsed laser deposition

Deepening the understanding of interface-type resistive switching (RS) in metal/oxide heterojunctions is a key step for the development of high-performance memristors and Schottky rectifiers. In this study, we address the role of metallization technique by fabricating prototypical metal/Nb-doped SrTiO3 (M/NSTO) Schottky contacts via pulsed laser deposition (PLD). Ultrathin Pt and Au electrodes are deposited by PLD onto single-crystal (001)-terminated NSTO substrates and interfacial transport is characterized by conventional macroscale methods and nanoscale Ballistic Electron Emission Microscopy. We show that PLD metallization gives Schottky contacts with highly reversible current-voltage characteristics under cyclic polarization. Room-temperature (RT) transport is governed by thermionic emission with Schottky barrier height ϕB(Pt/NSTO)∼0.71−0.75eV , ϕB(Au/NSTO)∼0.70−0.83eV and ideality factors as small as n(Pt/NSTO)∼1.1 and n(Au/NSTO)∼1.6 . RS remains almost completely suppressed upon imposing broad variations of the Nb doping and of the external stimuli (polarization bias, working temperature, ambient air exposure). At the nanoscale, we find that both systems display high spatial homogeneity of ϕB ( ⩽50meV ), which is only partially affected by the NSTO mixed termination ( |ϕB(M/SrO)−ϕB(M/TiO2)|<35meV ). Experimental evidences and theoretical arguments—based on a metal-insulator-semiconductor description of the M/NSTO—indicate that the PLD metallization mitigates interfacial layer effects responsible for RS. This occurs thanks to the reduction of the interfacial layer thickness and to the creation of an effective barrier against the permeation of ambient gas species affecting charge trapping and redox reactions. This description allows to rationalize interfacial aging effects, observed upon several-months-exposure to ambient air, in terms of a slow interfacial re-oxidation. Our work contributes to the fundamental understanding of interface-type RS and demonstrates that RT PLD offers a viable platform for the realization of robust, RS-free NSTO-based Schottky contacts.