Dimerization and low-dimensional magnetism in nanocrystalline TiO2 semiconductors doped by Fe and Co

The report is devoted to an analysis of the structural and magnetic state of the nanocrystalline diluted magnetic semiconductors based on TiO2 doped with Fe and Co atoms. Structural and magnetic characterization of samples was carried out using X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), X-ray absorption spectroscopy (XAS), electron paramagnetic resonance (EPR) spectroscopy, SQUID magnetometry, and the density functional theory (DFT) calculations. Analysis of the experimental data suggests the presence of non-interacting paramagnetic Fe3+ and Co2+ ions in the high-spin state and negative exchange interactions between them. The important conclusions is that the distribution of dopants in the TiO2 matrix, even at low concentrations of 3d-metal dopant (less than one percent), is not random, but the 3d ions localization and dimerization is observed both on the surface and in the nanoparticles core. Thus, in the paper the quantum mechanical model for describing the magnetic properties of TiO2:(Fe, Co) was suggested. The model operates only with two parameters: paramagnetic contribution of non-interacting 3d-ions and dimers having different exchange interactions between 3d magnetic carriers. © Published under licence by IOP Publishing Ltd

Unconventional magnetism of non-uniform distribution of Co in TiO2 nanoparticles

High-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) analysis, electron paramagnetic resonance (EPR), X-ray absorption spectroscopy (XAS), magnetic methods, and density-functional theory (DFT) calculations were applied for the investigations of Co-doped anatase TiO2 nanoparticles (∼20 nm). It was found that high-spin Co2+ ions prefer to occupy the interstitial positions in the TiO2 lattice which are the most energetically favourable in compare to the substitutional those. A quantum mechanical model which operates mainly on two types of Co2+ – Co2+ dimers with different negative exchange interactions and the non-interacting paramagnetic Co2+ ions provides a satisfactorily description of magnetic properties for the TiO2:Co system. © 2020 Elsevier B.V.Russian Foundation for Basic Research. Ministry of Science and Higher Education of the Russian Federatio

Theoretical and experimental determination of biomechanics descriptions at run

Определены кинематические и динамические характеристики бега спортсменов. Составлены рекомендации для корректирования движений и улучшения техники движений. Проведена видеосъемка бега на короткие и средние дистанции. Рассмотрены динамические характеристики: сила трения, сила отталкивания, реакция опоры на прямом участке и вираже. Установлено, что максимальные значения силы трения на прямом участке составили 90 Н, нормальная реакция опоры - 595 Н. Максимальные значения силы трения на вираже составили 95 Н, нормальной реакция опоры - 610 Н. Максимальное значение силы отталкивания на прямом участке составило 600 Н, на вираже - 619 Н.Kinematics and dynamic descriptions at run of sportsmen are certain. Made recommendation for adjustment of motions and improvement of technique of motions. A videosurvey at run is conducted on short and middle distances. Dynamic descriptions are considered: force of friction, force of pushing away, reaction of support on a direct area and turn. It is set that maximal values of force of friction on a direct area were 90 N, normal reaction of support - 595 N. Maximal values of force of friction on a turn were 95 N, normal reaction of support - 610 N. Maximal a value of force of pushing away on a direct area was 600 N, on a turn - 619

Application of Nanoparticles with the Structure of the Metal Nucleus - Carbon Enclosure in Biology and Medicine

The study was carried out with the financial support of the Russian Foundation for Basic Research in the framework of the research project No. 18-33-00785