In this work, we study the magnetization of two types of particles of a composite consisting of polystyrene and multilayer graphene chemically bonded to it, obtained by magnetic separation of the initial composite. For needleshaped particles, a ferromagnetic type of magnetization was observed for the first time, with values of saturation magnetization that are large for graphene. For flat, macroscopic particles of the composite, a superposition of several contributions to the magnetization was observed.

The transition from 'the initial graphite material, consisting of multilayer graphene of macroscopic size, to its oxidized form occurring as films, followed by their thermal reduction in an atmosphere of hydrogen, allows for obtaining submicron galleries of reduced graphene oxide with oxygen-containing groups on the surface. Such hydroxyl and carboxyl groups were used to functionalize the surface of graphene nanosheets with methacrylate groups to twist graphene layers relative to each other during in-situ copolymerization with styrene. In such a composite, mechanical stresses and defects are potential in the graphene nanosheets, which may be the reason for local superconductivity at room temperature. A similar effect was also recorded for photoreduced graphene oxide with a perforated surface as a component of a pol-ystyrene-based composite.

In this work, we study the magnetization of two types of particles of a composite consisting of polystyrene and multilayer graphene chemically bonded to it, obtained by magnetic separation of the initial composite. For needle-shaped particles, a ferromagnetic type of magnetization was observed for the first time, with values of saturation magnetization that are large for graphene. For flat, macroscopic particles of the composite, a superposition of several contributions to the magnetization was observed.

This paper describes the methods and presents the results of the "Troitsk Nu-mass" experiment spectrometer cleanup after the in\ner volume (40 m(3)) and surfaces (160 m(2)) were contaminated by 5.2 GBq of tritium. The Troitsk Nu-mass experiment of the Institute for Nuclear Research of the Russian Academy of Sciences (Moscow) is designed to measure the spectrum of electrons from tritium decays in order to search for hypothetical particles-sterile neutrinos. Due to some equipment failures, the spectrometer internal volume was contaminated with tritium. The contamination made measurements impossible, and the research program stopped. Different methods were used for cleanup: vacuum extraction, hydrogen soaks, and water vapor soaks. As a result of detritiation, the background level of the main detector of the Troitsk Nu-mass spectrometer was reduced approximately by more than ten times, which made it possible to resume work. The results are consistent with the literature data obtained earlier for normal conditions in the air and can be used for detritiation of similar installations.

The use of reduced graphene oxide (r-GO) is a promising way of fabricating organic–inorganic composites with unique electrical and magnetic properties. In our work, polystyrene/r-GO composites were synthesized, in which both the components are linked together by covalent bonds. The r-GO used differs from the graphene obtained from graphite through mechanical exfoliation using the ‘scotch tape’ by presenting many structural defects. Binding in the composite structure between the components was confirmed by infrared spectroscopy. Elemental analysis was carried out by energy dispersive X-ray spectroscopy. Scanning electron microscopy, X-ray diffraction, and Raman spectroscopy were used to monitor the 2D-order in exfoliated r-GO galleries. Using a vibrating-sample magnetometer, we have shown that the composite magnetization loops demonstrate type-II superconductivity up to room temperature due to r-GO flakes. We believe that a strain field in the r-GO flakes covalently binding to a polymeric matrix is responsible for the superconductivity phenomena.

This work presents our study results of the magnetization of multilayer UV-reduced graphene oxide (UV-rGO), polymer matrix (polystyrene), and a conjugated composite based on them. The mesoscopic structure of the composites synthesized in this work was studied by such methods as X-ray diffraction, SEM, as well as NMR-, IR- and Raman spectroscopy. The magnetization of the composites under investigation and their components was measured using a vibrating-sample magnetometer. It has been shown that the UV-reduction process leads to the formation of many submicron holes distributed inside rGO flakes, which can create edge defects, causing possibly magnetic order in the graphite samples under investigation on the mesoscopic level. This article provides an alternative explanation for the ferromagnetic hysteresis loop in UV-rGO on the base of superconductivity type-II.

The temperature and magnetic field dependences of electron spin resonance was investigated for a graphite / polystyrene composite. The obtained value for the g-factor does not depend on temperature and is equal to 2.003, which is close to the value for a free electron for carbon (g = 2.0022-2.0035). This behavior of the g-factor excludes the possibility of an internal magnetic field in the composite.

It has been shown that in multilayer graphene/polystyrene composite, the static magnetization curve looks the same as in a type-II superconductor. The electron spin resonance in the same composite was studied as a function on temperature and magnetic field. The observed g-factor of 2.003 was independent of temperature and was in the range (g = 2.0022-2.0035) characteristic of a free carbon electron. This behavior of the g-factor excludes the appearance of an internal magnetic field in the composite.

Electron spin resonance in a multilayer graphene–polystyrene composite has been studied as dependent on the temperature and magnetic field. The observed g -factor of 2.003 was independent of the temperature and fell in the interval ( g = 2.0022–2.0035) characteristic of the free electron of carbon. This behavior of the g -factor excludes the appearance of internal magnetic field in the composite.

The dependences of the magnetic moment in the graphite-polystyrene composite on the temperature and magnetic field have been studied. It has been shown that the magnetic field dependence of the magnetic moment of graphite particles is characteristic of superconductors in the same temperature interval where a Josephson current-voltage characteristic was previously observed in the same composite.

UV-perforated reduced graphene oxide flakes of large areas, some of them up to 500 µm in diameter, have been produced on polystyrene surface.These flakes were formed during precipitation of UV-reduced graphene oxide composites based on polystyrene from benzene solutions by petroleum ether.Two composites based on polystyrene with molecular weights of 9,000 Da and 45,000 Da were synthesized to compare their conductive properties.Conditions of the formation of planar structures from UV-perforated reduced graphene oxide flakes were varied.So, resistances were compared for composites deposited from solutions with different concentrations and at different temperatures.Very low resistances for some flakes precipitated from 5 wt.% solution of composite of 9,000 Da molecular mass at the room temperature were obtained.The absolute values of measured resistances were found to be 1.5 orders of magnitude lower than resistance of copper.At the same time some, regions of graphene inclusions from 12 wt.%solution of latter polystyrene composite demonstrated even lower resistance, almost 3 orders of magnitude lower than copper resistance.This result is explained by existence of superconducting component in the reduced graphene oxide inclusions.In the case of composites with graphene flakes produced from higher molecular weight polystyrene (45,000 Da) resistance was high and varied from semiconducting values to non-conductive state.

We report on polymer composites with embedded graphene flakes which exhibit a current–voltage characteristic of Josephson type.

Current-voltage characteristics of the Josephson type have been found for a composite based on polystyrene and graphene dioxide of a mesoscopic size incorporated into it.

A nonmonotonic temperature dependence of the critical current in layered crystals of iron-based superconducting Fe(Se0.3Te0.7)(0.82) solid solution has been observed in the direction perpendicular to layers. This behavior is caused by the alternating sign of the superconducting current, which is due to an interaction between the electron spin in Cooper pairs and the magnetic exchange related to the sublattice of interstitial iron atoms. A change in the direction of the applied voltage leads to enhancement of the Josephson current.

The effect of reactor neutron irradiation on the structure of germanium nanocrystals ion-implanted into an amorphous silicon dioxide film was studied using laser Raman scattering, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The sample irradiation with a high dose of fast reactor neutrons resulted in lattice destruction and amorphization of a part of nanocrystals, leaving off a significant part well retained. Thus indicating that this nano-based material may have potential for the fabrication of devices operating under extreme conditions. Radiation defect annealing and full restoration of the nanocrystal structure were observed at 800°C; however, the average size of nanocrystals and their spatial distribution were changed.

It is shown that a supercurrent in disordered polymers placed between superconductor electrodes may be explained by resonant tunneling of Coopers pairs along polymer channels formed due to electrification effect. Polymer film thickness where supercurrent one may to observe depends on superconducting coherence length in superconductor. The more coherence length in superconductor electrode the more is a polymer film thickness where superconductor exists. Shapiro steps induced by microwave (f = 9.3 GHz) radiation correspond to a single Josephson junction.

Spin-spin relaxation of arabinogalactan and its composites with gold and silver nanoparticles in aqueous solutions was studied from the viewpoint of the possible effect of electrification on the mobility of arabinogalactan macromolecules.

The influence of fast neutron irradiation on the structure and spatial distribution of Ge nanocrystals (NC) embedded in an amorphous SiO2 matrix has been studied. The investigation was conducted by means of laser Raman Scattering (RS), High Resolution Transmission Electron Microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). The irradiation of Ge-NC samples by a high dose of fast neutrons lead to a partial destruction of the nanocrystals. Full reconstruction of crystallinity was achieved after annealing the radiation damage at 8000C, which resulted in full restoration of the RS spectrum. HR-TEM images show, however, that the spatial distributions of Ge-NC changed as a result of irradiation and annealing. A sharp decrease in NC distribution towards the SiO2 surface has been observed. This was accompanied by XPS detection of Ge oxides and elemental Ge within both the surface and subsurface region.