Temperature evolution of dielectric response, atomic structure, and lattice dynamics in thin film of sodium niobate in the epitaxial NaNbO3/SrRuO3/(001)MgO heterostructure is studied by dielectric measurements, x-ray diffraction, and Raman spectroscopy. It is found that at room temperature NaNbO3 is in ferroelectric state, whereas the temperature-dependent dielectric constant experiences a broad maximum at 440 K on cooling and at 500 K on heating and reveals a diffuse phase transition. Reciprocal space mapping shows the presence of both anti-phase and in-phase tilting of oxygen octahedra. The temperature dependence of the M-point reflections suggests reorientation of the in-phase octahedra tilting axis from being parallel to the substrate at room temperature to perpendicular orientation at high temperatures. The temperature evolution of the shape of the Raman spectra reveal the decrease of the number of constituting peaks on heating. These results are interpreted as indicating a temperature-driven transition between two different orientations of the bulk ferroelectric Q phase with respect to the interface, namely between the state with electric polarization pointing at ≈ 45 • to the normal at room temperature to the state with polarization parallel to the interface above the transition. Transitions of this kind can be anticipated from theoretical considerations, while the experimental evidences of such are yet scarce.
This paper focuses on the impact of certain factors on the contemporary distribution of natural (226Ra, 232Th, 40К) and anthropogenic (137Cs, 60Co) Key words: radionuclide distribution patterns, Baltic Sea, hydromica, pH barrier, sediment fractions, grain-size composition.A number of researchers have studied the features of migration and accumulation of natural and anthropogenic radionuclides. In particular, one of the fundamental works is Artificial radionuclides in marine environment by V. V. Gromov and V. I. Spitsin [6] dedicated to the problems of migration and sorption of anthropogenic radionuclides in oceans. A significant contribution to the study of this issue has been made by I. Ye. Starik, A. P. Lisitsyn, N. M. Strakhov, G. G. Matishev and D. G. Matishev, V. P. Tishkov, V. V. Anisimov, and many others. However, these researchers have focused mainly on radionuclide distribution and behaviour in oceans, at significant depths, in certain sedimentation conditions, and in the presence of long-lasting processes of radionuclide migration in the aquatic environment. The conditions of migration and accumulation of main gamma-emitting radionuclides in the bottom sediment in a relatively shallow basin of the Baltic Sea with dramatic changes in the bathymetric level, the composition of bottom sediment, redox and acidbase characteristics and a significant amount of substances coming from the shore have specific features and are of special interest. Another important aspect of the issue is the immediate influence of the "Chernobyl trace" on the water area of the Baltic Sea.
This article presents an analysis of the possibilities of using Blockchain technology within the framework of programs for the digitalization of the economy and the development of the educational sector. Three main areas of blockchain use are highlighted: cryptocurrencies, tracking the uniqueness of items, and smart contracts. A classification of blockchainbased systems is also proposed, dividing systems by volume. The modern methods of using this technology for the implementation of various tasks at the level of particular companies, countries and the world are considered, and a promising solution is proposed in accordance with modern trends and directions of development. The problems related to the implementation of blockchain systems are also suggeste
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