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Abstract: In this contribution an alternative, efficient cathode for organic light-emitting diodes (OLEDs) is introduced consisting of a sub-nanometer thin lithium phosphate (Li3PO4) layer capped with aluminium. This cathode is competitive to the LiF/Al state-of-the-art cathode and performs equally well in small molecule and polymer OLEDs but yields a higher device lifetime. The functional principle of the Li3PO4/Al cathode is based on the in situ formation of a dipolar interface. Partly oriented AlPO4 dipoles are the reason for a potential drop at the interface and a work function lowering of about 500meV. The work function of the Li3PO4/Al cathode is found to be comparable to the work function of calcium resulting in a promotion of electron injection. As the reaction products of the interface reaction are environmentally stable and chemically attached to the interface diffusion of these species into the organic layer is unlikely. This might be the reason for the observed enhanced device lifetime for devices with a Li3PO4/Al cathode. [Copyright &y& Elsevier]

Abstract: In this paper, activity coefficients of tin atoms is studied in diffusing from tin atoms to substrate surface of iron in 260∼350. The activity coefficient of tin reduced gradually with the weight percentage of tin diffused into the iron layer increased at different temperatures. The ratio of initial activity coefficients and balance activity coefficients tends to decrease.The activity coefficient decreased rapidly to near zero with the temperature and the difference of activity coefficients gradually becomes more gentle with the temperatures increasing. [Copyright &y& Elsevier]

Abstract: The rare earth zirconates have attracted interest for thermal barrier coatings (TBCs) because they have very low intrinsic thermal conductivities, are stable above 1200°C and are more resistant to sintering than yttria-stabilized zirconia (YSZ). Samarium zirconate (SZO) has the lowest thermal conductivity of the rare earth zirconates and its pyrochore structure is stable to 2200°C but little is known about its response to thermal cycling. Here, columnar morphology SZO coatings have been deposited on bond coated superalloy substrates using a directed vapor deposition method that facilitated the incorporation of pore volume fractions of 25 to 45%. The as-deposited coatings had a fluorite structure which transformed to the pyrochlore phase upon thermal cycling between 100 and 1100°C. This cycling eventually led to delamination of the coatings, with failure occurring at the interface between the TGO and a “mixed zone” that formed between the thermally grown alumina oxide (TGO) and the SZO. While the delamination lifetime increased with coating porosity (reduction in coating modulus), it was significantly less than that of similar YSZ coatings applied to the same substrates. The reduced life resulted from a reaction between the rare earth zirconate and the alumina-rich bond coat TGO, leading to the formation of a mixed zone consisting of SZO and SmAlO3. Thermal strain energy calculations show that the delamination driving force increases with TGO and mixed layer thicknesses and with coating modulus. The placement of a 10μm thick YSZ layer between the TGO and SZO layers eliminated the mixed zone and restored the thermal cyclic life to that of YSZ structures. [Copyright &y& Elsevier]

We present a thermodynamic model for reaction rim growth in a binary system containing only phases of fixed compositions. The necessary diffusion of the chemical components across the growing rim and the motion of the phase boundaries on either side of the rim are considered as the only dissipative processes involved. It is shown that for finite interface mobilities rim growth is inevitably interface reaction controlled during the initial growth stage. At a later stage a gradual transition to diffusion controlled growth occurs. Evolution equations describing this transition from linear to parabolic growth behavior are presented for planar, cylindrical and spherical geometry. [ABSTRACT FROM AUTHOR]

Effects of Cr, Al and Hf, varied from 0-32 wt.%, 1-7.5 wt.% and 0.3-1.5 wt.% respectively, on reactions between nickel base alloy melt and silicon oxide core were investigated in this paper. Role of temperature also was studied. Morphology and structures of reaction products were analyzed by scanning electron microscope (SEM) with the energy dispersive spectrometry (EDS) and the X-ray diffraction (XRD) technique. Amount of alumina in interface increased with Cr level, and formed a layer with thickness up to several microns in alloy of 32 wt.% Cr, and 1 wt.% Al. Reaction products in alloy without Hf were mainly alumina, while in alloy with Hf were mainly hafnium oxides and alumina. More hafnium oxides were formed in alloy with 1.5 wt.%Hf and 9 wt.% Cr, while more alumina formed in alloy with 0.3 wt.%Hf and 15 wt.%Cr, a double layer of reaction products formed at the temperature of 1540 °C, which were composed of a hafnium oxide layer near the metal and a alumina layer above it. The result shows that Cr, Hf levels in the alloy and reaction temperature have the effect of accelerating interface reaction. [ABSTRACT FROM AUTHOR]

Abstract: The interfacial layer formed between a lithium-ion conducting solid electrolyte, Li7La3Zr2O12 (LLZ), and LiCoO2 during thin film deposition was characterized using a combination of microscopy and electrochemical measurement techniques. Cyclic voltammetry confirmed that lithium extraction occurs across the interface on the first cycle, although the nonsymmetrical redox peaks indicate poor electrochemical performance. Using analytical transmission electron microscopy, the reaction layer (∼50nm) was analyzed. Energy dispersive X-ray spectroscopy revealed that the concentrations of some of the elements (Co, La, and Zr) varied gradually across the layer. Nano-beam electron diffraction of this layer revealed that the layer contained neither LiCoO2 nor LLZ, but some spots corresponded to the crystal structure of La2CoO4. It was also demonstrated that reaction phases due to mutual diffusion are easily formed between LLZ and LiCoO2 at the interface. The reaction layer formed during high temperature processing is likely one of the major reasons for the poor lithium insertion/extraction at LLZ/LiCoO2 interfaces. [Copyright &y& Elsevier]

The interface reaction and molecule recognition among wood flour, amino silane coupling agent and maleic anhydride grafted polyolefin compatibilizer were studied by fourier transform infrared analyzer (FTIR), scanning electron microscope with an energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray photoelectron spectra (XPS). According to molecule recognition principles, γ-APS in the wood flour surface was identified by SEM-EDS. A new state of N1 s at 401.33 eV appears in XPS as γ-APS and maleic anhydride grafted polyolefin compatibilizer are introduced simultaneously, which shows the occurrence of reaction between γ-APS and maleic anhydride-grafted polyolefin compatibilizer, and amino is formed. [ABSTRACT FROM AUTHOR]

Abstract: Wetting and capillarity have appeared over the last decadesas potential tools for the guided actuation, self-assembly and nanostructuration, and most recently as powerful “tool-free” techniques of micro-, and nano-fabrication, in the field of nanotechnology. The present work deals with such a use of wetting, achieving for the first time the spontaneous growth of composite (lipid-capped polyoxometalate) nanomembranes, using the reactive spreading film formed by the droplets of a lipid solution, on an aqueous foundation hosting the polyoxometalate ions. Moreover, we show that the internal stress produced by the reactive wetting, and the resulting self-movements of the drop could be accumulated within the drying spreading film, driving the spontaneous occurrence of wrinkles, in the freely floating nanomembranes that are thus formed. Finally, we showed that gravity-driven scaling relations for buckling instabilities apply to these spontaneously occurring wrinkles, allowing the in situ characterization of the physical properties of the nanomembranes. This approach that allowed producing floating nanomembranes of “lipid-capped Keggin ions” that were collectable as freestanding nanosheets may constitute a potential route for the fabrication of a wide range of functional (copolymers/metal nanoparticles) nanocomposite membranes. [Copyright &y& Elsevier]

Abstract: In order to investigate the effects of boron concentration on the corrosion resistance of Fe–B alloys in molten zinc, Fe–B alloys, with the boron concentrations of 1.5wt.%, 3.5wt.% and 6.0wt.% respectively, were dipped into a pure molten zinc bath at 460°C and kept in different time intervals. The results show that, in comparison with 1Cr18Ni9Ti stainless steel, Fe–B alloy with 3.5wt.%B exhibits excellent corrosion resistance, due to the dense continuous network or parallel Fe2B phase which hinders the Fe/Zn interface reaction in Fe–B alloys. The energy dispersive spectrum (EDS) results indicate that the coarse and compact δ phase with the length about 40μm generates near the matrix of Fe–B alloy and massive ζ phase occurs close to the liquid zinc. The corrosion process includes Fe/Zn reaction and the isolation and fracture of Fe2B. The failure of boride is mainly caused by the microcrack. [Copyright &y& Elsevier]

Abstract: Carbon nanotube (CNT) reinforced Ti matrix composites were synthesized using the heterogeneous coacervation method followed by spark plasma sintering (SPS). The morphology, phase structure and elevated temperature compressive properties were studied. The CNTs were well dispersed onto the Ti particles, and parts of them were converted into TiC along the interface after SPS due to solid-state reaction. However there were CNTs with original size remaining even in the composites sintered at 1000°C. The compressive yield strength declined before a slight rise with the increase in sintering temperatures, which indicated that the reinforcements and dense structure played the combined action. [Copyright &y& Elsevier]

Multi-phase composite microstructure was designed in a Ni42C0.6Mn3.5Nb3Fe50.9 invar alloy which was welded to WC-Co cemented carbide. The multi-component composition (Ni42C0.6Mn3.5Nb3Fe50.9) was chosen such that on welding of the cemented carbide to invar alloy the nonequilibrium interface reactions were suppressed. The microstructures of Ni42C0.6Mn3.5Nb3Fe50.9 invar alloy and the dissimilar materials (WC-Co and Ni42C0.6Mn3.5Nb3Fe50.9) welded joint were characterized with SEM and EDS analysis, and phase was done using x-rays diffractometer. The hardness profile is determined using micro-hardness measurements. Sound metallurgical bond and smooth hardness transition from 420HV0.2 to 870HV0.2 near interface were obtained without groove and filler materials. [ABSTRACT FROM AUTHOR]

Abstract: Nearly mono-dispersed nickel ferrite nanoparticles have been synthesized by a solid-liquid interface reaction of Ni2+Fe2 3+–oleate complex with alkali solution assisted by hydrothermal crystallization. Chemical reactions took place at the interface of the solid and liquid phase and the generated particles were then dispersed into the aqueous solution through Brownian movement. The obtained samples were characterized by X-ray diffraction and transmission electron microscopy. It was indicated that the particle size and distribution were affected by solvents, type of alkali, hydrothermal temperature and time. By finely tuning the synthesis conditions, nearly mono-dispersed nanoparticles in the range of 5–12nm could be readily prepared. The magnetism measurements showed that the nickel ferrite nanoparticles were superparamagnetism due to the nano-sized effect. [Copyright &y& Elsevier]

T700/Al and M40/Al composites were fabricated by squeeze casting technology, and their interface and mechanical properties were investigated comparatively. The results showed that both of the composites were dense, and the fibers were distributed uniformly in aluminum matrix. Aluminum carbide (Al4C3) was observed on the interface of the two carbon fiber-reinforced aluminum (Cf/Al) composites. There was little Al4C3 with a length of 300–500 nm and a width of 30–60 nm in the M40/Al composite, whereas there was a great deal of Al4C3 with a length of 200–400 nm and a width of 100–200 nm in the T700/Al composite, due to a higher graphitization of M40Cf than T700Cf. The M40/Al composite showed a much higher tensile strength than the T700/Al composite, and it was related to interfacial bonding between carbon fibers and aluminum matrices. [ABSTRACT FROM AUTHOR]

The electrical characteristics of SiC Schottky barrier diodes with laminated Mo/C electrodes having a Mo and C atom composition ratio of 2:1 have been investigated. High thermal stability against annealing up to a temperature of 1050 °C has been found as a diode characteristic. The almost identical values of Schottky barrier height for the electrons ( \varPhi \mathrm {\mathbf {Bn}}) obtained in several measurements with the ideality factors of below 1.10 indicate the formation of an ideal Schottky contact with 4H-SiC substrates. [ABSTRACT FROM PUBLISHER]

Abstract: For via structures landed on aluminum (Al) lines, ionized metal plasma (IMP) titanium (Ti) liner deposition can induce high via resistance as a result of the reaction between high energy Ti ions and the Al under-layer. The scale of the interface reaction is a function of the energy of the incoming Ti ions. A method to minimize the Ti/Al interface reaction is to introduce a thin protection layer over the Al under-layer prior to IMP Ti liner deposition. A convenient way to implement this method is to use a hybrid process, in which a Ti protection layer is first deposited in non-ionized mode prior to IMP Ti deposition. Hybrid ionized physical vapor deposition has been confirmed to be effective in minimizing the Ti/Al interface reaction during titanium deposition onto the aluminum under-layer. [Copyright &y& Elsevier]

Abstract: Nickel nanoparticles supported on metal oxides were prepared by a modified electroless nickel-plating method. The process and mechanism of electroless plating were studied by changing the active metal (Ag) loading, acidity, and surface area of metal oxides and were characterized by UV–vis spectroscopy, transmission electron microscopy, scanning electron microscopy, and H2 chemisorption. The results showed that the dispersion of nickel nanoparticles was dependent on the interface reaction between the metal oxide and the plating solution or the active metal and the plating solution. The Ag loading and acidity of the metal oxide mainly affected the interface reaction to change the dispersion of nickel nanoparticles. The use of ultrasonic waves and microwaves and the change of solvents from water to ethylene glycol in the electroless plating could affect the dispersion and size of nickel nanoparticles. [Copyright &y& Elsevier]

The application of green reductant is signification to recycling of cathode materials from spent lithium ions batteries. Here, ginkgo biloba was developed for enhancing leaching of spent LiNi 0.6 Co 0.2 Mn 0.2 O 2 materials with systematically analysis of leaching kinetics and interface reaction. The leaching efficiencies of Ni, Mn, Co, and Li reach respectively 98.65 %, 98.25 %, 98.41 % and 99.99 % under optimal condition of 1.8 mol/L H 2 SO 4 concentration, 9 g/L ginkgo biloba, 80 °C leaching temperature, 40 min time and 15 g/L pulp density. The apparent activation energies for leaching of Ni, Co, Mn and Li determined as 74.63, 79.33, 73.14 and 23.43 kJ/mol, respectively, indicates that the leaching process was controlled by the surface chemical reaction during the leaching process. Meanwhile, the regenerated material with better electrochemical performance was obtained by co-precipitation and calcination from leachate. Finally, the process is environmental friendly and economical feasible for recycling of spent lithium-ion batteries. [Display omitted] • Ginkgo biloba was novelly applied in enhancing leaching of spent cathode material. • Leaching kinetics was analyzed for clarifying the controlling step. • The interface reaction of spent cathode materials in leaching system was analyzed. • The closed loop process was developed for recycling of spent cathode materials. [ABSTRACT FROM AUTHOR]

Abstract: Selection of metal matrix of Grf/Al composites is very important to improve properties of composites. M40 carbon fiber-reinforced aluminum composites (Grf/Al) with different matrix were fabricated by a pressure infiltration method. Fracture surfaces were characterized by scanning electron microscopy (SEM), while the microstructure was investigated by transmission electron microscopy (TEM). With the increase of Mg content, the formation of brittle Al4C3 phase is suppressed, which results in an intermediate interface bonding, therefore improves the mechanical properties of composites. [Copyright &y& Elsevier]

The most pertinent coating materials in the Al−Ti−Cr alloy system to improve the high temperature oxidation resistance of a TiAl alloy, with respect to oxidation properties, resistance to thermal stress, and chemical compatibility, are the two-phase alloys of Al−21Ti−23Cr (L12+Cr2Al) and Al−37Ti−12Cr (γ+TiAlCr). In this study, cyclic oxidation tests at 1000 °C and 1200 °C were performed for the specimens coated with both materials of 10 im thickness. Furthermore, breakaway oxidation caused by the formation of a rutile TiO2 scale was observed, though both bulk alloys showed very stable oxidation behavior. This phenomenon was resulted from the depleted Al content in the coating layer due to Al2O3 oxide growth and interdiffusion with the substrate. Considering the decrease of Al content due to oxide growth, the Al−21Ti−23Cr coating with the initial higher Al content was more effective for long-term oxidation protection of the TiAl alloy. On the other hand, when the Al content changes due to the interdiffusion with the substrate, the Al−37Ti−12Cr coating with a smaller compositional gradient with the TiAl substrate was more effective than the Al−21Ti−23Cr coating. Cyclic oxidation tests at 1000 °C and 1200 °C confirmed that for the longer lifetime of coating materials the initial Al content was more important than the smaller compositional gradient with the substrate. Consequently, the Al−21Ti−23Cr coating was considered as more effective one for the long-term oxidation resistance of TiAl alloys. [ABSTRACT FROM AUTHOR]

Abstract: Active brazing is an effective technique for joining diamond or cBN grit to metallic substrates. This technique is currently used to manufacture superabrasive, high-performance tools. The investigation of interface reactions between diamond and active brazing alloys plays an important role in understanding and improving the brazing process and the resultant tool performance. Focused ion beam (FIB) milling enabled the high resolution investigation of these extremely difficult to prepare metal–diamond joints. The interfacial nanostructure is characterized by the formation of two layers of TiC with different morphologies. First a cuboidal layer forms directly on the diamond and reaches a thickness of approximately 70nm. Then a second layer with columnar TiC crystals grows on the first layer into the brazing filler metal by a diffusion-controlled process. The combined thickness of both TiC layers varies between 50nm and 600nm depending on the brazing temperature and holding time. [Copyright &y& Elsevier]

Abstract: Cation transport behavior through the lanthanum strontium cobaltites, La1−xSrxCoO3 (LSC)/lanthanum strontium ferrite, La0.8Sr0.2FeO3 (LSF) interface was examined by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Diffusion couples made of La0.8Sr0.2FeO3 (LSF82) and LSCs with different Sr contents (x =0.1 : LSC91, x =0.2 : LSC82 and x =0.5 : LSC55), were treated at 1373 K in air. It has been observed that faceted particles of spinel type CoFe2O4 were precipitated at a detached interface of the LSF82 pellets in the LSC91/LSF82 and LSC82/LSF82 diffusion couples. For the LSC55/LSF82 couple, cobalt oxide particles were precipitated on the LSF82 surface, while the formation of a Sr rich phase was observed on the LSC55 surface. It has been found that the interface stability of the LSC/LSF diffusion couples strongly depends on the La/Sr composition at the A site of the La1−x Sr x CoO3 perovskite compounds. [Copyright &y& Elsevier]

Abstract: We investigated the optimum structure for Ti-containing Hf-based high-k gate dielectrics to achieve EOT scaling below 1nm. TiO2/HfSiO/SiO2 trilayer and HfTiSiO/SiO2 bilayer structures were fabricated by a newly developed in-situ PVD-based method. We found that thermal diffusion of Ti atoms to SiO2 underlayers degrades the EOT–J g characteristics. Our results clearly demonstrated the impact of the trilayered structure with TiO2 capping for improving EOT–J g characteristics of the gate stack. We achieved an EOT scaling of 0.78nm as well as reduced gate leakage of 7.2×10−2 A/cm2 for a TiO2/HfSiO/SiO2 trilayered high-k dielectric while maintaining the electrical properties at the bottom interface. [Copyright &y& Elsevier]

Abstract: The fiber/matrix interfaces developed in continuous carbon fiber (CF) and graphite fiber (GRF) reinforced 2014 aluminum matrix composites were characterized using scanning and transmission electron microscopy (TEM). The as-cast CF/2014 Al and GRF/2014 Al composite specimens were processed by pressure infiltration of continuous fiber bundles preheated at 500°C, while the fiber reinforcements were externally cooled during infiltration by exposing fiber ends to atmospheric air. Very limited precipitation of secondary phases along the fiber matrix interface was observed in the microstructure. Most of the secondary phases identified in the matrix in the interfiber regions included Al20Cu2Mn3, AlSiMnFe or Al2Cu within interfiber regions. Other interfacial reaction products detected were Cu- and Si-based spinels in the CF composite and an amorphous Al–C–O layer in the GRF composite. In both composites, Al4C3 was detected but its frequency of occurrence was rather low, particularly in the GRF composite interfaces. The formation of relatively clean GRF/matrix interfaces in the GRF composite suggests nucleation of primary alpha-aluminum phase on some parts of graphite fiber surface; the orientation relationship between GRF and aluminum appears to be (020)Al//(0002)GRF in the present study. [Copyright &y& Elsevier]

Abstract: The behavior at the air–water interface of amphiphilic α, β and γ trimethylsilyl per-modified cyclodextrin (pTMS-CD) monolayers is reported, as a first step towards the building up of a Langmuir–Blodgett assembly with potential gas sensor properties. The pTMS-CDs form stable monolayers with unusually high collapse pressure. It is shown that this peculiar behavior arises from a partial hydrolysis of TMS groups at the air–water interface. This hydrolysis reaction was confirmed by infrared spectroscopy and the departure of TMS groups was evidenced by weight loss measurements through quartz crystal microbalance carried out on the pTMS-CD monolayers deposited through the Langmuir–Blodgett technique. [Copyright &y& Elsevier]

Abstract: NiCrAlY coating was deposited on TC4 (Ti–6Al–4V) titanium alloy substrate by arc ion plating (AIP). After vacuum heat treatments, the microstructures and microhardness of the NiCrAlY coating were characterized by using scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS), X-ray diffraction (XRD), and Vickers hardness test. The formation of interfacial products and the behavior of Cr element in TC4 substrate/NiCrAlY coating interface reactions were also studied. The results show that γ′-Ni3Al phase precipitated in NiCrAlY coating after heat treatment, which increased the microhardness of the coating. After vacuum heat treatments under 870°C, the effected zone, Ti2Ni layer, TiNi layer, and Ni3(Al, Ti) layer appeared in turn from inside to outside at the interface between TC4 substrate and NiCrAlY coating. When the vacuum heat treatment temperature was above 870°C, the Cr element began to diffuse and then reacted with Ti to form TiCr2. [Copyright &y& Elsevier]

Abstract: We have made a detailed investigation of structure and chemical composition in thermally grown Al/Alq3/ITO layer structures intended for light emission. The different parts of the structure were studied by X-ray photoelectron spectroscopy and microscopical techniques. The indium tin oxide substrate surface consisted of grains 20–50nm in diameter and ∼5nm in height, which also showed molecular sized sub-grain features. Due to the ambient the ITO surface was covered by a ∼1nm thick hydrocarbon layer which serves as the actual surface on which an organic layer is deposited for device fabrication. A structural model for the indium tin oxide surface, on which the small molecules were deposited, was suggested. The substrate surface was treated to study the relation between the surface manipulation and the hole injection barrier. Such surface modification significantly improved the performance of a single layer Alq3 organic light emitting diode. Depth profiling of the complete structure, revealed that the aluminium contact mostly consisted of aluminium oxide with some intermixing of carbon. Further, variations of the atomic concentration of the elements In, Sn, C and O and a minor shift in their binding energies were measured. Both, position and shape of the oxygen and indium peaks were changed during argon ion sputtering. At the Alq3/ITO interface an indium–oxygen compound, different from that on the original surface, had formed. Various effects of the compositional findings on the light emission are discussed. [Copyright &y& Elsevier]

Abstract: Interactions between metals and oxides are key factors to determine the performance of metal/oxide heterojunctions, particularly in nanotechnology, where the miniaturization of devices down to the nanoregime leads to an enormous increase in the density of interfaces. One central issue of concern in engineering metal/oxide interfaces is to understand and control the interactions which consist of two fundamental aspects: (i) interfacial charge redistribution — electronic interaction, and (ii) interfacial atom transport — chemical interaction. The present paper focuses on recent advances in both electronic and atomic level understanding of the metal–oxide interactions at temperatures below 1000 ∘C, with special emphasis on model systems like ultrathin metal overlayers or metal nanoclusters supported on well-defined oxide surfaces. The important factors determining the metal–oxide interactions are provided. Guidelines are given in order to predict the interactions in such systems, and methods to desirably tune them are suggested. The review starts with a brief summary of the physics and chemistry of heterophase interface contacts. Basic concepts for quantifying the electronic interaction at metal/oxide interfaces are compared to well-developed contact theories and calculation methods. The chemical interaction between metals and oxides, i.e., the interface chemical reaction, is described in terms of its thermodynamics and kinetics. We review the different chemical driving forces and the influence of kinetics on interface reactions, proposing a strong interplay between the chemical interaction and electronic interaction, which is decisive for the final interfacial reactivity. In addition, a brief review of solid–gas interface reactions (oxidation of metal surfaces and etching of semiconductor surfaces) is given, in addition to a comparison of a similar mechanism dominating in solid–solid and solid–gas interface reactions. The main body of the paper reviews experimental and theoretical results from the literature concerning the interactions between metals and oxides (TiO2, SrTiO3, Al2O3, MgO, SiO2, etc.). Chemical reactions, e.g., redox reactions, encapsulation reactions, and alloy formation reactions, are highlighted for metals in contact with mixed conducting oxides of TiO2 and SrTiO3. The dependence of the chemical interactions on the electronic structure of the contacting metal and oxide phases is demonstrated. This dependence originates from the interplay between interfacial space charge transfer and diffusion of ionic defects across interfaces. Interactions between metals and insulating oxides, such as Al2O3, MgO, and SiO2, are strongly confined to the interfaces. Literature results are cited which discuss how the metal/oxide interactions vary with oxide surface properties (surface defects, surface termination, surface hydroxylation, etc.). However, on the surfaces of thin oxide films grown on conducting supports, the effect of the conducting substrates on metal–oxide interactions should be carefully considered. In the summary, we conclude how variations in the electronic structure of the metal/oxide junctions enable one to tune the interfacial reactivity and, furthermore, control the macroscopic properties of the interfaces. This includes strong metal–support interactions (SMSI), catalytic performance, electrical, and mechanical properties. [Copyright &y& Elsevier]

An accelerated L10 ordering process was observed in FePt thin films deposited directly on HF-cleaned Si substrates at low annealing temperatures as compared with those deposited on nature-oxidized Si substrates, which results from an interface reaction that forms PtSi between the FePt film and the Si substrate. The L10 ordered FePt thin films prepared after 360°C annealing show a large coercivity of H c =8.9kOe and an excellent stability against thermal annealing. [Copyright &y& Elsevier]

Strontium tungstate nanorods with uniform morphology were controllably synthesized for the first time via a facile liquid–solid–solution (LSS) process through oil/water interface. These nanorods have diameters of about 50 nm and length of about 500 nm. XRD curves indicated that as-obtained nanorods were body-centered tetragonal phases with lattice parameters of a = 5.416 Å and c = 11.95 Å, which is consistent with the values reported in JCPDS card No. 08-0490. Study on the optical properties of as-obtained nanorods showed that SrWO4 nanorods possess different optical properties from bulk counterpart. A mechanism of the formation process was also discussed. [ABSTRACT FROM AUTHOR]

Abstract: We have studied ion-induced modifications of aluminum nitride (AlN) thin films with (110) orientation of wurtzite crystal structure, which were grown on R(11–20 surface-cut)-Al2O3 substrates. For 100keV N ion irradiation at a fluence of 1017 cm−2, we have observed the increase (14nm) of the film thickness by means of Rutherford backscattering spectroscopy (RBS) and optical reflectivity spectroscopy with the measured refractive index. Here, the film thickness before ion irradiation is approximately 200nm and comparable with the calculated mean projected-range (183nm) of 100keV N ions using TRIM97 simulation code. These results can be understood as the reaction of nitrogen with Al, i.e. formation of AlN near the film-to-substrate interface (interface reaction). Modifications of optical and structural properties by ion irradiation are presented. [Copyright &y& Elsevier]

Abstract: We systematically investigated intrinsic and extrinsic thermal reactions at TiN/HfSiON gate stacks. The formation of an ultrathin TiO2 interlayer was found to be an intrinsic reaction at the metal/insulator interface, but growth of SiO2 underlayers between HfSiON and Si substrates, which determines the electrical thickness of metal-oxide-semiconductor (MOS) devices, depends on the structure and deposition method of the gate electrodes. Physical vapor deposition (PVD) grown TiN electrodes covered with W overlayers exhibited excellent thermal stability at up to 1000°C. Formation of ultrathin TiO2 interlayers reduced gate leakage current (I g), and growth of the oxide underlayer was suppressed by less than a few angstroms even for 1000°C annealing. In contrast, we found that halogen impurities within CVD-grown metal electrodes enhance interface SiO2 growth, resulting in deterioration of equivalent oxide thickness (EOT) versus I g characteristics of the gate stacks. [Copyright &y& Elsevier]

The interface reactions between transition metal oxide substrates and ultra thin metal layers of different thickness (<15 nm) have been investigated by using x-ray photoelectron spectroscopy (XPS). To a different extent oxidation of deposited metal and reduction of the oxidic substrate is visible for complementary layer systems. For the interface nickel oxide/manganese an enhanced reaction is found compared to the system manganeseoxide/nickel. Based on the experimental data a model of the evolving interface is proposed. [ABSTRACT FROM AUTHOR]

Abstract: The duplex oxide film potentiostatically formed on copper in concentrated alkaline media has been investigated by XRD, XPS, negative-going voltammetry and cathodic chronopotentiometry. The interfacial capacity was also measured using fast triangular voltage method under quasi-stationary condition. The obvious differences in the thickness, composition, passivation degree and capacitance behavior were observed between the duplex film formed in lower potential region (−0.13 to 0.18V versus Hg|HgO electrode with the same solution as the electrolyte) and that formed in higher potential region (0.18–0.60V). Cuprous oxides could be formed and exist stably in the inner layer in the both potential regions, and three cupric species, soluble ions and Cu(OH)2 and CuO, could be independently produced from the direct oxidation of metal copper, as indicated by three pairs of redox voltammetric peaks. One of the oxidation peaks appeared only after the scan was reversed from high potential and could be attributed to CuO formation upon the pre-accumulation of O2− ions within the film under high anodic potentials. A new mechanism for the film growth on the investigated time scale from 1 to 30min is proposed, that is, the growth of the duplex film in the lower potential region takes place at the film|solution interface to form a thick Cu(OH)2 outer layer by field-assisted transfer of Cu2+ ions through the film to solution, whereas the film in the higher potential region grows depressingly and slowly at the metal|film interface to form Cu2O and less CuO by the transfer of O2− ions through the film to electrode. [Copyright &y& Elsevier]

Compounds of ground tyre rubber (GTR) and polypropylene (PP) were prepared in an internal mixer and characterised by means of mechanical, thermal and morphological testing. Only physical melt mixing could not provide a suitable interface compatibilisation and leads to compounds with poor mechanical properties. However, the application of a reactive melt mixing process, using organic peroxides as radical donators, was found to be suitable to initiate a compatibilisation reaction via interphase grafting. These compatibilised GTR/PP elastomeric alloy (EA) systems exhibit interesting mechanical properties which are close to that of conventional two phase thermoplastic elastomers (TPE) based on dynamically vulcanised ethylene propylene diene monomer (EPDM)/PP blends. Results of the morphology investigations substantiate the occurrence of a compatibilisation reaction between rubber particles and PP matrix during reactive mixing which is most probably responsible for the enhanced material properties of the GTR/PP EA. [ABSTRACT FROM AUTHOR]

Abstract: In order to explore the mechanism of reactive wetting occurred between solder and Cu substrate, the wetting behavior of high-Pb, say, Pb-xSn solder (x =0, 0.7, 1.4, 2.1, 2.8, and 3.5wt.%, respectively) was investigated using the wetting balance technique. It was found that small amount of addition Sn in Pb could improve the wettability of Pb-xSn solder on Cu severely. Since the current reactive wetting theory suggested that the first intermetallic compound formed during the wetting reaction could influence the wetting properties, the driving forces of the intermetallic compounds formation under metastable equilibrium were calculated using Thermo Calc software. And the first intermetallic compound was confirmed to be Cu3Sn by both theoretical computation and EDX analysis. The reactive wetting theories was employed, and combined with the analysis of wetting balance test results, to discuss the wetting phenomena herein. [Copyright &y& Elsevier]

The effects of Al and silicon additions to Cu based brazing alloy and the surface free silicon on siliconised graphite substrate on the wetting behaviour of the siliconised graphite by Cu–Al–Si–Ti alloys were investigated using the sessile drop technique at 1100°C. The contact angles were measured and the interfacial reactions were analysed. It was shown that surface free Si on siliconised graphite had a great positive effect on the contact angle. Furthermore, interfacial reactions could be controlled by adjusting the contents of Si and Al in brazing alloys. [ABSTRACT FROM AUTHOR]

The interface reaction between the SiC particles (SiCp) and Fe was studied during sintering the SiCp reinforced Fe matrix composites at 1423 K for 1 h. In the composite having 3wt% (weight ratio) SiCp (the 3SiCp/Fe composite), the interface reaction products of Fe3Si, the carbon precipitates, and Fe3C or pearlite were generated. Fe3Si constructs the bright matrix of the reaction zone in the original situation of the SiCp. The carbon precipitates, are randomly embedded in the reaction zone. Fe3C or pearlite exists at the grain boundaries of the Fe matrix. As increasing the SiCp concentration in the SiCp/Fe composite, the intensity of the interface reaction between SiCp and Fe increases. After the 10SiCp/Fe composite (having 10wt. % SiCp) sintered at 1423 K for 1 h, all of SiCp are decomposed, and replaced by the reaction zone composed of Fe3Si and the carbon precipitates. No Fe3C or pearlite was generated during the reaction. The effects of the techniques of oxidizing of SiCp, coating SiCp by interaction with the Cr powder, and alloying the Fe matrix by adding the Cr element on the interface stability of the SiCp/Fe composite system were also investigated, respectively. The oxide membrane and the coating layer on SiCp can inhibit the interface reaction between SiCp and Fe by isolating SiCp from the Fe matrix during sintering. The interface reaction does not occur in the 3 SiCp/Fe-10Cr composite but in the 3 SiCp/Fe-5 Cr composite. In the SiCp/Fe−Cr alloy composites, the interface reaction between SiCp and the Fe−Cr alloys is weaker than, that between SiCp and Fe. The Cr element behaves as a diluent, it causes a reduction in the interface reaction, which is proportional to the amount of the element added. [ABSTRACT FROM AUTHOR]

Abstract: We have measured depth profiles of N isotopes by Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA) before and after implantation of 100keV N isotopes into Si3N4 films on SiO2-glass substrates, which were prepared by using RF-magnetron-reactive-sputtering deposition method in N2 gas. The film thickness is ∼200nm and comparable with the calculated projected range, 180nm (TRIM1997) of 100keV N ions. We find that the nitride film thickness has increased after N implantation with nearly stoichiometric composition. Optical absorption spectra also show the increase of the film thickness. According to NRA, the implanted 15N are found to be located around the Si3N4 film–substrate interface. It also appears that the increase of the film thickness multiplied by the film density approximately equals to the implantation dose. These results imply reaction of implanted nitrogen with the substrate and growth of Si3N4. [Copyright &y& Elsevier]

Abstract: This investigation discovers a discrete metallic alloy layer containing Ni, Ti, and Ba between Ni and BaTiO3 co-fired in reducing atmospheres at ∼1300°C along with an oxygen-depleted zone in BaTiO3 adjacent to the metallic layer. Using high-resolution transmission electron microscopy and electron energy-loss spectroscopy, detailed structural and chemical analyses of the metallic layer are carried out. With complementary thermodynamic approximations, these observations render an assessment of the local effective oxygen partial pressure, which is considerably lower than the external, ambient processing environment. Through a set of model experiments on Ni–BaTiO3–carbon composites, we illustrate that the presence of carbon is sufficient to reduce locally BaTiO3 and form the observed metallic layer at ∼1300°C. A phase stability analysis indicates that the formation of the Ba and Ni–Ti liquid phases provides a kinetic path for the interfacial reaction. [Copyright &y& Elsevier]

Abstract: This work studied the formation of highly reactive species in the interface of Fe0/iron oxides mixtures, i.e. Fe3O4 (magnetite), γ-Fe2O3 (maghemite) or α-Fe2O3 (hematite) prepared by mechanical grinding and thermal treatment at 200, 400, 600 or 800°C under argon atmosphere. Mössbauer spectroscopy, powder X-ray diffraction, scanning electron microscopy, BET surface area and magnetization measurements suggest a strong interaction between the metal and the oxide surfaces at temperature as low as 200°C, producing highly reactive surface species. These reactive species are readily oxidized when exposed to air at room temperature to form large quantities of Fe2O3. The treatment at 600 and 800°C leads to an extensive solid state reaction of Fe0 with Fe3O4 to produce the phase wüstite, FeO, with a strong decrease in BET surface area and reactivity. These thermally treated mixtures Fe0/iron oxides were also studied as heterogeneous catalysts to promote the decomposition of H2O2. The mixtures Fe0/Fe3O4 treated at 200 and 400°C showed a remarkable increase in activity for the H2O2 decomposition. The high reactivity of these samples is discussed in terms of Fesurf 2+ species formed by electron transfer from Fe0 to Fe3+ at the interface metal/oxide which are active to initiate the H2O2 decomposition via a Haber–Weiss mechanism. The mixtures Fe0/γ-Fe2O3 and Fe0/α-Fe2O3 ground and thermally treated were also studied, however much lower activities for the H2O2 decomposition were observed. [Copyright &y& Elsevier]

Abstract: Electrochemical cells formed by the interface between dense and porous lanthanum strontium manganate (LSM) and yttria stabilized zirconia (YSZ) were submitted to annealing temperatures varying from 1373K to 1673K for 200h and studied by Impedance Spectroscopy (IS) in order to investigate how the high annealing temperature can modify the contact between LSM/YSZ and to which extension these changes influence the electrical behavior of dense and porous LSM electrodes before and after the formation of insulating phases. Up to 1473K the annealing process did not lead to substantial electrical behavior modifications at the LSM/YSZ interfaces for both porous and dense electrodes. IS measurements show two capacitive semicircles, the best fitting of impedance data brings to an equivalent circuit constituted by a serial combination of the electrolyte resistance and two parallel combinations of a resistance and a constant phase element, CPE. The higher frequency semicircles, HF, were attributed to the diffusion of oxide ions from the interface LSM/YSZ to the oxide ion vacancies located at the electrolyte surface. The semicircle at lower frequency, LF, will be ascribed to the oxygen species adsorption and diffusion in the LSM. At 1473K the only changes recorded are related with the sinterization process of the porous electrodes. Over of 1473K, the resistance contributions increased largely, especially for porous electrodes, and one additional semicircle was observed. This semicircle was associated to the oxygen diffusion process at the new insulating phases formed from YSZ and LSM solid state reactions. Porous and dense electrodes exhibited different rates for the degradation process. The porous electrode degraded faster than the dense one, probably because of the morphological effects as grain growth and their coalescence during annealing at higher temperatures. [Copyright &y& Elsevier]

Purpose: The influence of the osteotome technique on the interface reaction of cylinder implants (SLA, ITI®) was compared with the interface reaction of conventional implant insertion in an animal model. Material and methods: A total of 64 implants were placed in the cranial and caudal tibia of 8 Göttinger minipigs. The implant site was prepared either by a conventional technique with drills (control group A) or by the osteotome technique (experimental group B). Bone tissue responses were evaluated by histomorphometry, fluorescence microscopy and scanning electron microscopy after 7 and 28 days of osseointegration. Results: The average initial (7 days) bone-to-implant contact ratio was not statistically significantly different for the osteotome technique (35.88±2.94%) than for the control group (43.78±3.39%, P<0.095). After 28 days, the bone-to-implant contact ratio became statistically significantly higher when implants were inserted by conventional preparation (44.81±3.07% (group B), 63.47±4.87% (group A), P=0.003). Whereas fluorescence and immunhistologic examination revealed new bone formation with osteocalcin deposition directly at the implant surface in both groups, the extent of direct bone/implant contact was enhanced in conventionally prepared implant sites. SEM analysis confirmed an intimate bone to implant bond without fibrous tissue formation in places of direct contact at an ultrastructured level. Conclusion: Implant placement in conventionally prepared implantation sites is accompanied by an improved interface formation at an early stage of implantation. [ABSTRACT FROM AUTHOR]

Abstract: Ta/Ni81Fe19, Ni81Fe19/Ta, Cu/Ni81Fe19, and Ni81Fe19/Cu structures are commonly used in the magnetic multilayers with giant magnetoresistance. For a Ta/Ni81Fe19/Ta fundamental structure, Ta seed and Ta cap layers result in a loss of moment equivalent to a magnetically dead layer of thickness 1.6±0.2 nm. Experimental results show that a chemical reaction between Ta and Ni81Fe19 takes place at the Ta/Ni81Fe19 and Ni81Fe19/Ta interfaces. The thickness of the magnetically dead layer was significantly reduced by the insertion of a small amount of Bi in the Ta/Ni81Fe19/Ta structure (i.e. Ta/Bi/Ni81Fe19/Ta). This result indicates that Bi acts as a surfactant that can suppress the interface reaction in multilayers. For a Cu/Ni81Fe19/Cu film, permalloy layers have hardly lost their magnetic moment since interface reactions at the Cu/Ni81Fe19 interface or Ni81Fe19/Cu interface hardly occurs. [Copyright &y& Elsevier]

A number of model Ni based superalloy bimetallic discs have been manufactured, each having a cast and wrought U720Li hub bonded to a cast IN738LC ring by means of hot isostatic pressing augmented by isothermal forging. The microstructures of both the as hipped and HIP plus forged model discs showed a complex precipitation reaction at the interface between the two alloys. Different types of precipitate were identified at the bond line, which had formed as a consequence of interdiffusion and recrystallisation at the interface during hipping. Residues from a pre-HIP acid cleaning process were also detected. Preliminary forging trials conducted on the model discs found poor control of the deformation and shape of the interface due to temperature and die lubrication issues and resulted in strong recrystallisation of the IN738LC and internal cracking. Subsequent full scale disc manufacture was able to overcome these problems, although further work is continuing in the microstructural and mechanical characterisation of these parts. [ABSTRACT FROM AUTHOR]

A Ni/amorphous SiC (a-SiC) multilayered sample was prepared by ion-beam sputtering and was used as a model system to study the stability of metal contacts with a-SiC against interface reactions. The diffusion of Ni into the a-SiC layer as well as Si and C into the Ni layer takes place concurrently during the annealing process. An intermediate NiSi phase was identified in the Ni solution layer because of diffusion of Si and C resulting from the decomposition of a-SiC. A phase selection diagram has been developed that accounts for nucleation of the NiSi phase from the Ni solution layer. [ABSTRACT FROM AUTHOR]

Abstract: An asphalt–salt mixture (ASM), which once caused a fire and explosion in a reprocessing plant, was prepared by imitating the real bituminization process of waste on a lab scale to evaluate its actual thermal hazards. Heat flux reaction calorimeters were used to measure the release of heat for the simulated ASM at a constant heating rate and at a constant temperature, respectively. Experimental results show that the reaction in the ASM below about 250°C is a slightly exothermic interface reaction between the asphalt and the salt particles contained in the asphalt, and that the heat release rate increases sharply above about 250°C due to melting of the salt particles. The reaction rates were formulated on the basis of an assumed reaction model, and the kinetic parameters were determined. Using the model with the kinetic parameters, temperature changes with time and drum-radius axes for the ASM-filled drum were numerically simulated assuming a one-dimensional infinite cylinder system, where the drum was being cooled at an ambient temperature of 50°C. The minimum filling temperature, at which the runaway reaction (MFTRR) can occur for the simulated ASM in the drum is about 194°C. Furthermore, a very good linear correlation exists between this MFTRR and the initial radius of salt particles formed in the bituminization product. The critical filling temperature to the runaway reaction is about 162°C for the asphalt–salt mixture, containing zero-size salt particles, filled in the same drum at an ambient temperature of 50°C. Thus, the runaway reaction will never occur in the drum filled with the asphalt–salt mixture under the conditions of the filling temperature below 162°C and a constant ambient temperature of 50°C. As a consequence, the ASM explosion occurred in the reprocessing plant likely was due to a slightly exothermically reaction and self heating. [Copyright &y& Elsevier]

Abstract: We report on the structural and electrical properties of Pr-based high-k dielectric films fabricated by solid-state reaction between metallic Pr and SiO2 underlayers. A non-destructive depth profiling using synchrotron radiation excited photoelectron spectroscopy (SR–PES), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) were employed to examine the chemical composition and microstructure. Ab initio calculations were done to gain insight into the physical processes involved. SR-PES results indicate that Pr deposition at room temperature (RT) leads to the formation of a Pr silicide and a Pr oxide, what is in good agreement with the scenario expected from ab initio calculations. As revealed by TEM and electrical measurements, oxidation of the reacted structures, followed by annealing, results in a stacked dielectric composed of a SiO2-based buffer with an enhanced permittivity and a Pr silicate film with a high dielectric constant. The leakage current density of 10-4A/cm2 was measured for stacks with capacitance equivalent thickness (CET) of 1.5nm prepared by evaporation of the Pr layer on a 1.8nm SiO2 film, followed by oxidation in air ambient and annealing in N2 atmosphere. The capacitance-voltage (C–V) curves exhibit a large flatband voltage (VFB) shift indicating the presence of a positive charge in the stack. Switching away from the Al contacts to Au gate electrodes introduces a significant reduction of the VFB by 1.3eV, what is much more than the change expected from the work function difference between Al and Au (∼0.9eV). This in turn implies that VFB is strongly affected by the gate interface electrode. [Copyright &y& Elsevier]

A new processing route for the replication of high aspect ratio microstructures from a silicon wafer into a bulk metallic glass is presented. The approach bases on a casting process with separation of mold filling and quenching in time. Therefore a Zr-based bulk glass forming melt is applied onto a surface microstructured silicon mold with a protective layer, both at a temperature high enough to allow complete wetting of the wafer by the melt. Given enough time, open channels of high aspect ratios are completely filled by the melt which spreads over the wafer. From this state, the mold and the melt are quenched at a rate high enough to suppress crystallization of the glass forming melt. The resulting surface microstructured part out of bulk metallic glass with a high strength, a high elastic limit and good corrosion and abrasion resistance ideally meets the requirements of polymer microinjection molding tools. The wetting behavior of the Zr-based melt on the protective layer and the stability of the protective layer against dissolution in the melt are crucial to this new process and are studied for the alloy Zr52.5Cu17.9Ni14.6Al10Ti5 and silicon wafer molds with different silicon oxide protective layers. [Copyright &y& Elsevier]

ZnS films were grown by molecular beam epitaxy employing a single compound effusion cell on GaP(0 0 1) substrate at different temperatures, and characterised by means of low energy electron diffraction, X-ray and ultra-violet photoelectron spectroscopy, angle-resolved ultra-violet photoelectron spectroscopy and X-ray emission spectroscopy. The GaP(0 0 1) substrate exhibits a (4×2) reconstruction after Ar ion sputtering and annealing at 370 °C. Crystal quality of the ZnS films depends on both film thickness and growth temperature. Thinner films grown at higher temperatures and thicker films grown at lower temperatures have better crystal quality. The layer-by-layer growth mode of the ZnS films at lower (25, 80 and 100 °C) temperatures changes to layer-by-layer-plus-island mode at higher temperatures (120, 150 and 180 °C). A chemical reaction takes place and is confined to the interface. The valence band offset of the ZnS–GaP heterojunction was determined to be 0.8±0.1 eV. Sulphur L2,3 emission spectra of ZnS powder raw material and the epitaxial ZnS films display the same features, regardless of the existence of the Ga&z.sbnd;S bonding in the film samples. [Copyright &y& Elsevier]