Low-doped LM2 molybdenum alloy is obtained by the multiple electron-beam melting of Mo with the addition of 0.02 wt

This experimental work briefly describes the technology of multiple electron-beam melting to produce low-alloy molybdenum alloys with other carbide-forming elements and carbon. Two new alloys described here allow deformation by cold rolling down to a thickness of 0.17 mm. When modifying the Golovin–Sims formula, we show that an alloy with fine (30–200 nm) carbides is hardened during cold rolling much more strongly than an alloy, in which only coarse (≥1 μm) carbides are present. The evolution of continuity defects with the deformation during cold rolling is traced.

Graphene layers on semiconducting substrates, modified using covalent and noncovalent chemical functionalization, can be utilized for the fabrication of hybrid structures combining the physical properties of graphene and organic molecules. In this paper the results of investigations of the atomic and electronic structure of ultrathin graphene layers on β-SiC/Si(001) wafers modified using the phenazine dye Neutral Red are presented. Continuous graphene films consisting of several atomic layers are synthesized on β‑SiC/Si(001) wafers using high temperature annealing in ultrahigh vacuum. The synthesized graphene layers were chemically modified in a solution of diazonium salt of the Neutral Red dye under white-light illumination. The results of scanning tunneling microscopy and spectroscopy demonstrate the formation of a composite phenazine–graphene structure with a large energy gap in all surface regions. The molecules can be oriented preferentially parallel and perpendicular to the graphene layers and form locally ordered structures with rectangular and oblique unit cells. The electronic energy spectrum and band gap in different surface areas depend on the local atomic structure and the molecule’s orientation relative to the surface. According to density-functional-theory calculations, the local modifications of the electronic structure and band gap can be related to deformations (compression or extension) of the phenazine dye molecules because of their interaction with the uppermost graphene layer.

The studies of the properties of graphene synthesized on the surface of epitaxial films of cubic single-crystal silicon carbide preliminarily grown on Si(001) wafers have been reviewed. These studies were supported by the Russian Foundation for Basic Research, project no. 17-02-01139. The results of these studies demonstrate that graphene layers synthesized on β-SiC/Si(001) substrates have the atomic structure and electronic properties of a quasi-freestanding graphene sheet. Continuous graphene layers with a preferential direction of nanodomain boundaries, which is determined by the orientation of steps on the initial surface, can be synthesized on vicinal SiC(001) substrates. The possibility of controlled growth of mono-, bi-, and trilayer graphene on β-SiC/Si(001) wafers has been demonstrated. The studies have shown the opening of a transport gap and a high positive magnetoresistance in a parallel magnetic field in an ordered system of graphene nanoribbons on the vicinal SiC(001) surface. It has been shown that the functionalization of graphene with organic compounds changes the electronic properties of graphene on SiC(001), modifying it to a semiconductor with given properties, which allows applications in modern micro- and nanoelectronics.

We study the in-situ growth of a nanocomposite material consisting of a thin CuPcF4 film and multiphase/multidimensional indium nanoparticles, self-organizing on the surface and in the bulk, at various stages of thermal deposition of metal on an organic film under ultrahigh vacuum conditions. The analysis of high-resolution transmission electron microscopy (HR-TEM) images provided valuable information about the evolution of morphology, size, density, and distribution of indium nanoparticles upon indium deposition. These 2D/3D ultra-small nano-objects turned out to have not only body-centered tetragonal (bct) crystal structure, typical for bulk indium, but also unusual face-centered cubic (fcc) one. Using a synchrotron facility, the study of the electronic structure of the hybrid nanocomposite on variable stages of metal deposition was performed by XPS and NEXAFS. Core-level spectra related to the organics indicated reasonably weak chemical interaction of indium with CuPcF4 molecules, which is not the case for a number of metal/organic semiconductor systems, while valence band spectra have shown a considerable change of the material electronic properties. The energy level diagrams, derived from the experiment, can be applied for the creation of new prototypes of metal-organic memory devices.

A study of the formation processes and properties of nanocomposite materials consisting of indium nanoparticles in a thin film of the organic semiconductor copper tetrafluorophthalocyanine (CuPcF4) is presented. The results are obtained by the new setup for dynamic photoelectron spectroscopy, which allows the recording of spectra in a millisecond interval using the ARGUS photoelectron spectrometer and synchrotron radiation (PETRA III/DESY, Germany). The evolution of the core level (CL) spectra: C1s, N1s, and In3d5/2 recorded directly during the deposition of indium onto the CuPcF4 surface under ultrahigh vacuum conditions is traced. The thickness of the indium coating during deposition increased from 0 to 5 nm. In this range of coatings, more than 150 spectra are recorded for each CL with a recording rate of 0.1 s/spectrum. The following is established: the significant diffusion of indium atoms deep into the organic matrix is observed; in fact, no chemical interaction of indium with carbon atoms is found; indium atoms are located in places close to pyrrole nitrogen of the CuPcF4 molecule. Apparently, during the interaction of In atoms and pyrrole nitrogen atoms, a negative charge is transferred from indium to the CuPcF4 molecule. Thus, data on the fast-flowing processes of the formation of organometallic In–CuPcF4 interfaces are obtained.

The peculiarities of the fine structure of Al–Si–Ni aluminum-matrix composite with a low thermal coefficient of linear expansion, mechanically activated with the addition of nanoscale reduced graphene oxide (RGO), is investigated. The structure is studied by X-ray diffraction analysis, scanning, transmission and high-resolution transmission electron microscopy. The presence of quasi-graphene layers on the surface of aluminum and silicon particles is detected and it is shown that this shell protects them from clumping upon mechanical alloying, which significantly increases the manufacturability of the process of mechanical activation and subsequent compaction. Thus, it is possible to obtain composite materials with a homogeneous structure and higher physical properties (the use of RGO instead of electrode graphite reduces the thermal coefficient of linear expansion (TCLE) of the composite by 10%).

The purpose of this work is the synthesis and study of the properties of nanocomposite structures created by noble metal (silver) nanoparticles (NP's), an exciting class of materials with unique properties differ from both bulk and atomic behavior, which are self-organize in a thin organic film of copper phthalocyanine (CuPc). The structure and morphology of this material, depending on the amount of deposited silver, was studied in ultrahigh vacuum using transmission electron microscopy (TEM) and photoelectron spectroscopy (PES). Metallic atoms deposited on the surface of an organic substrate diffuse into the substrate, forming NPs with a narrow size distribution, which correlates with the content of the deposited metal. With the help of high-resolution TEM, the distance between the atomic planes of individual silver nanoparticles was determined and the steady gathering of individual nanoparticles into agglomerates and then into nanocrystals with inter-crystallite boundaries was observed. PES revealed a generally weak interaction between silver NPs and the organic matrix. However, a strong band bending in the organic film at small coatings with metal atoms was observed.

In this work we have fabricated and studied hybrid organic-inorganic nanocomposite system formed by gold nanoparticles self-assembled in organic semiconductor thin film - copper tetrafluorophthalocyanine (CuPcF4). By means of Photoelectron Spectroscopy and Transmission Electron Microscopy (TEM) the evolution of the morphology and electronic structure of the system as a function of nominal gold content have been investigated. The gold atoms, deposited onto the CuPcF4 surface, diffuse into the organic matrix and self-assemble to nanoparticles in a well-defined manner with a narrow size distribution, which depends on the amount of deposited gold. Using High-Resolution TEM, we were able to observe the atomic planes of single gold nanoparticles and their coalescence processes. Photoelectron spectroscopy has not revealed any detectable chemical reaction between gold and organic. However, the strong upward band bending, induced by gold nanoparticles in the organic film, takes place.

The structure and mechanical properties of a two-phase Kh65N33V2FT alloy has been studied after tests at room and high temperatures. The morphology of the main phases, namely, solid solutions of nickel in chromium (α) and chromium in nickel (γ), is changed depending on temperature. The lattice parameters of the main phases have been determined. The main mechanism of deformation for this alloy is shown to be grain-boundary sliding. Bulk and grain-boundary diffusion creep and self-regulating diffusion-viscous flow is possible in the γ phase during high-temperature deformation. The heat resistance of this alloy is restricted to 1000°C because of the formation of a γ-phase percolation cluster.

The evolution of the morphology and the electronic structure of the hybrid organic-inorganic system composed of aluminum nanoparticles (NPs) distributed in an organic semiconductor matrix—copper phthalocyanine (CuPc)—as a function of nominal aluminum content was studied by transmission electron microscopy and by photoemission spectroscopy methods. The aluminum atoms deposited onto the CuPc surface diffuse into the organic matrix and self-assemble to NPs in a well-defined manner with a narrow diameter distribution, which depends on the amount of aluminum that is evaporated onto the CuPc film. We find clear evidence of a charge transfer from Al to CuPc and we have been able to determine the lattice sites where Al ions sit. The finally at high coverage about 64 Å the formation of metallic aluminum overlayer on CuPc thin film takes place.

Materials with a high on-off resistance ratio could become the basis for resistive random-access memory (RRAM).It is assumed that one of RRAM types can be based on hybrid organic-inorganic systems, while particular attention is focused on hybrid systems consisting of metal nanoparticles (NP) embedded in organic matrix (OM).In this investigation we created and studied the hybrid organic-inorganic systems made of metal (Ag) nanoparticles embedded in organic semiconductor material CuPc.The LEED patterns and NEXAFS data demonstrate that the CuPc films deposited on Au(001) substrate are highly ordered and molecular planes lie parallel to the gold surface.The metal atoms were deposited on the outer surface of the organic molecular film and self-assembled into nanoparticles due to surface and bulk diffusion.The properties of nano-composite materials seem to be significantly dependent on the microstructure, i.e. the size, concentration, bulk-and size-distribution of nanoparticles; therefore we have studied by high resolution transmission electron microscopy the evolution of morphology of nano-composite films as a function of nominal metal deposition.The filled and empty electronic states of the hybrid organic-inorganic systems, energy level alignment at interfaces formed between metal nanoparticles and the organic semiconductor CuPc as well as the chemical interaction at the NP/OM interface were studied by UPS, XPS and NEXAFS methods.

The evolution of the morphology and the electronic structure of the hybrid organic-inorganic system composed of gold nanoparticles (NPs) distributed in an organic matrix—copper phthalocyanine (CuPc)—as a function of nominal gold content was studied by transmission electron microscopy and by surface and bulk sensitive spectroscopic methods. The gold atoms deposited onto the CuPc surface diffuse into the organic matrix and self-assemble to NPs. There is no formation of a continuous metallic Au film on top of the CuPc film up to large nominal coverage of about 130 Å considered in the present study. The gold is assembled in well defined NPs with metallic properties.