Since the energy spectrum of bismuth charge carriers is highly sensitive to mechanical deformations, studying their influence, leading to an increase or decrease in the overlap of actual extrema, on the transport properties of charge carriers in ultrathin bismuth films makes it possible to investigate the combination of manifestations of the quantum size effect and metallic surface states. In this work, the temperature dependencies of the electrical and galvanomagnetic properties of thin bismuth films (10-1250 nm) are studied under conditions of in-plane tensile and compressive deformation. Deformations are created as a result of the difference in the coefficients of thermal expansion of the film and substrate materials. Silicon with an oxidized surface, mica, and polished cleavage (111) CaF2 F 2 are used in order to create either tensile and compressive deformations. The presence of film deformations is confirmed by XRD. The magnitude of deformation is calculated based on the CTEs of the materials. The absence of mechanical stress relaxation or the formation of additional defects during temperature measurements is confirmed by the absence of hysteresis of properties in the range of 77-300 K. Based on the experimental results, the mobilities and concentration of charge carriers are calculated within the framework of the two-band model. As the film thickness decreases to less than 100 nm, an increase in the charge carrier concentration is observed, which is associated with metallic surface states. It is shown that the magnitude of the effect of deformation on the concentration of charge carriers in films of all thicknesses remains unchanged.

The paper presents the results of a study of the electrical, galvanomagnetic, and thermoelectric properties of Bi and Bi1-xSbx (x = 0.03, 0.05, and 0.12) thin films (10-50 nm) on a mica substrate. All samples are characterized by an increase in conductivity with a de-crease in film thickness, which can be associated with the presence of topologically protected surface states. It has been found that the band structure of the alloys significantly affects the appearance of the metallic type of conductivity in films with a < 18 nm thickness. It was found that the resistivity of Bi0.97Sb0.03 films < 17 nm thick is almost independent of temperature. Despite the increase in the conductivity of the samples, with a decrease in the thickness, the thermoelectric power factor decreases, which casts doubt on the fact that surface states have a positive effect on the thermoelectric figure of merit of thin Bi1-xSbx films. However, the detection of a positive thermoelectric power in Bi0.88Sb0.12 samples may be of interest in the development of the p branch of thermoelectric converters.

Near the melting temperature, equilibrium bismuth melt is characterized by structural features that are absent in equilibrium monatomic simple liquids. In the present work, the structure of bismuth melt is studied by X-ray diffraction experiments and quantum chemical calculations. The presence of quasi-stable structures in the melt has been found, the lifetime of which exceeds the structural relaxation time of this melt. It is shown that these structures are characterized by a low degree of ordering and spatial localisation. It was found that up to 50% of the atoms in the melt can be involved in the formation of these structures. The elementary structural units of these structures are triplets of regular geometry with the characteristic lengths 3.25 Å and 4.7 Å as well as with the characteristic angles 45∘ and 90∘. The characteristic lengths of these triplets are fully consistent with correlation lengths associated with the short-range order in bismuth melt.

The results of a study of the semimetal films deformation produced by dome bending of the substrate are presented. Deformation control was carried out by means of X-ray diffraction analysis. It is shown that the dome bending method can be used to study films under planar deformation in a film-substrate system with different thermal expansion coefficients. The maximum in-plane deformation for bismuth films of 1 mkm thickness order was found. It was shown that the deformation created by the dome bending of the substrate in combination with the use of substrates with different temperature expansion makes it possible to obtain a relative in-plane deformation of bismuth films up to 0.8% at 300 K.

This paper presents the results of studying the magnitude of the strain of semimetal films created by the dome bending of the substrate. The deformation is controlled by X-ray diffraction (XRD) analysis. It is shown that the dome bending method can be used to study films under conditions of the in-plane deformation that occurs in the film-substrate system due to the difference in the coefficients of thermal expansion of the film and substrate material. It is established that the deformation created by the dome bending of the substrate in combination with the use of substrates with a different thermal expansion makes it possible to obtain a relative in-plane deformation of bismuth films up to 0.8% at 300 K.

The reasons for increasing the charge carriers concentration in thin bismuth films are discussed. The concentration was calculated on the basis of the measured electrical and galvanomagnetic coefficients at the temperature 77K under the two-band approximation and the assumption that the charge carriers free path in the film is isotropic.

The study of the electronic properties of ultrathin films of pure bismuth and bismuth-antimony alloys is of interest, since an increase in conductivity with decreasing sample thickness was found. This paper presents the results of an experimental study of the structure, electrical, galvanomagnetic and thermoelectric properties of pure bismuth and Bi1-xSbx thin films (x=0.05 and 0.12) on a mica substrate in the thickness range of 10-30 nm. An increase in the conductivity with a decrease in the thickness of the samples was found. It may be due to the presence of topologically protected surface states. It is shown that the features of the manifestation of this effect are significantly influenced by the alloys band structure. The form of the temperature dependences of the Seebeck coefficient casts doubt on the fact that surface states have a positive effect on the thermoelectric efficiency of thin bismuth-antimony films. However, the detection of a positive thermoelectric power in Bi0.88Sb0.12 samples can become an important factor for searching for the possibility of creating a p-branch of thermoelectric converters. Keywords: bismuth, antimony, thin films, surface states, thermoelectric power.

The reasons for increasing the charge carriers concentration in thin bismuth films are discussed. The concentration was calculated on the basis of the measured electrical and galvanomagnetic coefficients at the temperature 77 K under the two-band approximation and the assumption that the charge carriers free path in the plane of the film is isotropic. Keywords: Bismuth, thin film, charge carriers concentration, surface.

The study of the electronic properties of ultrathin films of pure bismuth and bismuth-antimony alloys is of interest, since an increase in conductivity with decreasing sample thickness was found. This paper presents the results of an experimental study of the structure, electrical, galvanomagnetic and thermoelectric properties of pure bismuth and Bi1−x Sbx thin films (x = 0.05 and 0.12) on a mica substrate in the thickness range of 10−30 nm. An increase in the conductivity with a decrease in the thickness of the samples was found. It may be due to the presence of topologically protected surface states. It is shown that the features of the manifestation of this effect are significantly influenced by the alloys band structure. The form of the temperature dependences of the Seebeck coefficient casts doubt on the fact that surface states have a positive effect on the thermoelectric efficiency of thin bismuth-antimony films. However, the detection of a positive thermoelectric power in Bi0.88Sb0.12 samples can become an important factor for searching for the possibility of creating a p-branch of thermoelectric converters.

The results of studying the resistivity, magnetoresistance, and Hall coefficient of thin films of bismuth and the bismuth–antimony system on a borosilicate-glass substrate under plane tensile strain are presented. Deformation is created by a specially developed method that allows a change in its magnitude directly during measurement of the film properties. The films are obtained by thermal evaporation in vacuum. Varying the technological modes made it possible to obtain films of various structures: from small blocks to single crystal. Based on the experimental results, within the framework of the two-band approximation, the concentrations of charge carriers and the positions of the energy extrema of the valence and conduction bands relative to the chemical potential level are calculated. It is shown that the two-band approximation is insufficient for describing the properties of films of the studied compositions under plane tensile strain.

The paper presents the results of measuring the thermopower and resistivity of bismuth films in the thickness range from 1 μm to 10 nm, obtained by thermal evaporation in vacuum. The study is carried out in the temperature range 77–300 K by a method excluding the introduction of additional deformation into the film-substrate system by elements of the measuring cell. Plates of single-crystal mica (muscovite) are used as substrates. A significant dependence of the thermopower and thermoelectric power on the film thickness is found. The results are interpreted within the framework of classical and quantum-size effects of the restriction of the thickness and size of crystallites.

Gas turbine power plants based on converted aircraft engines have been successfully produced in Perm city since 1991. Their power range is steadily expanding. Such gas turbine electro power stations have significant advantages. However, the need to make full use of these advantages requires power station control processes significant intellectualization. Intellectualization will provide an opportunity to improve the electricity quality, increase the power supply reliability and improve environmental friendliness. To achieve these goals, it is necessary to study the behavior of gas turbine power electro station in different operation modes and in various configurations power system. Such research can only be carried out on the basis of mathematical models. Moreover, these models should be high-speed, since the research of control algorithms requires a large number of various experiments in a limited time. One of the promising ways to obtain such mathematical models is to use the artificial neural networks apparatus. To construct a gas turbine power electro station mathematical model, it is necessary to choose such a neural network architecture that will allow obtaining a model for an acceptable period of time and will allow modeling the processes with the required accuracy. Therefore, the problem of choosing the neural network architecture is an urgent research priority. On the basis of the performed studies, the architecture of a neural network for modeling various configurations power system is proposed and substantiated.

Abstract—A method for creating single-crystal bismuth films by melting and subsequent normal directed crystallization without a seed under a protective coating in a nitrogen atmosphere is proposed and tested. The high quality of the crystal structure of these films is confirmed by atomic-force microscopy and X-ray diffraction analysis. The specific resistance, magnetoresistance, and Hall coefficient are measured in the temperature range of 77–300 K. The electrical and galvanomagnetic coefficients of single-crystal bismuth films are compared with similar coefficients for block bismuth films created by thermal evaporation in vacuum. The mobilities of electrons and holes are determined in the temperature range 77–300 K for the studied structures.

of scientific reports for the XVIII International Forum on Thermoelectricity in the following lines: theory of thermoelectricity metrology in thermoelectricity, thermoelectric material science, thermoelectric devices and instruments

The dependences of the resistivity, magnetoresistance,and Hall coefficient on the sample thickness were studied forthin bismuth films on mica at 77 K. We discovered quantum sizeoscillations of electrical and galvanomagnetic properties for filmswith the thickness less than 50 nm. The charge carrier free path isestimated. The reasons for deviation of the observed experimentaldependences from the simple quantum size effect theory in thesemimetal films are discussed.

The results of an investigation into the thermoelectric power of thin block Bi1 –xSbx films (0 ≤ x ≤ 0.15) 100–1000 nm in thickness on mica and polyimide substrates in the temperature range of 77–300 K are presented. When measuring the thermoelectric power, a method excluding strain distortion in the film–substrate system is used. The structure, temperature dependences of the thermoelectric power, and resistivity of thin films are analyzed, and the power factor is estimated. A difference in the character of the temperature dependences of the thermoelectric power and resistivity of the films on mica and polyimide substrates is found. This difference is explained by a variation in the band structure parameters under the effect of strain appearing in the film–substrate system due to a difference in the thermal expansion of the film and substrate materials.

The report presents the positions of the conductance and valence band extremes in relation to the chemical potential of the thin bismuth–antimony films (from 0 to 15 at% Sb) on substrates with different thermal expansion. The results are based on the galvanomagnetic properties study of thermal deposited thin films. A significant increase in the concentration of charge carriers in films on substrates with a large thermal expansion was found. The results of calculating the valence band and the conduction band positions at 77 K, depending on the thermal expansion coefficient of the substrate used, are presented. The thin films plane deformation caused by the difference in the film and substrate materials thermal expansion leads to a change in the positions of the conduction band and the valence band of the films relative to their positions in a single crystal with corresponding composition

The results of calculation of the charge-carrier concentration in bismuth–antimony films on substrates with different coefficients of thermal expansion are reported. The antimony content in the films is in the range 0–15 at %. Calculation is performed on the basis of experimental studies of the galvanomagnetic properties of the films. It is shown that the concentration is considerably higher in the case of substrates with a large coefficient of thermal expansion. The results of calculation of the position of the valence and conduction bands at 77 K in relation to the coefficient of thermal expansion of the substrate are reported. It is shown that, as the thin films experience in-plane strains defined by a difference between the coefficients of thermal expansion of the film and substrate materials, the position of the valence and conduction bands in the films changes relative to the position of the bands in the single crystal with the corresponding composition.