Surface structure modification of PAN based carbon fibers under 30 keV C+, N+, N-2(+) and Ar (+) ions irradiation have been experimentally studied. It has been found that the corrugation effect of the fiber surface, which is typical for high-fluence irradiation with noble gases and nitrogen ions, does not manifest itself under irradiation with carbon ions. The dependences of the formation of surface patterns on depth distributions nu(x) of the number of displacements per atom (dpa) are considered. It has been shown that during corrugation the nu decreases monotonically with a maximum at the surface. The cause of corrugation is twinning of fiber-shell crystallites, which is caused by depth-dependent radiation-induced dimensional changes and relaxation of resulting mechanical stresses. The reason for the absence of surface corrugation under C+ irradiation can be the formation of a textureless modified layer.

Trilayer thin-film magnetic structures NiFe/IrMn/NiFe obtained by DC magnetron sputtering in the presence of a constant magnetic field 420 Oe were investigated by ferromagnetic resonance (FMR) technique. The dependences of the exchange bias, misalignment angle between the uniaxial and unidirectional anisotropies, and the FMR linewidth on the thickness of the antiferromagnetic IrMn layer in the range from 2 to 50 nm are compared for samples with hard Ni _40 Fe _60 and soft Ni _75 Fe _25 ferromagnetic layers of the same 10 nm thickness. Using the data of other authors and our previous data for bilayer structures, possible reasons of the observed dependences are discussed.

Nanocomposites are a new type of material that differs from conventional composite materials in the size of the hardening phase. One of the most promising fillers for nanocomposites is carbon nanotubes. The paper studied structural and functional properties of polymer composite materials based on epoxy resins reinforced with carbon nanotubes. Impact resistance at high speed effects of multilayer composites, which are multilayer structures made of glass fabric and basalt fabric impregnated with polymer on the basis of epoxy resins, has been studied.

The variation in the magnetoresistance of a spin-valve sensor during its linear movement in an inhomogeneous field of a magnetic label at different orientations of the magnetic moment of the spin-valve structure is considered. It is shown that the shape of the sensor signal and its value critically depend on the initial orientation of the magnetic moment and the trajectory of the sensor in the field of the magnetic label.

Ferromagnetic resonance (FMR) linewidth (LW) is a tool for studying the high frequency properties of magnetic materials for their application in high-speed devices. Here, we investigate different mechanisms which determine FMR damping in bilayer ferromagnetic/antiferromagnetic (F/AF and AF/F) exchange bias systems. Variations of FMR LW with the thickness and deposition order of the F and AF layers were studied, as well as their correlation with the exchange bias field and roughness of the sample surface. We observed much larger LW in AF/F structures compared with F/AF samples. It was found that neither the exchange bias nor surface/interface roughness in the samples could explain the difference in LW for F/AF and AF/F samples. Instead, the different underlayer microstructure influenced the grainsize, leading to different angular dispersion of magnetization and different internal stray field in F-layers, promoting a different intensity of magnon scattering and FMR damping in F/AF and AF/F samples.

A comparison is made of the ion-induced corrugation of the shell of carbon fibers reinforcing a KUP-VM composite upon high-fluence irradiation with $${\text{N}}_{2}^{ + }$$ and Ar+ ions with an energies of 10 to 30 keV at temperatures ranging from 100 to 600°C. Irradiation with noble gas ions is better for simulation of the neutron irradiation of graphite materials. Irradiation with nitrogen ions is preferable when modifying a carbon fiber surface.

The ion induced modification of the structure and morphology of low-temperature (SU-1300) and high-temperature (SU-2500) glassy carbons after high-fluence (>= 10(18) cm(-2)) irradiation with 30 keV Ar+ ion in the temperature range from 60 to 600 degrees C are presented and discussed. Raman spectra show an amorphized state of surface both for the low and high-temperature glassy carbons at an irradiation temperature below the temperature of the dynamic annealing of radiation damage, determined by the temperature dependence of the ion-induced electron emission yield; a graphite-like structure at 140 <= T <= 350 degrees C for SU-1300 and at 140 <= T <= 250 degrees C for SU-2500; a structure similar to non-irradiated low-temperature glassy carbon at 350 < T <= 600 degrees C and 250 < T <= 600 degrees C for low- and high-temperature glassy carbons, respectively. In both cases, ion irradiation leads to the temperature-dependent changes in the topography of the modified layer. Ion irradiation under conditions of the dynamic annealing of radiation damage leads to a network topography of the nanowalls.

The results of experimental study of the surface nano-and microstructuring of polyacrilonitrile (PAN) based carbon fiber VMN-4 and viscose based carbon cloth TGN-2MK under 30 keV Ar+ irradiation are presented. Scanning electron microscopy shows a strong difference in evolution of ion-induced morphology for these two carbon fiber types. At sufficiently high fluences, a corrugated morphology is formed on the PAN based carbon fiber, while a network of nanowalls is formed on the viscose based carbon fiber. The found differences are associated with a significant effect of the structure of the surface layer of carbon fiber on ion-induced dimensional changes.

The behavior of the surface of carbon fibers based on polyacrylonitrile, which reinforce the KUP-VM composite, upon corrugation under high-fluence irradiation with $${\text{N}}_{2}^{ + }$$ ions with an energy of 15 and 30 keV and a temperature of the irradiated composite in the range from 100°C to 600°C is described and discussed. In contrast to irradiation with ions of noble gases, it is found that the main parameters of the corrugated structure, such as the tilt angles of corrugations and their fractions on the surface of a fiber, are practically independent of the composite temperature. The corrugation periodicity is hundreds of nanometers, as in the case of irradiation with neon and argon ions. In the case of using ion energies of 15 and 30 keV, the tilt angles are 30° and 40°, respectively. The difference between the temperature dependences of the tilt angle of the corrugations and their fraction on the fiber surface and similar dependences in the case of irradiation with noble gas ions is determined by the peculiarities of the dynamic annealing of radiation-induced damage in the fiber shell due to the chemical activity of nitrogen associated with the creation of C–N bonds and a larger proportion of the amorphous component.

The results of the study of morphological changes in the carbon fibers surface of "Kulon" based on PAN fiber and of carbon textile Busofit under irradiation with helium ions with energies of the order of hundreds of electron volts are presented. Scanning electron microscopy showed a significant ion-induced change in the morphology from the smooth fiber surface to a developed surface with the corrugations, nanowalls and whiskers of submicron height.

The results of a comparative experimental study of the structure and morphology of high-temperature glassy carbon of brand SU-2500 after high-fluence (1018 cm–2 and higher) irradiation with 30-keV Ar+ ions in the temperature range of 60–600°С and glassy carbon samples after treatment at temperatures of 850, 1300, 2000, and 2500°С are reported and discussed. The Raman spectra of irradiated glassy carbon SU-2500 show the amorphous state of the surface layer after irradiation at temperatures below that of dynamic annealing of radiation damage, which is determined from the temperature dependence of the ion-induced electron emission yield, a graphite-like state after irradiation at temperatures of 150–250°С, and a structure typical of glassy carbon samples treated at elevated temperatures after irradiation at temperatures in the range of 250 < T ≤ 600°С. Ion irradiation under conditions of the dynamic annealing of radiation damage leads to a сellular topography, i.e., nanowalls connected by nodes. The sizes of the structure cells are about 150 and 300 nm after irradiation at temperatures of 250 and 600°С, respectively.

The temperature dependences of structural and phase transformations in quartz successively implanted by zinc and fluorine during annealing in nitrogen have been studied. Plates were doped with 64 Zn + ions to a dose of 5 × 10 16 cm –2 with an energy of 50 keV and then with 19 F + ions to the same dose but with an energy of 17 keV. After the implantation, individual Zn-containing particles about 100 nm in size were found on the sample surface. These particles decrease in size during annealing (by an order of magnitude after annealing at 800°C). The implantation leads to the formation of radiation-induced point defects and their clusters in the quartz bulk. Radiation-induced defects are gradually annealed during the heat treatment, and the phase of metallic zinc is transformed first to its zinc oxide (ZnO) at 600°C and then to willemite (Zn 2 SiO 4 ) at 800°C.

The formation of a zinc-oxide phase in a SiO 2 film deposited onto n -type Si substrates grown in the (100) orientation using the Czochralski technique, which is a result of implanting 64 Zn + ions at room temperature, an energy of 50 keV, and a dose of 5 × 10 16 cm –2 , and subsequent heat treatment in an oxygen atmosphere at elevated temperatures, is studied. The surface topology is investigated using methods of scanning electron and atomic force microscopy. The optical properties are studied using the method of photoluminescence spectroscopy at 10 K and by measuring the light reflection spectra. After Zn implantation, a ZnO phase is detected in the subsurface layer of the SiO 2 film. After low-temperature annealing in the range of 400–600°С, Zn-containing precipitates with a cross-sectional size of particles of 20–50 nm are found in the sample and on its surface. After annealing at 700–800°C, Zn-containing precipitates of the Zn·ZnO complex are formed in the subsurface layer, and a phase of the ZnO · Zn 2 SiO 4 complex is found after annealing at temperatures of 900–1000°C. The samples obtained at the annealing temperature optimal for the formation of the ZnO phase (about 700°C) are irradiated with 132 Xe 26+ ions with an energy of 167 MeV. The ZnO phase is found to disappear after irradiation at a fluence of 2 × 10 13 cm –2 and a large number of radiation-induced defects giving a characteristic photoluminescence band are formed. With an increase in the Xe fluence to 5 × 10 14 cm –2 , the intensity of this luminescence band increases.

Abstract The results of experimental study of the morphology evolution of carbon fiber VMN-4 based on PAN fiber depending on 30 keV Ar+ irradiation with exponential fluence decrease from center to periphery of ion beam spot on the target are presented and discussed. Scanning electron microscopy show a strong influence of ion fluence on the morphology, expressed by the transformation of nanoscale conical elements in a submicron corrugated structure.

The 64Zn+ and 16O+ ions were implanted in SiO2 film on Si substrate with next parameters: the implant dose was 5.0 × 1016 cm–2, for Zn+ ions the energy was 50 keV and for O+ ions the energy was 16 keV. Than the samples were subjected to isochronally during 1h annealing in N2 atmosphere in temperature range 400–600°C and than in Ar atmosphere in temperature range from 700 up to 1000°C with a step of 100°C. After annealing the samples surface is structured and its roughness increases due to nanoparticle formation in subsurface layer. In as implanted and in annealed samples on its surface and in its body the Zn-contained nanoparticles with a size about 100 nm were formed. These nanoparticles consist presumably from Zn phase after implantation and from ZnO phase after annealing.