Plasmonic Field Enhancement for Vibration Spectroscopy at Metal/Water Interfaces

Electrochemical （EC） reactions play vital roles in many disciplines, and its molecular-level understanding is highly desired, in particular under reactions. The vibration spectroscopy is a powerful in situ technique for chemical analysis, yet its application to EC reactions is hindered by the strong attenuation of infrared （IR） light in both electrodes and electrolytes. Here we demonstrate that by incorporating appropriate sub-wavelength plasmonic structures at the metal electrode, the IR field at the EC interface can be greatly enhanced via the excitation of surface plasmon. This scheme facilitates in situ vibrational spectroscopic studies, especially using the surface-specific sum-frequency generation technique.

Investigation of Interfaces in Remelted A356-SiC Particulate Duralcan Metal Matrix Composite

For the manufacture of Al-based metalmatrix composites, the foundry productionroute can provide less expensive products witha greater flexibility in meeting designer’s needsamong a vaviety of fablication routes. Recent-ly, a commercially produced foundry ingot,the Duralcan composite of A356 Al alloy +20

Effect of chromium interlayer thickness on interfacial thermal conductance across copper/diamond interface

The thermal conductivity of diamond particles reinforced copper matrix composite as an attractive thermal management material is significantly lowered by the non-wetting heterointerface.The paper investigates the heat transport behavior between a 200-nm Cu layer and a single-crystalline diamond substrate inserted by a chromium(Cr)interlayer having a series of thicknesses from 150 nm down to 5 nm.The purpose is to detect the impact of the modifying interlayer thickness on the interfacial thermal conductance(h)between Cu and diamond.The time-domain thermoreflectance measurements suggest that the introduction of Cr interlayer dramatically improves the h between Cu and diamond owing to the enhanced interfacial adhesion and bridged dissimilar phonon states between Cu and diamond.The h value exhibits a decreasing trend as the Cr interlayer becomes thicker because of the increase in thermal resistance of Cr interlayer.The high h values are observed for the Cr interlayer thicknesses below 21 nm since phononic transport channel dominates the thermal conduction in the ultrathin Cr layer.The findings provide a way to tune the thermal conduction across the metal/nonmetal heterogeneous interface,which plays a pivotal role in designing materials and devices for thermal management applications.

Metal–ligand interfaces for well-defined gold nanoclusters

Ligand engineering for well-defined gold nanoclusters(Au NCs) is getting more extensive attention. Organizing the Au-ligand interfaces on gold NCs can achieve the structural and functional control. This review focuses on the Au-ligand interfaces including gold-phosphorus(Au-P), gold-sulfur(Au-S), gold-selenium(Au-Se), gold-carbon(Au-C), and gold-nitrogen(Au-N), derived from the bonding between Au atoms and the different ligands(e.g., organic phosphine, thiolate, selenolate, alkynyl,n-heterocyclic carbene and nitrogenous ligands). The formation mechanism of Au-ligand interfaces is well discussed. In addition, the effects of Au-ligand interfaces on the stability, optical property, and catalysis are also presented. We hope the advances in this research area can boost the development of Au NC sciences.

First-Principles Study of the Polar TiC/Ti Interface

The interface structure, work of adhesion, and bonding character of the polar TiC/Ti interface have been examined by the first-principles density functional plane-wave pseudopotential calculations. Both Ti- and C-terminated interfaces including six different interface structures were calculated, which present quite different features. For the Ti-terminated interface, the interfacial Ti-Ti bond has a strong metallic and weak covalent character; while for the C-terminated interface, the interfacial bond is a strong polar covalent interaction between the Ti-3d and C-2p orbital. The work of adhesion of C-terminated interface is nearly 9 J/m2 stronger than that of the Ti-terminated. It is found that each termination has relatively large work of adhesion, which is consistent with other polar interfaces.

A study of metal/die interfacial heat transfer behavior of vacuum die cast pure copper

High pressure die casting copper is used to produce rotors for induction motors to improve efficiency.Experiments were carried out for a special"step-shape"casting with different step thicknesses.Based on the measured temperature inside the die,the interfacial heat transfer coefficient(IHTC)at the metal/die interface during vacuum die casting was evaluated by solving the inverse problem.The IHTC peak value was 4.5×10^3-11×10^3 W·m^-2·K^-1 under the basic operation condition.The influences of casting pressure,fast shot speed,pouring temperature and initial die surface temperature on the IHTC peak values were investigated.Results show that a greater casting pressure and faster shot speed could only increase the IHTC peak values at the location close to the ingate.An increase of pouring temperature and/or initial die surface temperature significantly increases the IHTC peak values.

Effect of the stoichiometry on the electronic structure of the Ni(111)/α-Al_2O_3(0001) interface:a first-principles investigation

In this paper first-principles calculations of Ni（111）/α-Al2O3（0001） interfaces have been performed, and are compared with the preceding results of the Cu （111）/α-Al2O3（0001） interface [2004 Phil. Mag. Left. 84 425]. The AI- terminated and O-terminated interfaces have quite different adhesion mechanisms, which are similar to the Cu（111）/α Al2O3（0001） interface. For the O-terminated interface, the adhesion is caused by the strong O-2p/Ni-3d orbital hybridization and ionic interactions. On the other hand, the adhesion nature of the Al-terminated interface is the image-like electrostatic and Ni-Al hybridization interactions, the latter is substantial and cannot be neglected. Charge transfer occurs from Al2O3 to Ni, which is opposite to that in the O=terminated interface. The charge transfer direction for the Al-terminated and O-terminated Ni（111）/α-A1203（0001） interfaces is similar to that in the corresponding Cu（111）/α- Al2O3（0001） interface, but there exist the larger charge transfer quantity and consequent stronger adhesion nature, respectively.

Microscopic Approach of Adhesion and Wetting of Liquid Metal on Solid Ionocovalent Oxide Surface

The adhesion and wetting of non-reactive liquid metals with solid ionocovalent oxides are studied on the basis of the experimental work of adhesion W data obtained with the sessile drop method.An analysis of the experimental W values of different liquid metals on various solid oxides is first performed to evidence the de- pendence of the work of adhesion of a metal/oxide system on the electron density of the metal and on the thermodynamic stability of the oxide.An electronic model is then proposed to describe the microscopic mech- anism of metal-oxide interactions.Based on the model,the contact angle and the work of adhesion of different liquid metals on various solid oxides can be interpreted and estimated,and their correlations to the various physical quantities of the oxides can be easily deduced.The basic consideration of the model is that the adhe- sion between a metal and an oxide is assured by the electron transfer from the metal into the oxide valence band which is not completely filled of electrons at high temperatures,and is enhanced when this electron trans- fer at the metal/oxide interface is intensified.The influence of interface defects on the wetting and adhesion is suggested and discussed.

Effect of NO annealing on charge traps in oxide insulator and transition layer for 4H-SiC metal–oxide–semiconductor devices

The effect of nitric oxide（NO） annealing on charge traps in the oxide insulator and transition layer in n-type4H–Si C metal–oxide–semiconductor（MOS） devices has been investigated using the time-dependent bias stress（TDBS）,capacitance–voltage（C–V）,and secondary ion mass spectroscopy（SIMS）.It is revealed that two main categories of charge traps,near interface oxide traps（Nniot） and oxide traps（Not）,have different responses to the TDBS and C–V characteristics in NO-annealed and Ar-annealed samples.The Nniotare mainly responsible for the hysteresis occurring in the bidirectional C–V characteristics,which are very close to the semiconductor interface and can readily exchange charges with the inner semiconductor.However,Not is mainly responsible for the TDBS induced C–V shifts.Electrons tunneling into the Not are hardly released quickly when suffering TDBS,resulting in the problem of the threshold voltage stability.Compared with the Ar-annealed sample,Nniotcan be significantly suppressed by the NO annealing,but there is little improvement of Not.SIMS results demonstrate that the Nniotare distributed within the transition layer,which correlated with the existence of the excess silicon.During the NO annealing process,the excess Si atoms incorporate into nitrogen in the transition layer,allowing better relaxation of the interface strain and effectively reducing the width of the transition layer and the density of Nniot.

Electronic Theory of Thermodynamic Adhesion inMetal/Ceramic Systems

The thermodynamic adhesion between a metal and a ceramic crystal was believed to be the result of theelectron transfer from the metal into the cerainic crystal. From an electronic point of view, such an electrontransfer at the metal/ceramic interface may be represented by the tunnelling of the metal conduction electron into the ceramic bandgap. Theoretical analysis of the quantum tunnelling process at an intimate rnetal-semicon-ductor contact were performed . and the relationship between adhesion energies and Schottky barrier heights ofvarious metal/semiconductor or insulator interfaces was dcduced .

Interfacial characteristics and properties of a low-clad-ratio AA4045/AA3003 cladding billet fabricated by semi-continuous casting

A low-clad-ratio AA4045/AA3003 cladding billet was fabricated using a semi-continuous casting process and was subsequently extruded indirectly into a cladding pipe. The temperature distribution near the interface was measured. The microstructures, elemental distribution, Vickers hardness around the bonding interface, and the interfacial shear strength were examined. The results showed that the interface temperature rebounded when AA4045 melt contacted the supporting layer. The two alloys bonded well, with few defects, via the diffusion of Si and Mn in the temperature range from 569℃ to 632℃. The mean shear strength of the bonding interface was 82.3 MPa, which was greater than that of AA3003（75.8 MPa）, indicating that the two alloys bonded with each other metallurgically via elemental interdiffusion. Moreover, no relative slip occurred between the two alloys during the extrusion process.

Brazed joints of CBN grains and AISI 1045 steel with AgCuTi-TiC mixed powder as filler materials

The brazing process of cubic boron nitride （CBN） grains and AISI 1045 steel with AgCuTi-TiC mixed powder as a filler material was carried out.The joining strength and the interfacial microstructure were investigated.The experimental results indicate that the spreading of the molten filler material on AISI 1045 steel is decreased with the increase of TiC content.A good interface is formed between the TiC particulates and AgCuTi alloy through the wetting behavior.In the case of AgCuTi＋16wt% TiC,the strength of the brazed steel-to-steel joints reached the highest value of 95MPa dependent upon the reinforcement effect of TiC particles within the filler layer.Brazing resultants of TiB2,TiB,and TiN are produced at the interface of the CBN grains and the AgCuTi-TiC filler layer by virtue of the interdiffusion of B,N,and Ti atoms.

Interfacial oxidized Pd species dominate catalytic hydrogenation of polar unsaturated bonds

The determination of catalytically active sites is crucial for the design of efficient and stable catalysts toward desired reactions.However,the complexity of supported noble metal catalysts has led to controversy over the locations of catalytically active sites(e.g.,metal,support,and metal/support interface).Here we develop a structurally controllable catalyst system(Pd/SBA-15)to reveal the catalytic active sites for the selective hydrogenation of ketones to alcohol using acetophenone hydrogenation as model reaction.Systematic investigations demonstrated that unsupported Pd nanocrystals have no catalytic activity for acetophenone hydrogenation.However,oxidized Pd species were catalytically highly active for acetophenone hydrogenation.The catalytic activity decreased with the decreased oxidation state of Pd.This work provides insights into the hydrogenation mechanism of ketones but also other unsaturated compounds containing polar bonds,e.g.,nitrobenzene,N-benzylidene-benzylamine,and carbon dioxide.

In-situ tracking of phase conversion reaction induced metal/metal oxides for efficient oxygen evolution

Due to the unique interface and electronic structure,metal/metal oxide composite electrocatalysts have been designed and exploited for electrocatalytic oxygen evolution reaction(OER)in alkaline solution.However,how to fabricate metal/metal oxides with abundant interfaces and well-dispersed metal phases is a challenge,and the synergistic effect between metal and metal oxides on boosting the electrocatalytic activities is still ambiguous.Herein,by controlling the lithium-induced conversion reaction of metal oxides,metal/metal oxide composites with plentiful interfaces and excellent electrical interconnection are fabricated,which can enhance the active sites,and accelerate the mass transfer during the electrocatalytic reaction.As a result,the electrocatalytic oxygen evolution activities of the as-fabricated metal/metal oxide composite catalysts including NiCo/NiCo2O4,NiMn/NiMn2O4 and CoMn/CoMn2O4 are greatly improved.The catalytic mechanism is also explored using the in-situ X-ray and Raman spectroscopic tracking to uncover the real active centers and the synergistic effect between the metal and metal oxides during water oxidation.Density functional theory plus U(DFT+U)calculation confirms the metal in the composite can optimize the catalytic reaction path and reduce the reaction barrier,thus boosting the electrocatalytic kinetics.

Interfacial engineering of printable bottom back metal electrodes for full-solution processed flexible organic solar cells

Printing of metal bottom back electrodes of flexible organic solar cells（FOSCs） at low temperature is of great significance to realize the full-solution fabrication technology. However, this has been difficult to achieve because often the interfacial properties of those printed electrodes, including conductivity, roughness, work function,optical and mechanical flexibility, cannot meet the device requirement at the same time. In this work, we fabricate printed Ag and Cu bottom back cathodes by a low-temperature solution technique named polymer-assisted metal deposition（PAMD） on flexible PET substrates. Branched polyethylenimine（PEI） and ZnO thin films are used as the interface modification layers（IMLs） of these cathodes. Detailed experimental studies on the electrical, mechanical, and morphological properties, and simulation study on the optical properties of these IMLs are carried out to understand and optimize the interface of printed cathodes. We demonstrate that the highest power conversion efficiency over 3.0% can be achieved from a full-solution processed OFSC with the device structure being PAMDAg/PEI/P3 HT：PC61BM/PH1000. This device also acquires remarkable stability upon repeating bending tests.

Oxide Layers on(0001) Plane of Zircaloy-4 After Corrosion at 360 °C in Lithiated Aqueous Solution

The microstructures of the oxide layers formed on near （0001） plane of Zircaloy-4 were investigated by autoclave tests at 360 ℃ in lithiated aqueous solution. Oxygen-rich regions with hcp structure were observed at the undulating O/M interface, and the inner surface morphology of the oxide layers formed on （0001） was only concave- convex. Monoclinic, tetragonal and cubic phases and a kind of zirconium sub-oxide with bcc structure were detected in the oxide layer near the metal matrix. This zirconium sub-oxide layer had a coherent relationship with a-Zr matrix, and the growth direction of the zirconium sub-oxide layer was nearly parallel to the [0001] direction of a-Zr regardless of the orientation of metal matrix. The orientations scattering of columnar grains formed on near （0001） plane differ from that formed on near （1010） plane.

Effect of Heat Input on Microstructure and Mechanical Properties of Joints Made by Bypass-Current MIG Welding–Brazing of Magnesium Alloy to Galvanized Steel

Experiments were carried out with bypass-current MIG welding–brazing of magnesium alloy to galvanized steel to investigate the effect of heat input on the microstructure and mechanical properties of lap joints. Experimental results indicated that the joint efficiency tended to increase at first and then to reduce with the increase of heat input. The joint efficiency reached its maximum of about 70% when the heat input was 155 J/mm. The metallurgical bonding between magnesium alloy and steel was a thin continuous reaction layer, and the intermetallic compound layer consisted of Mg–Zn and slight Fe–Al phases. It is concluded that bypass-current MIG welding–brazing is a stable welding process, which can be used to achieve defect-free joining of magnesium alloy to steel with good weld appearances.

Three-dimensional flexible Au nanoparticles-decorated TiO_(2) nanotube arrays for photoelectrochemical biosensing

Controlling the charge transfer and thus enhancing the excitons’lifetime are the key to the realization of efficient photoelectrochemical(PEC)devices.Moreover,fabrication of flexible and collapsible sensors can greatly facilitate the implementation of smart PEC sensing devices into practical applications.Herein,we sagely designed and successfully fabricated three-dimensional flexible Au nanoparticles-decorated TiO_(2) nanotube arrays(Au@TiO2)for the efficient PEC biosensing of glucose.The Schottky barrier derived from the Au@TiO2 heterostructure efficiently separates the charge carriers at the junction interfaces,thus greatly increasing the concentration and lifetime of holes left in the valence band of TiO2.The separated holes further evidently generate the active hydroxyl radicals,which can specifically recognize and oxidize glucose.As a result,Au@TiO_(2) exhibits excellent photoelectric activity and selectivity,far superior to TiO_(2) without decorated Au nanoparticles.In addition,such asymmetric Au@TiO_(2) system has been proved to feature the intrinsic flexibility nature,since its PEC biosensing performance is almost unaffected under indirect light irradiation and serious tensile strain.

Shape Memory Effect,Thermal Expansion and Damping Property of Friction Stir Processed NiTip/Al Composite

NiTi particles reinforced aluminum （NiTip/Al） composite was prepared via friction stir processing, elimi- nating interfacial reaction and/or elemental diffusion. The NiTip in the composite maintained the intrinsic characteristic of a reversible thermoelastic phase transformation even after heat-treatment. The shape memory characteristic of the NiTip decreased the coefficient of thermal expansion of the Al matrix, and an apparent two-way shape memory effect was observed in the composite. The composite owned a good combination of adjustable damping and thermal physical properties.