РАЗРАБОТКА НИЗКОТЕМПЕРАТУРНЫХ СЕНСОРОВ МАГНИТНОГО ПОЛЯ НА ОСНОВЕ ГЕТЕРОСТРУКТУР SI/SIO2/NI

Results of investigations of electrical and magnetoresistive characteristics of Si/SiO2/Ni heterostructures obtained using the swift heavy ion track technology are presented. The presence of a positive magnetoresistance growing up with decreasing temperature and reaching 600 % at T ~ 25 K is determined. This result makes it possible to create highly-sensitive magnetic field sensor devices for space applications, which operates at a liquid hydrogen cooling. The prospects of the creation of magnetic-field sensors using alternating layers of ferromagnetic and nonmagnetic metals in the nanopores are determined. The possibility of application of the «Tunable Electronic Material in Pores in Oxide on Semiconductors» concept on this concern is demonstrated.На основе исследования гетероструктур Si/SiO2/Ni, полученных с использованием метода треков быстрых тяжелых ионов, представлены данные их электрических и магниторезистивных характеристик. Установлено наличие положительного магнитосопротивления, растущего с понижением температуры и достигающего при Т~25 К величины 600 %, что позволяет создать высокочувствительные сенсоры магнитного поля для аппаратуры космического применения, функционирующей при жидководородном охлаждении. Определены перспективы создания сенсоров с использованием чередующихся слоев из ферромагнитных и немагнитных металлов в нанопорах и показана возможность применения концепции «Управляемого электронного материала с порами в оксиде кремния»

Template synthesis and magnetic characterization of FeNi nanotubes

Iron-nickel nanotubes consisting of 20% Ni and 80% Fe with an aspect ratio of about 100 were synthesized by electrochemical deposition in the pores of polyethylene terephthalate ion-track membranes. The main morphological parameters such as composition, wall thickness and structural characteristics were defined. Macro- and micromagnetic parameters of FeNi nanotubes were determined. © 2017, Electromagnetics Academy. All rights reserved

Structural and magnetic studies of FE100–xCox nanotubes obtaine by template method

Hollow nanostructures based on the Fe100–xCox alloy were synthesized in the pores of polymer template matrices based on PET using the electrochemical deposition method. Morphology, elemental composition, and structural features were characterized by scanning electron microscopy, energy dispersive analysis, and X-ray diffractometry. The study of the internal magnetic texture was carried out using Mossbauer spectroscopy. The dependence of the change in structural and magnetic properties from the atomic content of components in nanotube structure is revealed. It is established that the synthesized nanostructures are hollow Fe100–xCox nanotubes with a body-centered cubic crystal structure. The decrease in the unit cell parameter with increasing cobalt concentration is due to the difference in the radii of Fe (1.227 Å) and Co (1.191 Å) atoms. It is established that a random distribution of magnetic moments directions of Fe atoms is observed for Fe100Co0 nanotubes. And magnetic texture along the nanotube axis is observed for Fe100–xCox nanotubes, with an increase in Co atoms concentration. The average angle between the direction of the magnetic moment of iron atoms and the nanotube axis decreases from v = 54:6° to v = 24:5°. © 2018, Electromagnetics Academy. All rights reserved

Influence of deposition potential on structure of Zn-based nanotubes

The rapid growth of the market of electronic devices designed on the base of micro- and nanoelectronic components requires novel unconventional approaches for nanostructures formation. In this regard, ion-track technology, which allows forming nanostructures with a predetermined geometry is very promising. The paper demonstrates a simple and scalable approach to the creation of nanotubes based on pure zinc and its oxide. The main idea of the work is to determine the possibility of controlling of the nanotubes morphology and composition by variation of the deposition potential. In this concern, template synthesis of zincbased nanotubes in the PET template pores is carried out at potentials in the range from 1.25 to 2 V and a comprehensive study of their structural and morphological features is provided. © 2019 Elsevier Ltd

Fe 3 O 4 nanoparticles for complex targeted delivery and boron neutron capture therapy

Magnetic Fe 3 O 4 nanoparticles (NPs) and their surface modification with therapeutic substances are of great interest, especially drug delivery for cancer therapy, including boron-neutron capture therapy (BNCT). In this paper, we present the results of boron-rich compound (carborane borate) attachment to previously aminated by (3-aminopropyl)-trimethoxysilane (APTMS) iron oxide NPs. Fourier transform infrared spectroscopy with Attenuated total reflectance accessory (ATR-FTIR) and energy-dispersive X-ray analysis confirmed the change of the element content of NPs after modification and formation of new bonds between Fe3O4 NPs and the attached molecules. Transmission (TEM) and scanning electron microscopy (SEM) showed Fe3O4 NPs’ average size of 18.9 nm. Phase parameters were studied by powder X-ray diffraction (XRD), and the magnetic behavior of Fe 3 O 4 NPs was elucidated by Mössbauer spectroscopy. The colloidal and chemical stability of NPs was studied using simulated body fluid (phosphate buffer-PBS). Modified NPs have shown excellent stability in PBS (pH = 7.4), characterized by XRD, Mössbauer spectroscopy, and dynamic light scattering (DLS). Biocompatibility was evaluated in-vitro using cultured mouse embryonic fibroblasts (MEFs). The results show us an increasing of IC50 from 0.110 mg/mL for Fe 3 O 4 NPs to 0.405 mg/mL for Fe 3 O 4 -Carborane NPs. The obtained data confirm the biocompatibility and stability of synthesized NPs and the potential to use them in BNCT. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This study was funded by the Ministry of Education and Science of the Republic of Kazakhstan (grant No AP05130947 “Setting the stage for boron neutron capture therapy of cancer in the Republic of Kazakhstan”) and Nazarbayev University “Social Policy Grant” (project title: “Research and development of the new Nano-Optical Sensor based on Polymer Optical Fiber for Near-Field Scanning Optical Microscopy”, PI: Kanat Dukenbayev). The authors also gratefully acknowledge the financial support of the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST «MISiS» (NoK4-2018-036, P02-2017-2-4), implemented by a governmental degree dated 16th of March 2013, No 211. The work was partially supported by Act 211 Government of the Russian Federation, contract No 02.A03.21.0011. This work was partially supported by the Ministry of Education and Science of the Russian Federation (Government task in SUSU 5.5523.2017/8.9)

Catalytic Activity of Ni Nanotubes Covered with Nanostructured Gold

Ni nanotubes (NTs) were produced by the template method in the pores of ion-track membranes and then were successfully functionalized with gold nanoparticles (Ni@Au NTs) using electroless wet-chemical deposition with the aim to demonstrate their high catalytic activity. The fab-ricated NTs were characterized using a variety of techniques in order to determine their morphology and dimensions, crystalline structure, and magnetic properties. The morphology of Au coating de-pended on the concentration of gold chloride aqueous solution used for Au deposition. The catalytic activity was evaluated by a model reaction of the reduction of 4-nitrophenol by borohydride ions in the presence of Ni and Ni@Au NTs. The reaction was monitored spectrophotometrically in real time by detecting the decrease in the absorption peaks. It was found that gold coating with needle-like structure formed at a higher Au-ions concentration had the strongest catalytic effect, while bare Ni NTs had little effect. The presence of a magnetic core allowed the extraction of the catalyst with the help of a magnetic field for reusable applications. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: The work was carried out with the support of the Ministry of Science and Higher Education of the Russian Federation in the framework of the State Task (project code 0718-2020-0037)

Efficiency of Magnetostatic Protection Using Nanostructured Permalloy Shielding Coatings Depending on Their Microstructure

The effect of microstructure on the efficiency of shielding or shunting of the magnetic fluxby permalloy shields was investigated in the present work. For this purpose, the FeNi shieldingcoatings with different grain structures were obtained using stationary and pulsed electrodeposition.The coatings’ composition, crystal structure, surface microstructure, magnetic domain structure, andshielding efficiency were studied. It has been shown that coatings with 0.2–0.6μm grains have adisordered domain structure. Consequently, a higher value of the shielding efficiency was achieved,but the working range was too limited. The reason for this is probably the hindered movement of thedomain boundaries. Samples with nanosized grains have an ordered two-domain magnetic structurewith a permissible partial transition to a superparamagnetic state in regions with a grain size of lessthan 100 nm. The ordered magnetic structure, the small size of the domain, and the coexistenceof ferromagnetic and superparamagnetic regions, although they reduce the maximum value ofthe shielding efficiency, significantly expand the working range in the nanostructured permalloyshielding coatings. As a result, a dependence between the grain and domain structure and theefficiency of magnetostatic shielding was found

The study of the applicability of invar nanostructures for the reduction of p-nitrophenyl compounds

The results of the study of the phase composition of iron-nickel nanostructures susceptible to electron irradiation on the catalytic reduction of p-nitrophenyl compounds are presented. In the course of the studies, it was found that the nanostructures irradiated with a dose of 250 kGy, which are characterized by the presence of two phases, with the domination of the FeNi phase, have the highest recovery rate. In this case, nanostructures irradiated with a dose of 250 kGy, which showed the highest catalytic reaction rate, have a fairly short lifetime, which may be due to the rapid degradation of the surface of the nanotubes as a result of the interaction of the catalyst with the medium. © 2020. All Rights Reserved.This study was funded by the Ministry of Education and Science of the Republic of Kazakhstan (grant AP05133578)

SRIM Simulation of Carbon Ions Interaction with Ni Nanotubes

By template synthesis method nickel nanotubes with diameter of 400 nm and length of 12 μm were produced in the pores of PET template. The nanotubes were modified by irradiation with carbon ions with energy of 28 MeV and a dose of 5 × 1011 cm-2. To ensure the maximum efficiency of nanostructures modification process, energy of irradiation was decided by using of SRIM software. Based on SRIM simulation of carbon ions interaction with Ni nanotubes, the areas on which effect of high energy ions will maximum were predicted. A comparative analysis of nanostructures before and after irradiation was carried out by scanning electron microscopy. The maximum change in nanotubes morphology, in the form of destruction of walls, was appeared at a distance of about 10 μm from the start point of C3+ ions track inside the nanotubes. A substantiation of reason of wall degradation in this area was proposed. © 2019 Elsevier Ltd.Horizon 2020 Framework Programme, H2020: 778308