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The temperature dependences of the composition of the outer monolayers of the surface of thermoemitters, namely, oxide, scandate, thoriated tungsten, and carbide cathodes, have been studied by the methods of low-energy ion and recoil atom scattering, Auger spectroscopy, and secondary ion mass spectroscopy. It has been established that the surfaces of oxide, scandate, and tungsten-thorium cathodes at operating temperatures contain a monoatomic film of active material (barium, thorium), which forms on the surface of the emitter when heated to operating temperature and dissolves in volume when the temperature drops to room temperature. As a result of activation, free barium accumulates in the volume of oxide crystals. It is shown that there is a slight increase in tantalum on the surface of tantalum carbide and it contains foreign electronegative adatoms (oxygen, chlorine, and sulfur) that cannot be removed at temperatures of 2500 K. [ABSTRACT FROM AUTHOR]

The article presents the results of a study of vacuum-arc coatings obtained by the sputtering of Ti–B–Si–Ni cathodes fabricated using self-propagating high-temperature synthesis with simultaneous pressing. The techniques for manufacturing cathodes of the indicated composition are characterized; the modernized HNV 6.6-I1 installation, the conditions and modes of coating deposition in an argon atmosphere and in a nitrogen + argon gas mixture in the ratio of 90/10 are described. To study the physical and mechanical properties of the resulting coatings, the hardness is measured at different loads on the indenter; the strength of adhesion to the base is assessed by the Rockwell method; the elemental composition of the cathodes and the (Ti–B–Si–Ni)N coating is determined using Auger spectroscopy, and the phase composition of the (Ti–B–Si–Ni)N coating is determined using X-ray phase analysis; a study of the properties of the coating (Ti–B–Si–Ni) is carried out by scratch testing. As a result of a comprehensive analysis of the results obtained, it is concluded that the high hardness of the (Ti–B–Si–Ni)N coating (more than 40 GPa) is due to its composition, which includes both nitrides and high-hardness titanium borides. The heterophase nature of the structure of this coating can serve as a contribution to the stressed state of the material. The coating has a graded-layer structure. The material contains a Ti–B–Si–Ni layer bound to the substrate and the main functional layer (Ti–B–Si–Ni)N. The coating has both a high hardness and sufficient strength of adhesion to the base (adhesion) determined by scratch testing. The combination of these properties makes the material promising for its practical application in the production of tools. [ABSTRACT FROM AUTHOR]

This paper reviews a procedure that allows for extracting primary photoelectron or Auger electron emissions from homogeneous isotropic samples. It is based on a quantitative dielectric description of the energy losses of swift electrons travelling nearby surfaces in presence of stationary positive charges. The theory behind the modeling of the electron energy losses, implemented in a freely available QUEELS-XPS software package, takes into account intrinsic and extrinsic effects affecting the electron transport. The procedure allows for interpretation of shake-up and multiplet structures on a quantitative basis. We outline the basic theory behind it and illustrate its capabilities with several case examples. Thus, we report on the angular dependence of the intrinsic and extrinsic Al 2s photoelectron emission from aluminum, the shake-up structure of the Ag 3d, Cu 2p, and Ce 3d photoelectron emission from silver, CuO and CeO2, respectively, and the quantification of the two-hole final states contributing to the L3M45M45 Auger electron emission of copper. These examples illustrate the procedure, that can be applied to any homogeneous isotropic material. [ABSTRACT FROM AUTHOR]

Oils and iron fines deposit on carbon steel during cold rolling and are removed by an electrolytic cleaning line (ECL). Sometimes localized contamination is observed on the ECL samples. No reliable tests are available for on-line measurement and the off-line tests demand samples with a large surface area. SKP addresses this issue effectively. SKP shows ∼390 mV potential difference between the clean and the uncleaned surface, with the cleaned surface potential being more positive. This indicates that the oil on the steel acts as a Lewis base, whereas the steel surface acts as a Lewis acid. Hence, the potential of the sample increases after cleaning. FTIR confirmed the absence of oil peaks on the cleaned samples. Deposition of an optimum thickness of the silicate layer is another important aspect of the ECL. It was measured by AES which displayed 2.3 nm of the silicate layer deposited on the cleaned steel surface. [ABSTRACT FROM AUTHOR]

The effect of changing the terminal functional group of C7 and C8 carboxylate species adsorbed on copper on the rate of tribochemical decomposition is investigated both in an ultrahigh vacuum tribometer and using an atomic force microscopy (AFM) tip, where the conditions are selected to provide similar normal stresses for both experiments. The carbon chains are terminated by alkyl, vinyl and acetylide groups, where the different chain lengths are selected to modify the orientation of the terminal π-orbitals. The pull-off forces measured by AFM are in accord with the calculated molecular structure but, despite this, the rates of tribochemical decomposition of all the adsorbed carboxylates are identical. However, the carbon is lost from the surface at different rates and this is ascribed to the different reactivities of the resulting carbonaceous species that are tribochemically produced at room temperature, but form thermally at ~ 650 K. This results in lower-energy barrier pathways, such as β-hydride elimination reactions, occurring preferentially compared to higher-activation-energy ones, such as coupling reactions. It is proposed that these rates are influenced by the ability of the terminal groups to access the copper surface and accounts for the relative reaction rates and the amount of carbon deposited onto the surface. [ABSTRACT FROM AUTHOR]

Composition, chemical structure, and dielectric characteristics of boron carbonitride films BCxNy prepared by chemical vapor deposition upon thermal and plasma activation of the initial gas mixture are studied. The dependence of elemental composition, dielectric constant, and resistivity of the films on synthesis conditions (type of the organoboron precursor, synthesis temperature, type and content of the additional gas) are determined by Auger electron spectroscopy and X-ray photoelectron spectroscopy. The dielectric constants of prepared films vary within 3.7-6.3 and their resistivities vary within 1012-1015 Ω·cm. The stability of dielectric properties of BCxNy films during their storage in air is studied for the first time. [ABSTRACT FROM AUTHOR]

Nickel composite coating reinforced with reduced graphene oxide is fabricated by pulse electrodeposition method from a surfactant‐free bath at different current densities. The reduction of graphene oxide is done by an ecofriendly method which uses chlorophyll (CHL) as the reducing agent. The CHL also acts as a stabilizer because of its amphiphilicity. Auger electron spectroscopy is used to study the surface morphology and characteristics of the deposited coatings. Nanoindentation is used to study the mechanical properties. Electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy are used to study the corrosion behavior in 3.5 wt% NaCl solution. The coatings are found to exhibit superior hardness, Young's modulus, and corrosion resistance when compared with the pure Ni coating. Hardness and corrosion resistance are found to improve almost tenfold at optimized condition. Scanning electron microscopy of the corroded surface of the coatings provides an insight into the corrosion process. [ABSTRACT FROM AUTHOR]

In the framework of the protection of copper objects exposed to atmospheric corrosion, different solutions are envisaged, among them carboxylate treatments (HC10). In this study, an analytical approach based on complementary techniques from micrometer to nanometer scale (μRS, SEM-EDS, SAM) is used to describe the properties of the corrosion products layer (CPL) and determine the penetration depth of the HC10 protection treatment inside the CPL of copper samples issued from the roof of the Saint Martin church in Metz. The CPL consists in a thick brochantite layer (20 to 50 μm), mainly composed of Cu4SO4(OH)6, on top of a thinner (1 to 5 μm thick) cuprite layer, Cu2O, acting as a natural corrosion barrier on the metal. Application of the organic treatment is implemented by immersing the corroded samples in HC10 solution, consistent with future requirements for large scale applications. Even for short-term duration (one minute), the HC10 treatment penetrates to the cuprite/brochantite interface, but Cu(C10)2 precipitate is only detected locally, whereas for a longer immersion of thirty minutes, it is present in higher proportions in the whole brochantite layer, filling the pores, up to the cuprite/brochantite interface. Cu(C10)2 acts as a second inner barrier and prevents liquid infiltration.

Using the methods of tunneling, infrared, X-ray photoelectron, Auger, and Raman spectroscopies, X-ray diffraction, and transmission electron microscopy, we study the structure and conductive properties of carbon films synthesized on various metal substrates (Al, Mo, Re, Ta, Ag, Cu, and Pt). The effect of the substrate material on the properties of the carbon film is studied. Based on non-empirical quantum-mechanical calculations, an analysis of the experimental vibrational spectra is carried out. The work function of the substrate material is concluded to depend on the length of the chain fragment. [ABSTRACT FROM AUTHOR]

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The relationship between the properties and substrates of graphene is important to research the graphene synthesized by a bottom-up approach. Here, we synthesized graphene with a surface segregation method and demonstrated that a quadrilateral graphene was formed by using Ni(110) as a substrate. Most of the graphene edges were parallel to the [101] or [100] directions of Ni(110). We found that sulfur impurities in Ni that segregated to the surface with a C(2 × 2) surface reconstruction during the graphene growth played critical roles in the formation of the quadrilateral graphene flakes. Image 1 [ABSTRACT FROM AUTHOR]

Abstract: The distribution of copper, carbon, and oxygen in the surface layers of steel 30KhGSN2A plates after the implantation of copper ions from a pulsed ion source with an accelerating voltage of 30 kV in a vacuum chamber with a residual gas pressure of 8 × 10-4 Pa is studied by Auger spectroscopy. The depth profile of copper in the surface layer has a maximum at a distance of ~90 nm from the plate surface. This profile is close to the depth distribution of implanted copper atoms in 30KhGSN2A steel under the same conditions that was simulated by the Monte Carlo method. The difference between the experimental and calculated profiles is caused by the fact that a 50-nm-thick carbon layer forms on the steel surface during implantation. In the revealed intermediate layer (50-120 nm), iron is partly in the oxidized state. Possible mechanisms of the influence of the structure of the surface layers that form during copper implantation into steel 30KhGSN2A plates on their tribological properties are considered. [ABSTRACT FROM AUTHOR]

Auger spectroscopy has not found widespread application in the geological sciences, largely because specimens are often non-conductors that charge under electron beams. However, it has proven to be useful for the characterization of sub-micrometer mineral grains in certain meteorites, where sample charging issues can be mitigated. We describe the development of analytical protocols for the measurement of presolar silicate grains using Auger spectroscopy and review how this technique has helped our understanding of the stellar origin and subsequent evolution of these grains. [ABSTRACT FROM PUBLISHER]

Thin films of CrN were synthesized in a DC magnetron sputtering system using a mixture of Ar + N 2 . The chemical composition and bonding configuration were examined using X-ray photoelectron spectroscopy (XPS) revealing Cr N bonds. The stoichiometry variation dependence on the N 2 flow was also analyzed using Auger spectroscopy. Both, The XPS and Auger analyses were performed in situ. A gradual increase was observed in the nitrogen concentration in the coatings as the N 2 was increased into the reaction chamber. The electrical behavior was studied while varying the N 2 concentration. A lower resistivity was observed as the nitrogen concentration was increased into the sample before reaching the stoichiometric concentration; however, the resistivity increased at higher nitrogen concentrations (overstoichiometric coatings). Considering that chromium is a magnetic material, a slope change in the resistivity was observed around the Néel temperature. Furthermore, the obtained Hall coefficient showed changes in the carrier type (negative or positive) depending on the nitrogen concentration of the CrN coatings. [ABSTRACT FROM AUTHOR]

Size-selected Ag n -clusters on unsupported graphene of a commercial Quantifoil sample have been investigated by surface and element-specific techniques such as transmission electron microscopy (TEM), spatially-resolved inner-shell X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). An agglomeration of the highly mobile clusters into nm-sized Ag-nanodots of 2–3 nm is observed. Moreover, crystalline as well as non-periodic fivefold symmetric structures of the Ag-nanoparticles are evident by high-resolution TEM. Using a lognormal size-distribution as revealed by TEM, the measured positive binding energy shift of the air-exposed Ag-nanodots can be explained by the size-dependent dynamical liquid-drop model. [ABSTRACT FROM AUTHOR]

Ultrathin carbon films were grown on different types of metallic substrates. Free-standing foils of Cu and Ni were prepared by electroforming, and a pure Ni film was obtained by galvanic displacement on a Si wafer. Commercial foil of Ni 99.95% was used as a reference substrate. Carbon films were grown on these substrates by chemical vapour deposition in a CH4-H2 atmosphere. Obtained films were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy, and ultraviolet photoemission spectroscopy. The XPS at grazing collection angle was used to determine the thickness of carbon films. Depending on the deposition parameters, the films of graphene or graphite were obtained on the different substrates. The uniformity of graphene and its distribution over the sample area were investigated from Raman data, optical images, and XPS chemical maps. The presence of graphene or graphite in the films was determined from the Raman spectra and Auger peak of C KVV. For this purpose, the D parameter, which is a fingerprint of carbon allotropes, was determined from C KVV spectra acquired by using X-rays and electron beam. A formation of an intermediate layer of metal hydroxide was revealed in the samples with graphene overlayer. [ABSTRACT FROM AUTHOR]

We investigated properties involved in the enhancement in electrocatalytic carbon dioxide (CO 2 ) reduction to carbon monoxide (CO) in electrochemically treated Ag surfaces with surface sensitive analysis methods such as Auger spectroscopy, atomic force microscopy (AFM) coupled with Kelvin probe force microscopy (KPFM) techniques, and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The absence of Ag M 4,5 VV Auger signals for the electrochemically treated Ag indicate the presence of localized surface oxygen (O) which survives on the best performing Ag electrocatalysts even in the reductive environment of the CO 2 reduction reaction. Higher work functions were located at the nanostructure boundaries observed by KPFM/AFM implying the higher surface O concentrations in these regions. Furthermore, NEXAFS measured the selective prominence of π * states over σ * in the active Ag surfaces which suggests stronger interaction with intermediates of CO 2 reduction while minimizing the –OH interaction contributing to increase CO 2 reduction activity and selectivity. These results provide direction in engineering surfaces for efficient electrochemical CO 2 conversion. [ABSTRACT FROM AUTHOR]

The present work continues the analysis of results of Dementjev et al. (2015) in order to identify the interlayer interactions of the π-bands. Analysis of the N(E) C KVV Auger spectra of highly-ordered pyro-graphite showed the absence of the electron exchange between the π-bands in 1–6 layers. Since the π-bands are formed by the p z → π transitions, one can suggest that the π-band occupation at each graphene layer is formed by the p z -electrons of this layer. Since the p z electrons belong to the σ p -bands, the p z → π transitions in the σ p -bands in each of 2–6 graphene layers result in formation of holes H, whose concentration is equal to the concentration of electrons in the π-bands [H i ] [π i ]. This shows the origin of the ambipolar conductivity in graphene. The absence of the electronic interaction between the π-bands allows a suggestion that the interaction between top six graphene layers is due to the van der Waals electrostatic attractive forces. These forces promote the p z → π transitions in each of the 2–6 graphene layers and depend on the number of graphene layers above. The N(E) C KVV Auger spectra allow identification of number (1–6) of graphene layers and the π-band occupation at each of the layer. For the first time a specification of the van der Waals forces in HOPG was done. [ABSTRACT FROM AUTHOR]

In this paper, ZnO nanocrystals were synthesized using a simple micro-droplets technique from a solution prepared by dissolving zinc acetate di-hydrate [Zn(CH 3 COO) 2 , 2H 2 O] in methanol. Microdroplets were deposited on glass substrates heated at 100 °C, the obtained samples of ZnO films were investigated by XRD, AES, AFM, ellipsometry and PL. XRD patterns reveal the wurtzite structure of ZnO where the lattice parameters a and c , calculated from XRD signals, show a nanometric character of ZnO nanoparticles. The chemical composition of ZnO film surfaces was verified by Auger electron spectroscopy (AES). From Auger signals, oxygen (O-KLL) and zinc (Zn-LMM) Auger transitions indicate well the presence of Zn-O bonding. The surface topography of the samples was measured by atomic force microscopy (AFM) where ZnO nanoparticles of average size ranging between 20 and 80 nm were determined. Some optical properties as dielectric constants, refractive index, extinction coefficient as well as the optical band gap were determined from ellipsometry analysis. The dispersion of the refractive index was discussed in terms of both Cauchy parameters and Wemple & Di-Dominico single oscillator model. The photoluminescence (PL) measurements exhibited two emission peaks. The first at 338 nm, corresponding to the band gap of ZnO, is due to excitonic emission while the second around 400 nm, is attributed to the single ionized oxygen vacancies. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the influence of temperature on the nickel grain boundary equilibrium segregation of sulfur and the resulting intergranular fracturing susceptibility. Auger electron spectroscopy has been used to study equilibrium segregation of sulfur to the grain boundaries of a metallic nickel, with a mass bulk content of 3.6ppm in sulfur. Samples were first annealed at adequate temperatures for sufficiently large equilibrium time, and then quenched in water at room temperature. The analysis carried out shows a significant increase of sulfur concentration in the grain boundary with decreasing temperature. However, the sulfur content in the grain boundary shows a drastic shrink at 700C. This can be interpreted by the formation of an aggregate sulfide compound in the area of the grain boundaries. At 650C, in situ brittle fracture becomes unworkable and only intragranular fractures are observed. Using the results obtained through the investigation of the grain boundaries by Auger spectroscopy, the standard segregation energy is estimated as . [ABSTRACT FROM AUTHOR]

Results of the investigation of multicomponent coating deposition on the metal substrate in the cathode part of a dense plasma focus device are presented. The features of the processes accompanying the coating are considered: evaporation of elements of chromium-manganese austenite 25Cr12Mn20W tube, which was located along the axis of the plasma focus PF-1000 chamber, under high temperature dense deuterium plasma and deposition of the elements on the model material in form of a copper arc. It is shown that, in the realized exposure mode (the power density of the plasma flow q = 10-10 W/cm in the zone of its impact on the tube and q = 10 W/cm in the region of interaction of the plasma with the copper substrate), the proposed method makes it possible to obtain a coating of submicron thickness on the substrate surface, which includes the evaporated elements of the steel tube. The combined action of powerful streams of fast deuterons and hot plasma in the central part of the copper arc was examined. The structural state, elemental composition, mechanical characteristics, and possible mechanisms for hardening of the deposited film coating are discussed. [ABSTRACT FROM AUTHOR]

AlN-SiC-YAlO composite materials with a high absorption of microwave frequency (27-65 dB/cm) produced by pressureless sintering of mixtures consisting of AlN(2H), YO, and SiC (6H) in 46, 4, 50 wt %, respectively, have been studied. The SiC components of the mixtures were used in sizes of 1, 5, and 50 μm. It has been shown that the resistivity of the developed materials depends essentially on the materials structures: sizes of SiC inclusions, distances between them, and state of the interfaces. It has been found that the increase of the SiC inclusions sizes in the material structure from 3 to 7 μm results in the decrease of the resistivity from 10 to 90 Ω·m, and at the decrease of the SiC inclusions sizes from 3 to 0.5 μm there forms a SiC uninterrupted skeleton, which also decreases the resistivity to 210 Ω·m. Thus, composite materials that contain 50 wt % SiC (inclusions sizes of 3 μm) are the most efficient in producing absorbers of microwave radiation. Interlayers of yttrium aluminum garnet, which are located at the SiC grains boundaries, prevent the forming of AlN(2H)-SiC(6H) solid solutions and thus, make it possible to keep high dielectric characteristics of a composite material based on aluminum nitride and afford a high absorption of a microwave radiation. [ABSTRACT FROM AUTHOR]

We discuss application of the Auger parameter and Wagner plot concepts to the study of small copper clusters deposited on various supports such as C(graphite), SiO 2 and Al 2 O 3 . We demonstrate that the cluster size and the electronic properties of the support influence the shifts of both the binding energy of the Cu 2p 3/2 transition and the kinetic energy of the Cu L 3 M 45 M 45 ; 1 G Auger transition. We find that the Cu L 3 M 45 M 45 ; 1 G-2p 3/2 Auger parameter and Wagner plot allow one to single out and measure both initial- and final-state effects with a detail which is superior to that achieved in photoemission studies. [ABSTRACT FROM AUTHOR]