Kirill I. Borodin

In this paper, the electron and magnetic state of iron placed either on the surface or in the core of TiO₂ nanoparticles were investigated using magnetometric methods, electron paramagnetic resonance (EPR) and Mössbauer spectroscopy. It was demonstrated that the EPR spectra of TiO₂ samples with iron atoms localized both on the surface and in the core of specific features depending on the composition and size of the nanoparticles. Theoretical calculations using the density functional theory (DFT) method demonstrated that the localization of Fe atoms on the surface is characterized by a considerably larger set of atomic configurations as compared to that in the core of TiO₂ nanoparticles. Mössbauer spectra of the samples doped with Fe atoms both on the surface and in the core can be described quite satisfactorily using two and three doublets with different quadrupole splitting, respectively. This probably demonstrates that the Fe atoms on particle surface and in the bulk are in different unlike local surroundings. All iron ions, both on the surface and in the core, were found to be in the Fe³⁺ high-spin state.

This work is devoted to the study of the magnetic properties and Electron Paramagnetic Resonance (EPR) spectroscopy of TiO₂:Fe nanoparticles doped with Al in different structural states. The sol-gel methods have been used to obtain the particles in both crystalline (average size from 3 to 20 nm) and X-ray amorphous states. The electron paramagnetic resonance spectra of crystalline samples TiO₂:Fe doped with aluminum besides a resonance line with g-factor ~2 exhibit a small signal with a g-factor of 4.3 from Fe³⁺ ions with rhombohedral distortions. The fraction of Fe³⁺ with rhombohedral distortions increases with increasing aluminum content. For the amorphous state at Al doping, the resonance with a g-factor of 4.3 is completely dominant in the electron paramagnetic resonance spectrum. The density functional theory calculation shows that aluminum prefers to be localized near iron ions, distorting the nearest Fe³⁺ environment. The complex integral electron paramagnetic resonance spectrum of all samples was fitted with sufficient accuracy by three separate resonance lines with different widths and intensities. The temperature behavior of the electron paramagnetic resonance spectrum can be described by the coexistence of paramagnetic centers (isolated Fe³⁺ ions including dipole-dipole interactions) and iron clusters with negative exchange interactions.

The gas solubility in crystals has been studied with regard to interaction between impurity atoms in terms of the kinetic molecular theory of metals and alloys. The dependence of gas solubility versus gas pressure has been found for monoatomic and diatomic gases. It is argued that the deviation of this dependence from Sievert’s laws is due to interaction between impurity atoms.

Within the framework of the molecular kinetic theory of metals and alloys, the solubility of gases in crystals is studied taking into account the interaction between impurity atoms. Dependences of solubility on gas pressure for monatomic and diatomic gases are found. It is stated that deviations from the Sieverts law are due to the interaction between impurity atoms.

The mutual solubilities of all components for the substitution alloy and pure crystal are calculated in the static approximation. Their concentration and temperature dependences are established. The dependences of the solubility of all components on the long-range parameter are found. It is shown that solubility obey the law of Arrhenius.

Our article is devoted to development and verification of the metaheuristic optimisation algorithm in the course of selection of the compositional proportions of the slag-filled concretes. The experimental selection of various compositions and working modes, which ensure one and the same fixed level of a basic property, is the very labour-intensive and time-consuming process. This process cannot be feasible in practice in many situations, for example, in the cases, where it is necessary to investigate composite materials with equal indicators of resistance to aggressive environments or with equal share of voids in the certain range of dimensions. There are many similar articles in the scientific literature. Therefore, it is possible to make the conclusion on the topicality of the above-described problem. In our article, we will consider development of the methodology of the automated experimental-and-statistical determination of optimal compositions of the slag-filled concretes. In order to optimise search of local extremums of the complicated functions of the multi-factor analysis, we will utilise the metaheuristic optimisation algorithm, which is based on the concept of the swarm intelligence. Motivation in respect of utilisation of the swarm intelligence algorithm is conditioned by the absence of the educational pattern, within which it is not necessary to establish a certain pattern of learning as it is necessary to do in the neural-network algorithms. In the course of performance of this investigation, we propose this algorithm, as well as procedure of its verification on the basis of the immediate experimental verification.

The assessment of ionizing radiation impact on the most abundant foods has been performed. The dependencies of food stuffs response on the irradiation dose in time frame were established. The group of foods that gave a weak response to irradiation, as well as a group that becomes quickly irradiated, have been identified. Maximum possible measurement error was up to 10 %.

Mutual solubilities of components for binary interstitial solutions were calculated in static approximation. Temperature and concentration dependences for solubilities were found. It was shown that the solubilities obey the law of Arrhenius.