A diagnostic system for Thomson scattering of the central, edge and divertor plasma regions of a tokamak with reactor technologies is discussed. The rationale and choice of technical solutions are given, the composition of the Thomson scattering diagnostic complex is discussed, as well as an estimate of the accuracy of measuring the electron temperature and plasma density in the central edge and divertor regions of the TRT tokamak. Particular attention is paid to ensuring the functionality of the proposed diagnostics in the reactor mode of the tokamak operation and the results of testing diagnostic equipment in experiments on the Globus-M2 tokamak.

Thomson scattering of the core edge and divertor plasma regions of a tokamak with reactor technologies is discussed. The rationale and choice of technical solutions are given, the composition of the Thomson scattering diagnostic complex is discussed, as well as an estimate of the accuracy of measuring both electron temperature and density. Particular attention is paid to ensuring the functionality of the proposed diagnostics in the reactor mode of the tokamak operation and the results of testing diagnostic equipment in the experiments on Globus-M2 tokamak.

The samples of the C-Y2O3 compounds doped with photoluminescence activators Tb3+ and Eu3+ with the concentration of 3 and 3.5 mol

Dielectric and acoustic studies of solid solutions were carried out (1-x)SrTiO 3 -xSrMg 1/3 Nb 2/3 O 3 . The dependence of the temperature of the antiferrodisorsion phase transition on the concentration x of the second component is obtained. The suppression of dielectricrelaxation at x≤0.03 and temperatures below the temperature of the antiferrodisorsion transition, as well as the coexistence of dielectric relaxation and antiferrodisorsion instability at 0.03<x≤0.15. The reasons for the blurring of the dependence of the relative speed of sound in the transition region and the features of the interaction of antiferrodisorsion instability and the dielectric subsystem are discussed. Keywords: antiferrodisorsion transition, dielectric relaxation, acoustic properties. Keywords: antiferrodisorsion transition, dielectric relaxation, acoustic properties.

Samples of Gd2O3:Tb(3 mol%) phosphor were obtained by sol-gel method followed by annealing at 800oC and 1200oC in air. At high annealing temperature, the intensities of the main emission bands 484 and 541 nm increase, but the ratio of the intensities of these emission bands to their satellites 493 and 549 nm respectively decreases. Based on the analysis of X-ray diffractometry, radiation spectra, far-infrared and Raman spectroscopy, as well as diffuse reflectance spectroscopy, we established: the increase in the crystallinity of the samples with a significant reduction of the lattice strain stress at elevated annealing temperatures, changes in the structure of the bandgap with degenerated acceptor and donor zones of impurities Tb4+ and Tb3+ respectively. The diffuse reflection spectra of the sample after annealing at 800oC under optical excitation showed a direct charge transition through the bandgap with Eg = 2.56 eV. After elevated annealing temperature the concentration of Tb4+ ions decreases due to reduction to Tb3+. As a result, at low excitation energies the degeneracy of the acceptor zone is still preserved and there is a direct transition of charges through the bandgap with Eg = 2.55 eV. At high excitation energies the degeneracy of the acceptor zone is removed and there is a direct transition through the bandgap with Eg = 3.39 eV. These effects are accompanied by a relatively large increase in the emission intensity of the satellites, especially at the 549 nm.

The Y2O3@SmS composite with a core-shell nanostructure was synthesized using the polyol sol-gel method. For the first time the oxide powder Y2O3@Sm2O3 precursor was obtained from Y2O3 and Sm(acac)(3) solutions in diatomic alcohol ethylene glycol C2H4(OH)(2) by the precipitation of urea (NH2)(2)CO. Next, the precursor was heated to 633 K in the sulfidation atmosphere and annealed at 1423 K to obtain the final Y2O3@SmS composite. It was found that Y2O3@SmS compound contains a small amount of Sm2S3 impurity phase due to the diffusion process of the sulfur atoms of SmS2 phase to the sample surface, followed by a transition of SmS2 to Sm2S3 phase. The short-range order was analyzed using both Raman and XPS spectroscopy. The obtained data showed that Y2O3@SmS composite has a core-shell structure. Y2O3 phase was considered as a core, and the SmS phase - as the shell. Using the SEM and HRTEM data it was found that synthesized sample contained a significant amount of the core-shell nanoparticles with the average size of similar to 200 nm. The Seebeck coefficient was of -40 mu V/K at 430 K. The obtained value was two times greater compared to SmS@Y2O2S and (YO2S)-O-2@SmS core-shell compounds studied previously.

— We report the preparation of SmS@Y 2 O 2 S and Y 2 O 2 S@SmS ceramics with a core–shell nanostructure via 1123-K sulfidation of rare-earth oxides prepared by the sol–gel method, involving precipitation from starting metal nitrate solutions with NH 4 OH as a precipitant, followed by annealing of the resultant sulfide phases in an induction furnace at 1473 K. Using X-ray diffraction and scanning electron microscopy data, we have evaluated the average crystallite size in the materials and examined the morphology of the constituent phases in them. In addition, the short-range order in the coexisting nanostructures has been analyzed in detail using Raman spectroscopy and X-ray photoelectron spectroscopy data.

Samples of Gd 2 O 3 : Tb(3 mol%) phosphor were obtained by sol-gel method followed by annealing at 800 o C and 1200 o C in air. At high annealing temperature, the intensities of the main emission bands 484 and 541 nm increase, but the ratio of the intensities of these emission bands to their satellites 493 and 549 nm respectively decreases. Based on the analysis of X-ray diffractometry, emission spectra, far-infrared and Raman spectroscopy, as well as diffuse reflectance spectroscopy, we established: the increase in the crystallinity of the samples with a significant reduction of the lattice strain stress at elevated annealing temperatures, changes in the structure of the bandgap with degenerated acceptor and donor zones of impurities Tb 4+ and Tb 3+ respectively. The diffuse reflection spectra of the sample after annealing at 800 o C under optical excitation showed a direct charge transition through the bandgap with E g =2.56 eV. After elevated annealing temperature the concentration of Tb 4+ ions decreases due to reduction to Tb 3+ . As a result, at low excitation energies the degeneracy of the acceptor zone is still preserved and there is a direct transition of charges through the bandgap with E g =2.55 eV. At high excitation energies the degeneracy of the acceptor zone is removed and there is a direct transition through the bandgap with E g =3.39 eV. These effects are accompanied by a relatively large increase in the emission intensity of the satellites, especially at the 549 nm. Keywords: Gd oxide, Tb 3+ + photoluminescence spectra, far infrared and Raman spectroscopy spectra, structure of the bandgape, distribution of Tb 3+ and Tb 4+ in cation sublattice.

Samples of Gd2O3:Tb(3 mol%) phosphor were obtained by sol-gel method followed by annealing at 800oC and 1200oC in air. At high annealing temperature, the intensities of the main emission bands 484 and 541 nm increase, but the ratio of the intensities of these emission bands to their satellites 493 and 549 nm respectively decreases. Based on the analysis of X-ray diffractometry, radiation spectra, far-infrared and Raman spectroscopy, as well as diffuse reflectance spectroscopy, we established: the increase in the crystallinity of the samples with a significant reduction of the lattice strain stress at elevated annealing temperatures, changes in the structure of the bandgap with degenerated acceptor and donor zones of impurities Tb4+ and Tb3+ respectively. The diffuse reflection spectra of the sample after annealing at 800oC under optical excitation showed a direct charge transition through the bandgap with Eg = 2.56 eV. After elevated annealing temperature the concentration of Tb4+ ions decreases due to reduction to Tb3+. As a result, at low excitation energies the degeneracy of the acceptor zone is still preserved and there is a direct transition of charges through the bandgap with Eg = 2.55 eV. At high excitation energies the degeneracy of the acceptor zone is removed and there is a direct transition through the bandgap with Eg = 3.39 eV. These effects are accompanied by a relatively large increase in the emission intensity of the satellites, especially at the 549 nm.

The lattice disorder of different architecture and dimensions influence on the thermoelectric properties (Seebeck coefficient S, resistivity , total thermal conductivity κtot, power factor S2/, figure of merit ZT) of the polycrystalline ternary sulfides MTS3 was studied. The high-temperature misfit layered compounds (MS)zNbS2 (MS is GdxDy1-xS solid solutions) were chosen as objects of the study. The variation of gadolinium concentration along the series x = 0.0, 0.1, 0.2, 0.5, 1.0 allowed one to alter the short-range and the long-range order of the crystal lattice and to study their effect on thermoelectric parameters of (GdxDy1-xS)zNbS2. At low concentration of x = 0.1 the crystallite size increases, cause the deformation stresses decrease and, thereby, leads to an abnormal changes of S, , κtot values and ZT decrease. An increase of the gadolinium concentration (x = 0.2–0.5) alters the electronic structure and the interatomic bonding character of the incommensurate subsystems (GdxDy1-xS) and NbS2. In this case, S and  values remains practically unaffected, while the thermal conductivity value decreases by 40% and ZT increases by 2 times. The nature of this phenomenon and the anisotropy of the thermoelectric properties were discussed.

Проведены диэлектрические и акустические исследования твердых растворов (1-x)SrTiO 3 -xSrMg 1/3 Nb 2/3 O 3 . Получена зависимость температуры антиферродисторсионного фазового перехода от концентрации x второй компоненты. Обнаружено подавление диэлектрической релаксации при x≤0.03 и температурах ниже температуры антиферродисторсионного перехода, а также сосуществование диэлектрической релаксации и антиферродисторсионной неустойчивости при 0.03<x≤0.15. Обсуждаются причины размытия зависимости относительной скорости звука в области перехода и особенностей взаимодействия антиферродисторсионной неустойчивости и диэлектрической подсистемы. Ключевые слова: антиферродисторсионный переход, диэлектрическая релаксация, акустические свойства.

The Seebeck coefficient, the electrical resistivity, the total thermal conductivity and the thermoelectric figure of merit of Y2O2S@SmS and SmS@Y2O2S ceramic samples with core-shell nanostructure within the temperature range from 300 to 770 K was studied. It was found that the samples studied demonstrate a promising thermoelectric property in high temperature region (T >= 773 K). The thermoelectric parameters for SmS@Y2O2S of S = -30 mu V/K, rho = 0.53 mu f center dot m and ctot = 2.60 W/m center dot K at T = 773 K were measured. These values result in increased ZT value of 0.48 at T = 773 K in comparison with those for lanthanide-based thermoelectric materials.

The comprehensive study of the electronic density distribution of CuCr 0.99 Ln 0.01 S 2 (Ln = La, Ce) solid solutions was carried out using both X-ray photoelectron and emission spectroscopy. It was found that cationic substitution of chromium with lanthanum or cerium atoms does not significantly affect the atomic charges of the matrix elements (Cu, Cr, S) in the lanthanide-doped solid solutions. The copper atoms in the composition of CuCrS 2 -matrix and the lanthanide-doped solid solutions were found to be in the monovalent state. The chromium and lanthanide atoms were found to be in the trivalent state. This fact indicates the isovalent cationic substitution character. The sulfur atoms were found to be in the divalent state. The near-surface layers contain the additional oxidation forms of sulfur (S 0 , S 4+ , S 6+ ) and copper (Cu 2+ ) atoms. The detailed analysis of the valence band structure using DFT calculations has shown that partial DOS distribution character of the matrix elements is preserved after the cationic substitution. The experimental valence band spectra structure of CuCrS 2 -matrix and CuCr 0.99 Ln 0.01 S 2 is determined by the occupied copper d -states contribution. The contribution of the lanthanide states in the valence band structure is lower in comparison with those for the matrix elements. The major contribution of the lanthanide states was found to be mainly localized near the conduction band bottom.

The decomposition mechanisms of hydrated hydroxides of rare-earth metals Sm(OH)3·(H2O)gel·nH2O and Y(OH)3·(H2O)gel·nH2O, and also compound [Sm(OH)3·(H2O)gel·nH2O]q@[Y(OH)3·(H2O)gel·nH2O]p with a core–shell nanostructure were studied. In the course of the thermal treatment of hydroxides in the range of 25–900°C, stages of successive phase transformations were observed. The Avraami-Erofeev model of topochemical reactions describes the formation of phases in the systems under study with the highest correlation coefficient. The kinetics of successive dehydration and dehydroxylation of the above compounds was studied, kinetic equations of the topochemical reactions were presented, and apparent activation energies and the preexponents of the reactions were calculated. The activation energy for polycondensation of the compound with a core-shell nanostructure is lower than that of individual hydrates of samarium and yttrium hydroxides.

The temperature dependences of Seebeck coefficient, electrical conductivity (Т=300–873K), thermal conductivity and figure of merit (Т=300–770K) of polycrystalline samples of solid solutions based on gadolinium and dysprosium sulfides with γ-GdxDy1-xS1.49 (x=0.1, 0.2, 0.3, 0.4) composition were studied. It was established that samples morphological features, namely, the specific surface area of crystallites causing a change in the number of deformation centers determines the thermal conductivity of -GdxDy1-xS1.49, and it was found that there is an anomalous decrease in thermal conductivity for composition with х = 0.2. For this composition the lowest values of Seebeck coefficient -371 mkV/K at 873K, electrical resistivity 880 mkΩ∙m at 873K and thermal conductivity 0.68 ± 0.03 W/m·K at 770K were obtained, in this case the thermoelectric figure of merit reaches ZT = 0.23.

The work is devoted to the study of temperature dependences of thermal conductivity ( T = 300–770 K) of polycrystallic samples of solid solutions based on gadolinium and dysprosium sulfides of the compositions: γ -Gd x Dy 1− x S 1.49 ( x = 0.1, 0.2, 0.3, 0.4). It has been found that the morphological features of samples, namely, the specific surface area of crystallites, which causes a change in the number of deformation centers, determines the value of the thermal conductivity of γ-Gd x Dy 1− x S 1.49 solid solutions. The presence of an abnormal decrease in thermal conductivity for the composition of x = 0.2 has been established. When the temperature increases to 770 K, this anomaly decreases slightly. The minimum value of the thermal conductivity coefficient of 0.68 ± 0.03 W/(m·K) is reached for the composition under consideration at 770 K.

The study of the valence state, local environment structure and magnetic properties of novel type CuCr0.99Ln0.01S2 (Ln = La, Ce) solid solutions was carried out using X-ray absorption spectroscopy, finite difference method simulations and static magnetic susceptibility measurements. The good agreement between experimental and calculated data indicates that cationic substitution does not lead to significant changes in the copper, chromium and sulfur local environment character and electronic density distribution. The copper atoms were found to be in Cu+ oxidation state, the sulfur atoms—in S2− oxidation state and the chromium atoms—in Cr3+ state. The cationic substitution of chromium by lanthanum and cerium in CuCrS2 does not significantly affect the effective magnetic moment and exchange interactions character. The lanthanum-doped CuCr0.99Ln0.01S2 solid solution demonstrates the Seebeck coefficient value 4 times greater than for CuCrS2-matrix at 500 K.

Detection of breakdown voltage and diagnostics of the pre-breakdown state of a material is a topical task of studying the characteristics of dielectric materials and structures on their base under applied external electric field. A new efficient method for diagnosing the pre-breakdown state of multilayer structures (MLC) based on the 0.55PbMg1/3Nb2/3O3-0.45PbSc1/2Nb1/2O3 (PMN-PSN) ferroelectric relaxor is considered. The method is based on the analysis of the dynamics of the MLC surface temperature changes upon application of an external electric field. A set of MLC samples was tested under the action of an electric field E = 10 - 120 kV/cm at temperatures from room temperature to 80 ℃. The critical electric field value characterizing the pre-breakdown state and, consequently, limiting the upper level of operating voltages for electrocaloric applications, was determined for PMN-PSN multilayer structures.

Electrocaloric effect (ECE) as well as field induced pyroelectric and piezoelectric effects were investigated in relaxor ceramics 0.84 PbMg1/3Nb2/3O3–0.14 PbTiO3–0.02 SrTiO3. Dielectric and elastic properties of the solid solution were also studied. To improve the accuracy and reliability of the results obtained, the electrocaloric temperature change δT was measured both by the well-known quasi-adiabatic technique with a contact temperature sensor and by the radiometric mid Infrared technique developed by the authors. The contribution of the secondary pyroelectric effect to the total pyroelectric and ECE was studied in detail. The effect of the induced piezoelectricity on the range of the temperature stability of pyroelectric and electrocaloric responses was shown. The resulting combination of material parameters at reasonable operating temperatures and electric fields, including both the possibility of increasing δT and the existence of its temperature-independent range from 10 to 80 °C, predestines the solid solution as a promising electrocaloric material.