In self-polarized lead zirconate titanate thin films formed on platinized silicon substrates, a significant increase in the internal electric field was observed as a result of long-term aging. To explain this phenomenon, a mechanism is proposed for the formation of the internal field associated with the diffusion of charged oxygen vacancies, which, in turn, is due to the action of a mechanical stress gradient. The diffusion coefficient of charged oxygen vacancies was estimated to be ~ 3·10-16 cm2/s. Keywords: thin films, lead zirconate titanate, internal field, Gorsky effect.

The paper presents the results of two-layer thin ferroelectric PZT films studies with a change in the lead content over the thickness of the films, obtained by RF magnetron deposition at various pressures of the working gas mixture. The microstructure and elemental composition were investigated by scanning electron microscopy and electron probe X-ray spec-tral microanalysis. It is shown that the elemental composition and dielectric properties depend on the sequence of layers deposition. The results obtained make it possible to characterize the physical mechanism of self-polarization formation in thin PZT films.

The electrophysical properties of a series of PbTe samples doped with Tl and an additional admixture of Na are investigated. Observed features of temperature dependences of electrical conductivity and Hall’s coefficient are explained within the framework of the model of resonant states of thallium, taking into account the complex structure of the valence band. It is shown that the idea of an ideal crystal and a band structure in the framework of the one-electron approximation is insufficient to explain the experimental data on the Hall effect. It is necessary to take into account the modification of the energy spectrum taking into account the statistical distribution of impurities and defects and the additional interaction of particles.

X-ray studies of TlFeS2 and TlFeSe2 crystals grown by high-temperature synthesis reveal their single-phase nature and isostructurality with the space group C2/m. Raman scattering and infrared reflection of light in TlFeS2 and TlFeSe2 compounds is studied at a temperature of 300 K. Characteristic frequencies in the Raman scattering and infrared spectra of phonons in TlFeS2 and TlFeSe2 are detected. An analysis of published works on the magnetic properties of TlFeS2 and TlFeSe2 allows the conclusion that they are quasi-one-dimensional antiferromagnets each having two characteristic temperatures TN3D and $$T_{c}^{{{\text{super-p}}}}$$ , between which quasi-one-dimensional antiferromagnetic ordering in TlFeS2 and TlFeSe2 is favorable. The temperature $$T_{c}^{{{\text{super-p}}}}$$ is introduced for the first time and characterizes a highly developed short-range magnetic order, in which superparamagnetic ordering exists.

A novel computationally effective approach to multiscale thermoelastic modelling of composite structures and its application to a thermomechanical analysis of two ITER superconducting strands is presented. Homogenisation and recovering problems are solved by means of the “fundamental solutions” method, which was expanded to the case of thermoelastic analysis. We describe a general procedure of multiscale analysis on the basis of this method and apply it to recover stresses at the microscopic scale of a composite strands using a two-level procedure. The recovered micro-stresses are found to be in good correlation with the stresses obtained in the reference problem where the entire composite structure was modelled with a fine mesh.

By spectroscopic ellipsometry, the imaginary and real parts of the dielectric functions of Bi 2 Se 3 and Bi 2 Se 3 〈Cu〉 single crystals are obtained in the photon-energy range from 0.7 to 6.5 eV, and the energies of allowed direct transitions responsible for some optical properties are determined. Using the Cody–Lorentz optical oscillator and the Lorentz optical oscillator, the dispersion relation is adjusted in conformity with the experimental data. The values of the refractive index ( n ) and extinction coefficient ( k ) of the Bi 2 Se 3 single crystals are calculated in the energy range from 0.7 to 6.5 eV. It is established that the maximum absorption corresponds to the energies of 1.900 and 1.949 eV for Bi 2 Se 3 and Bi 2 Se 3 〈Cu〉, respectively.

This paper presents the results of a study of the electrical conductivity coefficient, the Hall coefficient, the Seebeck coefficient, the transverse Nernst-Ettingshausen coefficient and their anisotropy in a Bi2Te3 single crystal with a hole concentration p =1 × 1019 cm–3 at temperatures 77–350 К. It is established that hole scattering occurs mainly on long-wave acoustic phonons. Despite the fact thatthe chemical potential level is located near the top of the additional extreme of the valence band, no interband scattering was detected. The complex structure of the valence band is confirmed.

X ray studies of T1FeS(2) and T1FeSe(2) crystals grown by high-temperature synthesis reveal their single-phase nature and isostructurality with the space group C2/m. Raman scattering and infrared reflection of light in T1FeS(2) and T1FeSe(2) compounds is studied at a temperature of 300 K. Characteristic frequencies in the Raman scattering and infrared spectra of phonons in T1FeS(2) and T1FeSe(2) are detected. An analysis of published works on the magnetic properties of T1FeS(2) and T1FeSe(2) allows the conclusion that they are quasi- one-dimensional antiferromagnets each having two characteristic temperatures T-N3D and T-c(super-P), between which quasi-one-dimensional antiferromagnetic ordering in T1FeS(2) and T1FeSe(2) is favorable. The tempera- ture T-c(super-P) is introduced for the first time and characterizes a highly developed short-range magnetic order, in which superparamagnetic ordering exists.

The RF magnetron sputtering of a PZT ceramic target with a variation in the pressure of the working gas is used to form two two-layer thin-film structures differing in the sequence of layer deposition: structure “A” is deposited at a pressure of 4 and 8 Pa, and structure “B” is deposited at a pressure of 8 and 4 Pa. The total thickness of the structures is ~920 nm. An oxidized silicon wafer and an oxidized silicon wafer with a deposited platinum electrode serve as the substrates. The structures are subjected to high-temperature annealing at 570°C to crystallize the perovskite phase. Their microstructure and elemental composition are investigated with scanning electron microscopy and X-ray microanalysis. The dielectric properties are studied using an E7-20 immittance meter and a modified Sawyer–Tower circuit. The formed thin layers are characterized by a predominant 〈110〉 growth texture. It is shown that the elemental composition and dielectric properties depend on the sequence of deposition of layers. In both structures, the crystallization of the perovskite phase begins in a layer deposited at a pressure of 8 Pa enriched with excess lead, and spreads to the layer with a lower lead content deposited at a pressure of 4 Pa. Structure “B” was characterized by almost complete crystallization into the perovskite phase, the smaller segregation of titanium and zirconium atoms over the structure thickness, a higher dielectric constant, and asymmetry of the dielectric hysteresis loops and reversible dependence of the dielectric constant, which indicate the presence of an internal field and spontaneous polarization. The results obtained make it possible to specify the physical mechanism of the formation of self-polarization in thin PZT films, and also suggest one of the ways to reduce elemental inhomogeneity over thickness, which allows maximization of the dielectric and electromechanical parameters of films, whose composition corresponds to the region of the morphotropic phase boundary.

In self-polarized lead zirconate titanate thin films formed on platinized silicon substrates, a significant increase in the internal electric field was observed as a result of long-term aging. To explain this phenomenon, a mechanism is proposed for the formation of the internal field associated with the diffusion of charged oxygen vacancies, which, in turn, is due to the action of a mechanical stress gradient. The diffusion coefficient of charged oxygen vacancies was estimated to be ∼ 3 × 10–16 cm2/s.

X-ray studies of TlFeS 2 and TlFeSe 2 crystals grown by high-temperature synthesis reveal their single-phase nature and isostructurality with the space group C2/m. Raman scattering and infrared reflection of light in TlFeS 2 and TlFeSe 2 compounds is studied at a temperature of 300 K. Characteristic frequencies in the Raman scattering and infrared spectra of phonons in TlFeS 2 and TlFeSe 2 are detected. An analysis of published works on the magnetic properties of TlFeS 2 and TlFeSe 2 allows the conclusion that they are quasi-one-dimensional antiferromagnets each having two characteristic temperatures T N3D and T_c^super-p , between which quasi-one-dimensional antiferromagnetic ordering in TlFeS 2 and TlFeSe 2 is favorable. The temperature T_c^super-p is introduced for the first time and characterizes a highly developed short-range magnetic order, in which superparamagnetic ordering exists.

Рентгеновские исследования кристаллов TlFeS2, TlFeSe2, полученных методом высокотемпературного синтеза, выявили их монофазность и изоструктурность с пространственной группой симметрии С2/m. Исследованы комбинационное рассеяние света и инфракрасное отражение света в соединениях TlFeS2, TlFeSe2 при температуре 300 K. Обнаружены и определены характерные частоты в рамановском рассеянии и инфракрасных спектрах фононов в TlFeS2, TlFeSe2. Из анализа опубликованных работ по магнитным свойствам TlFeS2, TlFeSe2 сделано заключение, что они являются квазиодномерными антиферромагнетиками, каждый из которых обладает двумя характеристическими температурами, TN3D и T_csuper-p, между ними и располагается квазиодномерное антиферромагнитное упорядочение в TlFeS2, TlFeSe2. Температура T_csuper-p введена впервые и характеризует сильно развитый ближний магнитный порядок, в котором существует суперпарамагнитное упорядочение. Ключевые слова: оптические фононы, комбинационное рассеяние света, инфракрасное отражение света, монофазность и изоструктурность кристаллов, квазиодномерные антиферромагнетики.

The article analyses the existing set of data on the temperature dependences of the main kinetic coefficients and the IR-reflection spectra R(ν) of the PbSb2Te4 crystals. The form of the Fermi surface is discussed. The anisotropy of holes’ effective mass and relaxation time is estimated. The complex structure of the valence zone is confirmed, the values of these parameters are refined. Complex X-ray studies of the structure and composition of PbSb2Te4 samples gave the possibilities to clarify the real crystal structure and explain the number of features in the IR-reflection spectra.

The efficiency of using a diamagnetic screen with inertial retention in a non-destructive quasi-force-free magnet of a small volume (with a characteristic dimension about 10 cm 3 ) for generating a superstrong magnetic field with a pulse duration of about 10 µs is shown. A configuration of the magnet was developed, in which the end part of the winding is balanced due to the fact that the screen virtually does not move during the discharge. Mechanical stresses in the winding were calculated, and it was demonstrated that mechanical strength of the winding can be ensured in a field with magnetic flux density up to 100 T. Calculations of the heating of the winding were performed and the possibilities of its reduction to an acceptable level are indicated.

The efficiency of using a diamagnetic screen with inertial retention in a non-destructive quasi-force-free magnet of a small volume (with a characteristic dimension about 10 cm^3 ) for generating a superstrong magnetic field with a pulse duration of about 10 µs is shown. A configuration of the magnet was developed, in which the end part of the winding is balanced due to the fact that the screen virtually does not move during the discharge. Mechanical stresses in the winding were calculated, and it was demonstrated that mechanical strength of the winding can be ensured in a field with magnetic flux density up to 100T. Calculations of the heating of the winding were performed and the possibilities of its reduction to an acceptable level are indicated.

In this work, by spectroscopic ellipsometry the imaginary and real parts of the dielectric function of Bi2Se3 and Bi2Se3 single crystals were obtained in the photon energy range from 0.7 eV to 6.5 eV, and were determined the energies of allowed direct transitions responsible for some optical properties. By the help of Cody-Lorentz and Lorentz optical oscillators, the dispersion relation is adjusted in conformity with the experimental data. The values of the refractive index n and the extinction coefficient k of Bi2Se3 single crystals are calculated in the energy range from 0.7 eV to 6.5 eV. It was also determined that the maximum absorption corresponds to the transitions at 1.900 eV and 1.949 eV for Bi2Se3 and Bi2Se3, respectively.

Generation of ultrahigh hydrostatic pressure by application of a strong one-axis deformation is demonstrated in epitaxial ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$ films on a mica substrate. This was followed by measurements of transport properties in $n$-type ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$ as a function of temperature (100--300 K) and pressure of up to 30 kbar. This pressure allowed studies of the restructuring of the conduction band. The nonmonotonic pressure dependence of the Hall coefficient and the increase of electrical conductivity \ensuremath{\sigma}($P$) can only be explained using two subband structures in the conduction band: subbands of light and heavy electrons with a mobility ratio of 10. The gap between the electron subbands increases with the hydrostatic pressure.

By spectroscopic ellipsometry, the imaginary and real parts of the dielectric functions of Bi2Se3 and Bi2Se3〈Cu〉 single crystals are obtained in the photon-energy range from 0.7 to 6.5 eV, and the energies of allowed direct transitions responsible for some optical properties are determined. Using the Cody–Lorentz optical oscillator and the Lorentz optical oscillator, the dispersion relation is adjusted in conformity with the experimental data. The values of the refractive index (n) and extinction coefficient (k) of the Bi2Se3 single crystals are calculated in the energy range from 0.7 to 6.5 eV. It is established that the maximum absorption corresponds to the energies of 1.900 and 1.949 eV for Bi2Se3 and Bi2Se3〈Cu〉, respectively.