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We present the results of studies of the phase composition of an oxide layer formed on the surface of U8 and U10 carbon tool steels after laser treatment in air using a quasi-continuous laser source. Data on the structure of the oxide–metal interfaces are obtained by X-ray photoelectron spectroscopy using the AlKα1,2 line; the SPECS surface analysis system is applied. The thickness of the completely oxidized surface layers is 38.7 and 99.0 nm, respectively, for steels U8 and U10. The thickness of the transition layer (81.0 nm) located at the interface with unmodified bulk steel and consisting of iron oxide FeO and iron atoms for U10 steel is approximately two times smaller than that for U8 steel. We determine the composition of the oxides on the surface of the steels after laser processing. The surface of U8 steel is mainly a wustite film, the presence of which determines the poor wear characteristics of the surface of the laser-action zone. On the contrary, the thicker oxide layer of modified U10 steel containing Fe2O3 and Fe3O4 with better strength characteristics ensures a higher wear resistance of the U10 steel surface after laser processing during tribological tests. For U10 steel, the wear rate of the modified surface is more than halved, while for U8 steel, this figure is only ~17%.

Nitrogen-doped carbon materials were prepared by the pyrolysis of carbon black Vulcan XC-72 impregnated with nitrogen-containing Pd (II) and Ni (II) complexes. The composition of materials was studied at different stages of their synthesis. It is shown that nanoparticles of metals and/or their oxides are not the main electroactive component of materials in the oxygen electroreduction reaction (ORR). It is established that the palladium complex provides a much more efficient doping of carbon with nitrogen compared to the nickel complex of a similar composition. This results in the high ORR electrocatalytic activity of the catalyst obtained, palladium complex being used in an alkaline medium. This material is a promising one to be used as an electrocatalyst in fuel cells with an anion-conducting membrane.

In this paper, we present the study results of the surface layers of carbon steels U8 and U10 performed by X-ray photoelectron spectroscopy after laser exposure. The thicknesses of oxidized surface layers were determined to be 43 nm and 108 nm for U8 and U10 steels, respectively. Both the total thickness of the formed oxide film and its phase composition (FeO, Fe2O3, Fe3O4) with depth were found to change depending on the concentration of iron, oxygen, and carbon atoms in the considered steels. The “layer” structure effect of the oxides of the layer modified by laser irradiation on the frictional characteristics of steels is shown. In particular, the presence of FeO oxide on the U8 steel surface increases the wear characteristics, while the presence of Fe2O3 and Fe3O4 oxides provides a higher wear resistance of steel U10 compared to an unirradiated steel surface.

In a condensed matter system, phonons and plasmons are well-known quasiparticles that represent unusual dispersion behavior of energy and momentum at nanoscales. In a nanoscale Mo/Si multilayer str...

The deactivation rate of Co-Al2O3/SiO2 Fischer–Tropsch synthesis catalyst have been experimentally assessed at industrially relevant conditions (T 198–237 °C, P = 60 bar, H2/CO = 1.85, GHSV 2000–7000 h–1). The fresh and spent catalyst was characterized by XRD, XPS, BET, TEM, and SEM–EDX techniques. Decreasing active surface area due to cobalt oxidation by product water and sintering of cobalt crystallites were found to be minor factors for the deactivation. The principal reason of activity loss seems is diffusion limitations arising due to catalyst pores plugging by product wax. The linear dependence between gas flow rate and estimated catalyst lifetime was revealed. High GHSV of fresh synthesis gas and/or high circulation ratio of product gas should be employed to prevent rapid loss of catalyst activity.

The phonon and plasmon excitations and electronic properties of interfaces of periodic W/Si and Si/W multilayer structures were investigated. The Boson band originated from quasilocal surface acoustic phonons for ultrathin Si layers, excited by Raman scattering. In confined Si layers, a small fraction of crystalline Si nanoclusters were embedded within a large volume fraction of amorphous Si (a-Si) nanoclusters. The size of the a-Si nanoclusters was smaller for the thinner Si layer in the periodic layers. The plasmon energy in the Si layer was blueshifted with a decrease in the thickness of this layer. This was explained by the size-dependent quantization of plasmon shift. The valence band spectra comprised a substantial fine structure, which is associated with the interaction of valence orbitals of the W and Si atoms at the interface boundaries. For thinner Si layers, the binding interaction of W5d and Si3p states leads to the splitting of the density of states near the Fermi level in the energy range of 1.5–5 eV. However, the energy splitting with two maxima was observed at 0.7 and 2.4 eV for thicker layers. Thus, the results of X-ray photoelectron spectroscopy have indicated that the interface of W/Si multilayers consists of metal-enriched tungsten silicide. Both the atomic structure and the elemental composition of the silicide were modified with a change in the thickness of the Si layers. This novel investigation could be essential for designing nanomirrors with higher reflectivity.

The use of oxygen-doped semi-insulating silicon films of the SIPOS type as passivation coatings for semiconductor devices and IC makes it possible to increase the breakdown voltage of highvoltage devices. The aim of this work is to establish the influence of the oxygen content on the phase composition of SIPOS films and their electrophysical properties. The results of comprehensive studies show that SIPOS films at different values of γ have a complex phase composition of nanocomposites based on amorphous silicon containing silicon nanocrystals and silicon suboxides with a low oxidation state, such as SiO0.47, while SiO2 dioxide is not formed even at large values of γ.

The influence of relative content of a metal component on the phase composition and substructure of Cox(MgF2)100 – x in a wide range of x = 16–63 at % is studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and infrared (IR) spectroscopy. The layers of nanocomposite with a micron thickness have been obtained by the ion-beam sputtering of the target in the argon environment. The results reveal that the relative metal cobalt content in the MgF2 dielectric matrix strongly affects the phase composition and substructure of nanocomposites. With a lower content of cobalt, it is in the amorphous state in the form of clusters in the MgF2 nanocrystalline matrix. An increase of cobalt content to x = 29 at % on a sitall substrate and to x = 42 at % on a glass substrate in the X-ray amorphous MgF2 dielectric matrix leads to the formation of cobalt nanocrystals with a hexagonal crystallographic system, whose sizes are on the order of 10 nm. These are predominately oriented in the basis plane of the (001) hexagonal lattice of α-Со. A further increase of cobalt content to c = 59 at % enlarges the α-Со nanocrystals to ~20 nm with retaining the same orientation. In accordance with a fine structure analysis of XPS spectra of Со 2p and О 1s, cobalt is strongly oxidized on the surface of all the composites; only on the surface of samples with a low content of Co is X‑ray amorphous cobalt found in a metallic state along with cobalt oxide. The IR spectra of these samples with the lowest metal phase content exhibit the pronounced modes from the nanocrystalline MgF2 dielectric phase.

The polycrystal multiferroic samples of BaFe2/3W1/3O3 (BFWO) and SrFe2/3W1/3O3 (SFWO) are synthesized by solid solution reaction route followed by sintering. The samples are analyzed using the methods of X-ray diffraction (XRD), dielectric, Mossbauer and X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometry (VSM). The XRD study reveals that BFWO possesses two crystal phases: cubic and hexagonal. SFWO is a single phase with a tetragonal symmetry. The VSM and Mossbauer spectroscopy show that both materials are ferrimagnets with magnetic phase transition temperatures TM ≈ 300 K for BFWO and TM ≈ 400 K for SFWO. The iron ions are in Fe3+ state. The XPS studies reveal the presence of the oxygen vacancies in the BFWO and SFWO samples which are responsible for the appearance of the tungsten ions with intermediate valences. BFWO is found to be paraelectric at room temperature. In the SFWO sample the phase transition from tetragonal (ferroelectric) to cubic (paraelectric) phase occurs in the range of 420

Thickness-dependent shift of energy position and fine structure of the collective oscillation of electron gas (plasmons) in the upper layer of silicon (Si) and tungsten (W) in the W/Si and Si/W multilayer mirrors was studied by X-ray photoelectron spectroscopy, respectively. In the spectra, doublet energy components of plasmon excitation were observed, which belong from the Si/vacuum or W/vacuum, and W/Si or Si/W interfaces. The plasmon excitation energy depended on the thickness of the Si and W layers in the multilayers. The intensity of the plasmon component along with the Si/vacuum or W/vacuum interfaces was increased with increasing the thicknesses of Si (or W). However, the intensity was declined along with the W/Si (or Si/W) interfaces. The fine structure of the plasmon was explained by proposing the framework of the electron scattering model in a thin film with the consideration of a semi-infinite solid. The contribution of surface and volume plasmons excitation to the reflectivity of the multilayer mirrors was described. The reflectivity of mirrors was higher for the lower value of plasmons excitation intensity.

The paper takes a new look at studying the phase composition and structure of oxide films of the T8 tool induced by Nd: YAG laser radiation in air. It was decided that the best method for this investigation is the XPS method combined with ion depth profiling of the T8 tool steel sample by the SPECS Surface Analysis System. The maximum thickness of the oxidized FeO surface layer is 126 nm; the thicknesses of WO 3 , V 2O 5 , and V 2O 3 oxide layers of the alloying elements of T8 steel are 97 nm, 90 nm, and 126 nm, respectively. We have provided further evidence that pulsed laser radiation contributes to selective enrichment of the steel surface with W and Mo alloying elements, whose maximum is located at a depth of 90 nm. The segregation theory of Guttman ternary systems was employed to prove that the enrichment of the T8 steel surface layer is influenced by oxidative processes occurring during laser irradiation in air. In addition, we surveyed the impact of the phase composition of T8 surface oxides on their tribological properties under environmental conditions.

The temperatures of the ferroelectric phase transition in the bulk and in the near-surface part of PbSc 1/2 Nb 1/2 O 3 (PSN) single crystal were determined from the temperature dependence of dielectric permittivity measured at several frequencies. These temperatures differ by 12 K due to different degree of Sc and Nb ordering. X-ray photoelectron spectra of the Pb4f-, Pb5d-, Nb3d-, Sc2p-, O1s energy levels and valence band of PSN single crystal were studied by X-ray photoelectron microprobe ESCALAB 250 at several temperatures. Total and partial densities of electron states of PSN in the paraelectric and ferroelectric phases were calculated via the method of self-consistent full multiple photoelectron scattering in the real space, using the Feff9 code. Calculations have shown an increase in the intensity of Pb6s peak as a result of transition from ferroelectric to paraelectric state. The present calculation and the experiment have shown the absence of the energy shift of Pb6s states during the ferroelectric–paraelectric phase transition. Comparison of calculated and experimental results shows a close correspondence between them.

Improving the tribological properties of mineral oils is necessary for energy conservation and enhancing machine efficiency. The antifriction and antiwear properties of 10W40 oil were significantly improved by the addition of small amounts of oxidized graphite flakes. According to the X-ray photoelectron spectroscopy (XPS), this improvement was related to the oxidation of ultrasonicated graphite flakes in an ambient atmosphere accompanied by the adsorption of oxygenated compounds. The oxidation induces the defects which modify the chemical structure in an sp 2 graphite lattice. The dispersion stability of graphite flakes increased in 10W40 oil due to their structural defects and adsorbed oxygen functional groups. This was found to be the main reason behind the improvement of the lubricating properties of graphite flake additives. The formation of transfer films of the graphite structure on the sliding interfaces was shown by the micro-Raman spectroscopy, which explained the improvement of the antifriction and antiwear properties of the mixture by the mechanical reasons.

The influence of relative content of the metal component on the phase composition and substructure of (CoFeZr)x(MgF2)100−x film nanocomposites between x = 7÷51 (at%) has been established by X-ray diffraction (XRD), X-ray electron spectroscopy (XPS) and infrared spectroscopy (IR). Ion-beam sputtering of a composite target from Co45Fe45Zr10 amorphous alloy plate with MgF2 dielectric inserts allow prepared micron-thick nanocomposite layers in the argon atmosphere. The results show that at a relatively low content х 25, the MgF2 matrix becomes X-ray amorphous, and CoFeZr alloy nanocrystals of the hexagonal syngony based on the α-Co structure with dimensions of about 10 nm are first formed; they are predominantly oriented in the plane of the hexagonal lattice (001). With a further increase of the metal alloy content up to х~40 in the region nearer to the percolation threshold, the crystal structure of nanocrystals of the CoFeZr alloy becomes a cubic phase based on α-Fe with a preferred orientation of (110). XPS studies confirm the presence of a predominant type of metal bonds in clusters and nanocrystals of CoFeZr, despite the oxidation of the thinnest surface layers, as well as ionic bonds in the MgF2 dielectric matrix, preserved because of self-organization even in non-equilibrium conditions of ion-plasma sputtering. Two features on the curve of the dependence of the resistivity of nanocomposites on the alloy concentration are due to: the first one (x~25) - the formation of nanocrystals of hexagonal symmetry from clusters of the amorphous CoFeZr alloy, and the second one (x~40) nearer the percolation threshold - coincides with the phase transition of nanocrystals from hexagonal to cubic structure.

Valence band and core level X-ray photoelectron spectra (XPS) are measured in single-crystal solid solutions Pb 1- x Ba x TiO 3 ( x = 0, 0.021, 0.146, 0.24, 0.541, 0.784, 0.906, 1). Valence band densities of states (DOS) and theoretical valence band XPS are calculated for Pb 1- x Ba x TiO 3 ( x = 0, 0.12, 0.25, 0.5, 0.875, 1) via the method of multiple electron scattering in real space. Experimental and theoretical valence band XPS are in good agreement. The increase of ionicity of the Ti O bonds in Pb 1- x Ba x TiO 3 upon the growth of relative Ba content x is predicted theoretically and shown experimentally using the energy position of the charge transfer satellites in the Ti2p XPS. The increase of Ti2p-spectrum line widths against relative Ba content x is observed.

The samples of the tool steel P6M5 were modified by means of laser irradiation (hereinafter - LO). The chemical composition of the sample surface before and after the LO was studied using the Auger and X-ray photoelectron spectroscopy (hereinafter - AES and XPS respectively). It was found that while the steel is exposed to LO, the thick oxide layer consisting mainly of the Fe2O3 oxide is formed. It was established that the modification with LO leads to increasing of wear resistance and durability of the R6M5 steel because of a double reduction of the friction coefficient.

An integrated study of samples of Bi1−хCaхFeO3-δ (BCFO) system for 0 ≤ x ≤ 1 (step 0.1) is performed using X-ray diffraction (XRD), Raman scattering, Mossbauer spectroscopy, and X-ray photoelectron spectroscopy (XPS). Measured elemental compositions of samples were found to deviate substantially from nominal ones. X-ray structure analysis discovered a continuous series of solid solutions with perovskite structure (or its derivatives) on the interval of nominal Ca content 0 ≤ x ≤ 0.9. However, the analysis of the data from all the methods used, limits the region of single phase samples (in presence of insignificant amount of foreign ones) to nominal Ca content interval 0.1

The alternate bi- and tri- layers nanoscale periodic multilayers of Mo/Si, Mo/Be and Mo/Be/Si are useful for the high reflectivity mirrors, operating effectively around 13.5 nm of wavelength. In X-ray photoelectron spectroscopy (XPS), binding energy shift of BeO was observed in the Mo/Be structures. However, the chemical shifts of BeO and SiO2 was observed in the Mo/Be/Si multilayer structures. These evidences have indicated the near surface oxidation of multilayers. In the spatially confined layers, the plasmon was excited by the inelastic scattering of Mo4p photoelectrons, generated by the AlKα X-ray radiation of XPS. In the periodic multilayers, the plasmon was excited at higher energy as compared to the bulk counterpart, which was associated to quantum confinement of the condensed Si and Be nanolayers. In the bi- and tri- layers, the quantum confinement of plasmon in the Si nanolayer was fundamentally described by the density of valence electron and energy width of the band gap. However, in the bi- layer of Mo/Be, the plasmon shift of metallic Be layer was associated to confinement of the conduction electron density.

The practice of applying the methods for determining the relative contents of carbon atoms in sp2 and sp3 hybridization states from the profiles of C1s X-ray photoelectron and carbon KVV (CKVV) Auger spectra is analyzed. Difficulties in using C1s and CKVV spectra for determining the sp2/sp3 ratios are discussed. A method is proposed for evaluating the fractions of sp2 and sp3 phases based on the fitting of the valence band X-ray photoelectron spectra by superposition of valence band spectra of samples with carbon atoms in pure sp2 and sp3 states. Relative fractions of sp2 and sp3 phases on the virgin surfaces of two ultrananocrystalline diamond films, and on their surfaces subjected to friction, were determined using C1s spectra, CKVV Auger spectra, and valence band spectra. All three methods gave the results that are consistent for virgin film surfaces with accuracy of 2%, and for the surfaces of films subjected to friction, 15%. In contrast to the ultrananocrystalline films, three XPS-based methods applied to a microcrystalline diamond film yielded significantly different sp2/sp3 ratios. The reasons for this discrepancy are shown to lie in different analysis depths of these methods, and in different morphology of the film surfaces.

The HoFeO3 and HoFe0.8Sc0.2O3 nanoparticle samples were prepared by the solution combustion method using a mixture of fuels as carbamide and glucose. Their structural, electronic and magnetic properties are studied. The XRD study confirmed that the samples were single-phased and had Pbnm orthorhombic structure. The partial substitutions of Fe3+ ions by the Sc3+ ions with larger ionic radii resulted in the growth of lattice parameters. The surface morphology of the samples was examined by the scanning electron microscopy. The XPS data confirmed that both iron and scandium in the samples are trivalent. However, holmium was found to be trivalent only in the sample with a nominal composition HoFeO3. The data processing for the sample with a nominal composition of HoFe0.8Sc0.2O3 indicated that holmium ions were in Ho2+ and Ho3+ states with the ratio of 0.45/0.55. The Mossbauer study showed that iron ions in both samples were in Fe3+ state. About 10% of Fe3+ ions in HoFe0.8Sc0.2O3 were found to be in local environment with the coordination number 4. Collecting Mossbauer spectra in the temperature range of 14–723K allowed estimating magnetic phase transition temperatures (TM) for HoFeO3 and HoFe0.8Sc0.2O3 nanoparticle samples. TM values are 640K for HoFeO3 and 385K for HoFe0.8Sc0.2O3.

A complex study of Pb1-xBaxTiO3 solid solutions (0.00 ≤ x ≤ 1.00) made using conventional ceramic technology have been performed. By the method of X-ray diffraction, a deviation of the concentration dependences of the structural parameters from additivity was established and the degradation of the diffraction peaks in the interval 0.10

The valence state of transition metal ions in the Co1–x Fe x Cr2O4 (x = 0.1, 0.2, 0.5) system has been investigated using X-ray photoelectron and Mossbauer spectroscopy. It has been shown that, in this system, there are Fe2+ and Fe3+ ions. The relative Fe3+/Fe2+ contents have been determined by fitting the experimental Fe 2p photoelectron spectra by a superposition of theoretical spectra of the Fe2+ and Fe3+ ions, as well as using Mossbauer spectroscopy.

An interpretation of the components of the fine structure of X-ray photoelectron Ni \({2_{{p_{3/1,1/2}}}}\) spectra of Ni1–xCoxCr2O4 solid solutions (x = 0.8, 0.5, 0.3, 0.02, 0.01, 0.005, 0.0) is given. It is shown that the A and B components of the fine structure in Ni \({2_{{p_{3/2}}}}\) spectra originate from the Ni2+ ions located in the octahedral and tetrahedral environments, respectively. The fraction of Ni2+ ions that occupy octahedral positions in ceramics of different composition is determined.

La 1− x Ca x MnO 3 ( x = 0.5, 0.7, 0.85, 0.95) ceramic samples are synthesized by solid state reaction method. Mn3s and Mn2p X-ray photoelectron spectra (XPS) of La 1− x Ca x MnO 3 , and Fe3s-spectra of Bi 1− x Sr x FeO 3 (0 ≤ x ≤ 1) are measured at room temperature. Both Mn 3+ and Mn 4+ ions are discovered in La 1− x Ca x MnO 3 similarly to the case of Fe 3+ and Fe 4+ found earlier in Bi 1− x Sr x FeO 3 ceramics. Relative Mn 3+ /Mn 4+ contents are determined by fitting measured Mn2p spectra with combinations of Mn2p spectra of compounds containing tri- and quadrivalent Mn ions. Relative portion of Mn 4+ is shown to increase with the increase of x . Fe3s spectrum splitting in Bi 1− x Sr x FeO 3 increases with x in contrast to the Mn3s-spectrum splitting in La 1−x Ca x MnO 3 and La 1− x Sr x MnO 3 . Anomalous behavior of Fe3s splitting is explained in the frame of the model of partly itinerant 3d-electrons by strong effect of 3d electron delocalization on electron correlation interaction in final state of 3s photoabsorption.

Load dependent friction behavior of crystalline graphite was studied under ambient atmospheric condition. Structural disorder in the wear track of graphite is increased with load as investigated by micro-Raman spectroscopy. At low loading range, the chemical structure of graphite does not change much and structure remains in 3D graphite phase although there is increase in friction coefficient. This is explained by increase in wear dimension which is directly related to frictional energy. However, wear dimension remains unchanged at high loading range but friction coefficient consistently increases. This is related to transformation of 3D graphite into 2D structure at high loading ranges which consists of highly disordered state of lattice resulting increase in friction coefficient.

Room-temperature Cr2p X-ray photoelectron spectra of samples of the La1–x Sr x CrO3 system with x = 0, 0.1, 0.3, and 0.5 are obtained. The profiles of these spectra vary considerably with x. XPS analysis shows that the chromium ions are in a mixed valence state. The introduction of Sr2+ ions into the lattice is compensated for by the mechanism of Cr3+, Cr4+, Cr5+, and Cr6+ ion formation. Decomposition of Cr2p 3/2 spectra into components with profiles corresponding to Cr3+, Cr4+, Cr5+, and Cr6+ ions has shown that the contribution from Cr6+ ions grows along with with x in the Cr2p 3/2 spectra, while the contribution from Cr3+, Cr4+, and Cr5+ ions is reduced at higher x values.

Anisotropic friction behavior in macroscopic scale was observed in boronated graphite. Depending upon sliding speed and normal loads, this value was found to be in the range 0.1–0.35 in the direction of basal plane and becomes high 0.2–0.8 in prismatic face. Grazing-incidence X-ray diffraction analysis shows prominent reflection of (0 0 2) plane at basal and prismatic directions of boronated graphite. However, in both the wear tracks (1 1 0) plane become prominent and this transformation is induced by frictional energy. The structural transformation in wear tracks is supported by micro-Raman analysis which revealed that 3D phase of boronated graphite converted into a disordered 2D lattice structure. Thus, the structural aspect of disorder is similar in both the wear tracks and graphite transfer layers. Therefore, the crystallographic aspect is not adequate to explain anisotropic friction behavior. Results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy shows weak signature of oxygen complexes and functional groups in wear track of basal plane while these species dominate in prismatic direction. Abundance of these functional groups in prismatic plane indicates availability of chemically active sites tends to forming strong bonds between the sliding interfaces which eventually increases friction coefficient.

The paper contains the investigation results on the structure and phase composition of the laser radiation area (LRA) of the U8 and U10 steels over its entire thickness. In the present study, the laser surface hardening of both U8 (ASTM - W1-7) and U10 (ASTM - W1-9) steels in the air was performed by exploiting a quasi - CW fiber laser with a 130 W power and 3 mm/s processing speed. The phase composition of the oxide layer formed as a result of laser treatment (LT) in air, as well as the structure of the oxide-metal interface on the surface of U8 (ASTM–W1-7) and U10 (ASTM–W1-9) carbon tool steels were studied by X-ray photoelectron spectroscopy (XPS). It was established that the thickness of the completely oxidized surface layers for U8 and U10 steels is 38.7 nm and 99 nm, respectively. The composition of the oxides of the steel surface after LT was determined. The presence of a wustite-based film on U8 steel evidences the low wear properties of the LRA surface, while the thicker oxide layer of the modified U10 steel which contains Fe2O3 and Fe3O4 oxides with better strength properties, on the contrary, provides U10 steel surface with higher wear resistance. It was found that the wear rate of U10 steel modified surface decreases by more than two times, while the given value for U8 steel reduces no more than 17%. The paper reports the metallographic examination of the LRA structure. It was shown that the wear-resistant structural components that appeared after laser treatment lead to an increase in the deformation properties of steels. The maximum microhardness value of the LRA is 710 HV0.1 for U8 steel and 750 HV0.1for U10 steel.

The chemical state of ions in different samples of ceramics of the Ba1 − x Sr x TiO3 (x = 0.2) system produced by varying only a single technological parameter (sintering temperature T S) is studied by means of X-ray photoelectron spectroscopy. The X-ray electron spectra of the Ba4d, Sr3d, O1s, and Ti2p levels reveal well-marked fine structures. As expected, the energy position and intensity of the features of this fine structure vary with T S.

Ionic liquid bis(salicylato)borate (BScB) functionalized graphene oxide (GO) was prepared by γ-irradiation for tribological application. Dose dependent friction behavior of ionic liquid functionalized GO and dynamic changes of chemical phases of tribofilm was investigated by depth resolved X-ray photoelectron spectroscopy. Few layers of graphene oxide tribofilm was observed and it was found to be stable in the sliding interfaces. This was the main reason for the improvement of friction behavior of metallic sliding interfaces.

Low friction coefficient of nanocrystalline diamond (NCD) films deposited on steel alloys was observed in high-vacuum at high-temperature (HV HT) tribological conditions. High wear resistance of the film was observed in high-vacuum at room temperature (HV RT) condition. However, high friction and low wear resistance of the films were measured in ambient atmosphere at room temperature (AA RT) conditions and this was associated to the formation of metal-oxide (Fe2O3 and Fe3O4) layer in the sliding interfaces. Micro-Raman spectra of wear tracks of deformed films and ball scars showed the formation of a carbonaceous bulk tribolayer and this was the main reason for the improved frictional properties in the HV HT conditions. Bulk form of such tribolayer was absent on the ball scar in AA RT condition. The Fe2O3 peak was absent in HV HT which could be one of the important reasons for the low friction coefficient in this conditions. A comprehensive analysis of X-ray photoelectron spectroscopy showed limited oxidation of NCD films and the elimination of contaminated surface layer in HV HT condition which was correlated as a major cause for low friction.

Tribological properties of ultrananocrystalline diamond (UNCD) films were investigated in the ambient atmospheric and high-vacuum in the dynamic transition of tribo-atmospheric condition. The UNCD film with trans-polyacetylene (t-PA) phase showed high friction value in the ambient atmospheric condition and this value became significantly less in the transition of atmosphere to high-vacuum. In contrast, thermally annealed similar UNCD film showed ultralow friction value in the ambient atmospheric condition and this value was high in the transition to high-vacuum tribo-condition. The UNCD film with t-PA phase oxidized in the ambient atmospheric tribological condition which was the main reason for high friction. However, intrinsic hydrogen present in the UNCD films passivated the dangling bonds in high-vacuum tribological condition. Chemical passivation of carbon dangling bonds was efficient for thermally annealed UNCD film in the ambient atmosphere and such passivation was restricted in the high-vacuum. Chemical analysis of the wear track was investigated by the Auger X-ray and X-ray photoelectron spectroscopies for revealing the comprehensive friction mechanisms.

Nanocrystalline diamond films with the properties dependent on the composition of the gaseous medium have been prepared using the microwave plasma enhanced chemical vapor deposition (MPECVD) method. A nanocrystalline film formed in the Ar/CH4 plasma is characterized by a high crystallinity factor, a small grain size, a large fraction of sp 2-amorphous carbon, and, consequently, by an increase in the hardness and elastic modulus. The low value of the friction coefficient of this film is associated with the small grain size and large fraction of the sp 2-amorphous carbon boundary phase that ensures an easy sliding. The contact angle of the film is small (hydrophilic properties) in the case when the plasma consists of an Ar/CH4 mixture. It has been shown that the wetting properties of the films are provided by a thin layer of carboxyl and hydroxyl functional groups passivating the dangling bonds at the surface that are responsible for the boundary lubrication mechanism. It has also been found that the friction coefficient of these films is inversely proportional to the contact pressure dependent on the diameter of the sliding counterbody ball.

The valence state of the Mn ions in ceramic samples of the La1−α BiLaβMnLa1−δ OLa3±γ composition (LBMO) has been studied using the X-ray photoelectron spectroscopy. The presence of Mn3+ and Mn4+ ions in these compounds has been shown. The relative content Mn3+/Mn4+ has been determined by means of fitting the experimental Mn 2p spectra by the superposition of theoretical spectra of Mn3+ and Mn4+ ions. The elemental composition of the samples has been determined by the X-ray photoelectron spectroscopy and electron probe microanalysis. It has been established that the relative content of Mn4+ ions correlates with parameter δ, which characterizes the deviation of the actual elemental composition of the La1−α BiLaβMnLa1−δ OLa3±γ ceramics from stoichiometry La1 − xBixMnO3.

Experimental study of microscopic mechanisms of interaction of polymer composite materials and counterbody metal in a friction unit are carried out. Polymer composites were modified by introduction of various additives containing boron, alkali metals, tungsten and others. The analysis of the surface topography of the counterbody material was conducted by using atomic force microscopy. Electron microscopy and X-ray photoelectron spectroscopy were applied for the interpretation of the obtained results. It is shown that by changing the modifying additives in the material matrix and varying friction modes it is possible both to control the composition of the frictional transfer film on the metal counterbody and to change the microrelief of metal.

An integrated study of samples of Bi1−x A x FeO3±y (A = Sr, Ca) systems for 0 ≤ x ≤ 1 (step 0.1) is performed using X-ray diffraction (XRD), Mossbauer spectroscopy (MS), and X-ray photoelectron spectroscopy (XPS). Considerable deviations of actual elemental compositions from nominal ones in the samples of both systems are discovered. Both Fe3+ and Fe4+ ions are found to be present in the samples of the Bi1−x Sr x FeO3±y system with x > 0. No Fe4+ ions are discovered upon substitution of Bi3+ by Ca2+ in Bi1−x Ca x FeO3±y , neither by Mossbauer spectroscopy, nor by XPS. Charge compensation in Bi1−x Ca x FeO3±y takes place mostly via creation of oxygen vacancies.

Single crystals of orthorhombic multiferroics RMn2O5 (R = Y, Bi, Eu, Gd) and of hexagonal YMnO3 are grown from a solution-melt by mass crystallization. Using an ESCALAB 250 microprobe analysis system, the X-ray photoelectron spectra of valence bands of the multiferroics are obtained. The spectra are interpreted by calculations of the electronic structure of compounds that are close in crystalline structure to the multiferroics studied in this work, as well as by the multiplet structure of rare-earth 4f elements.

Ceramic samples of lead ferroniobate (PFN) having a rhombohedral symmetry at room temperature are obtained. Their ferroelectric and magnetic properties in the vicinity of the antiferromagnetic and ferroelectric phase transition temperatures are investigated. The electrophysical parameters of the polarized ceramic are presented. By means of electron-probe microanalysis, the number of inclusions of Fe-containing impurity phases (∼0.2 vol %) is revealed to be several times higher than that in grains of the PFN ceramics. It is suggested that the above could be caused by the magnetic properties of PFN at room temperature.

The composition of the surface and the chemical bonding are studied by X-ray photoelectron spectroscopy (using an ESCALAB 250 instrument) in a BaTiO3 single crystal within the temperature range of T = 296–573 K. The evolution of the surface Ba-O phase is found to be reversible in this temperature range.

The composition of a multicomponent oxide layer formed by laser pulse heating in air is investigated via X-ray photoelectron spectroscopy. Investigations are performed by means of a SPECS surface analysis system using AlK α1, 2-line radiation. The structures of oxide-metal interfaces within the surfaces of 9XC and R6M5 multicomponent steels have been examined.

The composition of an oxide layer formed by pulse heating in air, and the layer of the oxide-metal interface structure on the surface of 9XC and P6M5 multicomponent alloys, were investigated by X-ray photoelectron spectroscopy (XPS) using a SPECS surface analysis system.

The X-ray photoelectron spectra of the inner levels and valence bands of the surfaces of BiFeO3 and Fe2O3 single crystals have been measured using X-ray photoelectron spectroscopy on an ESCALAB 250 X-ray photoelectron microprobe with monochromatization of X-ray radiation of the AlK α line. The ab initio calculations have been performed by the full-potential pseudopotential method in terms of the density functional theory (Quantum-Espresso program package). The band structure and the total and partial densities of states have been calculated for the BiFeO3 and Fe2O3 systems. A comparison of the theoretical and experimental results has demonstrated good agreement between theory and experiment.

The elemental composition of the surfaces of Pd25V75, Pd44V56, and Cr20Ni80 binary alloys and 40Kh13 instrumental steel exposed for a long time in air has been investigated by X-ray photoelectron spectroscopy (SPECS system, monochromatic radiation AlKα line). The composition of the samples was also investigated as a function of the heating temperature. The features of the dependences of the concentrations of the main components of binary metal systems on the sample processing temperature are explained within the segregation theories of ternary systems of highly diluted solutions.

The elemental composition and the nature of the chemical bond at the surface of two vanadium-palladium alloys are studied as functions of the sample warm-up temperature by x-ray photoelectron spectroscopy. The obtained results are explained in the framework of segregation theories for ternary systems of strongly diluted solutions.

Electronic structure of the PbFe1/2Nb1/2O3 single crystal is studied by means of X-ray photoelectron spectroscopy on an ESCALAB 250 system and first principle FEFF9 at temperatures of 296 and 403 K.

The elemental composition and chemical bonding on the surface of samples of R6M5 instrumental steel subjected to successive heating in air at temperatures from 293 to 1273 K and laser irradiation have been investigated by X-ray photoelectron spectroscopy on a SPECS system. The results obtained are explained within the modern theories of segregations in ternary systems of highly diluted solutions.