Ceramic samples of the ([Formula: see text])BaTiO3⋅xPbFe[Formula: see text]W[Formula: see text]O3, [Formula: see text] (([Formula: see text])BT⋅xPFW) system were synthesized by solid-state reactions method. The samples were characterized by X-ray diffraction (XRD) and dielectric studies, as well as by the measurements of the thermally stimulated depolarization currents (TSDC). It was found that the predominant phase in the samples is presented by the (Ba[Formula: see text]Pbx)(Ti[Formula: see text]Fe[Formula: see text]W[Formula: see text])O3 solid solutions with a perovskite structure, herewith the samples with [Formula: see text] are practically single-phase, and with [Formula: see text] contain the impurity phase BaWO4 (up to 15 mass.% at [Formula: see text]–0.90). Information has been obtained about the changes in the structural and dielectric characteristics of the solid solutions with the change of their composition. It is established that the solid solutions crystal lattice symmetry at 296 K changes from tetragonal at [Formula: see text] to cubic at [Formula: see text]. An increase in the PFW content in solid solutions causes a gradual change in their properties from ferroelectric at [Formula: see text] to relaxor ferroelectric at [Formula: see text], and then to properties similar to those of the dipole glass with weak or zero correlation between dipoles at [Formula: see text]. The addition of BT to PFW leads to rather quick degradation of the relaxor ferroelectric properties of PFW in the region [Formula: see text]–1.0.

Ceramic samples of the ([Formula: see text])BaTiO 3 ⋅xPbFe[Formula: see text]W[Formula: see text]O 3 , [Formula: see text] (([Formula: see text])BT⋅xPFW) system were synthesized by solid-state reactions method. The samples were characterized by X-ray diffraction (XRD) and dielectric studies, as well as by the measurements of the thermally stimulated depolarization currents (TSDC). It was found that the predominant phase in the samples is presented by the (Ba[Formula: see text]Pb x )(Ti[Formula: see text]Fe[Formula: see text]W[Formula: see text])O 3 solid solutions with a perovskite structure, herewith the samples with [Formula: see text] are practically single-phase, and with [Formula: see text] contain the impurity phase BaWO 4 (up to 15 mass.% at [Formula: see text]–0.90). Information has been obtained about the changes in the structural and dielectric characteristics of the solid solutions with the change of their composition. It is established that the solid solutions crystal lattice symmetry at 296 K changes from tetragonal at [Formula: see text] to cubic at [Formula: see text]. An increase in the PFW content in solid solutions causes a gradual change in their properties from ferroelectric at [Formula: see text] to relaxor ferroelectric at [Formula: see text], and then to properties similar to those of the dipole glass with weak or zero correlation between dipoles at [Formula: see text]. The addition of BT to PFW leads to rather quick degradation of the relaxor ferroelectric properties of PFW in the region [Formula: see text]–1.0.

Ceramic samples with compositions along the (1 – 2 x )BiScO 3 ·(2 – y ) x PbTiO 3 ∙ yx PbMg 1/3 Nb 2/3 O 3 ( y = 1.2, 1.0, 0.9, 0.5) sections in the BiScO 3 –PbTiO 3 –PbMg 1/3 Nb 2/3 O 3 (BS–PT–PMN) system have been characterized by X-ray diffraction and dielectric, piezoelectric, and thermally stimulated depolarization current measurements. The materials with 1 – x ≲ 0.5 have been shown to consist of perovskite solid solutions. With increasing BS content, the symmetry of the solid solutions rises from tetragonal to cubic. In the intermediate composition region (morphotropic region (MR)), the samples consist of a mixture of solid solutions differing in symmetry. We have located the MR boundaries and examined the effect of composition on the dielectric and piezoelectric properties of the solid solutions.

Ceramic samples with compositions along the (1 – 2x)BiScO3·(2 – y)xPbTiO3∙yxPbMg1/3Nb2/3O3 (y = 1.2, 1.0, 0.9, 0.5) sections in the BiScO3–PbTiO3–PbMg1/3Nb2/3O3 (BS–PT–PMN) system have been characterized by X-ray diffraction and dielectric, piezoelectric, and thermally stimulated depolarization current measurements. The materials with 1 – x ≲ 0.5 have been shown to consist of perovskite solid solutions. With increasing BS content, the symmetry of the solid solutions rises from tetragonal to cubic. In the intermediate composition region (morphotropic region (MR)), the samples consist of a mixture of solid solutions differing in symmetry. We have located the MR boundaries and examined the effect of composition on the dielectric and piezoelectric properties of the solid solutions.

YBa(2)Cu(3)Oy (Y-123) is one of the most intensively studied high-temperature superconductors (HTS) and has great potential for applications in electronics. Its superconducting properties significantly depend on the oxygen index (y), the peculiarities of the atomic crystal and microgranular structure, the type and concentration of contam-inating atoms. Therefore, of particular interest are the techniques of HTS synthesis that significantly affect the superconducting properties, as well as modifications of these techniques. The aim of this study was to investigate the effect of ultrahigh dilution (UHD) technology on the Y-123 HTS properties. We applied UHD technology to treat Y2O3 center dot 4BaO(2)center dot 6CuO composition (before and/or after calcination) and used solid-phase reaction to obtain batches of ceramic samples of the Y-123 phase. Main characteristics of the syn-thesized HTS specimens (the orthorhombic unit cell parameters, temperature dependence of electrical resistance, Meissner effect, and critical current density) were studied. X-ray phase analysis demonstrated that the samples were practically single-phase and consisted of the Y-123 phase. Depending on the treatment method, the modifying effect varied. Positive and most significant results were demonstrated for specimens obtained from precursor powder mixture treated with UHD. For some of such specimens an increase in the temperature of the beginning of the transition to the superconducting state by 3.8 K, the Meissner effect by 9%, and the density of the intergranular critical current by 35% were observed. We conclude that UHD technology can be used to improve properties of HTS. However, methodology for imple-mentation of UHD technology should depend on which specific superconductor property needs to be changed.

The comparative analysis of the dielectric properties of bismuth-containing pyrochlores with different manifestation of atomic order/disorder was carried out. We examined the dielectric properties (including behavior in electric fields) of two pyrochlore compounds: BZN (presumably a composition close to [Formula: see text][Formula: see text][Formula: see text][Formula: see text] ceramics with chemical disorder in both A and B cation sublattices and Bi2Ti2O7 single crystal with fully chemical ordered structure. The fundamental differences between the dielectric properties of the BZN ceramics and Bi2Ti2O7 single crystal were shown. In particular, in the dielectric relaxation behavior (which cannot be described via Arrhenius law in the Bi2Ti2[Formula: see text] or in the influence of the electric fields on the dielectric permittivity (splitting of the field-cooled and zero-field-cooled behaviors was observed for Bi2Ti2O7 below estimated freezing temperature). The results of this study highlights the special role of Bi2Ti2O7 as a candidate material for studying aspects of geometric frustration related with pyrochlore structure in non-magnetic medium and specifies the future directions of research.

— (1 – x )Ba(Ti 0.75 Sn 0.25 )O 3 ∙ x PbTiO 3 (0 ≤ x ≤ 1) samples prepared by a standard ceramic processing route have been characterized by X-ray diffraction, thermogravimetry, and dielectric, piezoelectric, and pyroelectric measurements. The results demonstrate that the system in question contains solid solutions with the perovskite structure, which have cubic symmetry for x < 0.2 and tetragonal symmetry for x ≥ 0.2. Increasing the percentage of PbTiO 3 in the samples has been shown to cause sequential changes in their dielectric properties in the following sequence: ferroelectric relaxor, reentrant ferroelectric relaxor, ferroelectric with a diffuse phase transition, and conventional ferroelectric.

Bi-based layer structure ferroelectrics are the most promising compounds for the fabrication of high-temperature piezoelectric materials. Studies aiming to develop and optimize the techniques to produce efficient high-density piezoelectric ceramics, and to investigate the effects of ceramics production conditions on their structure and functional properties, have become high-priority objectives of modern piezo-engineering. We applied ultra high dilution (UHD) technology to pre-treat Bi3TiNbO9 powders and used hot pressing to prepare perovskite-layer structured ceramic specimens. Main characteristics of the synthesized piezoelectric ceramic specimens (the dimensions of the Bi3TiNbO9 orthorhombic unit cell, dielectric permittivity, dielectric loss, piezoelectric coefficient d33 and pyroelectric coefficient pσ) and their temperature-dependent variations were studied using piezoelectric, dielectric, and pyroelectric measurements. X-ray diffraction studies demonstrated that the prepared ceramics were single phased, and highly textured, as their plate-like crystallites were preferentially aligned perpendicularly to the pressure axis on hot pressing. For d33, an increase in values of more than 20% was found for samples obtained using a combined modification of the UHD technology and hot pressing (12 pC/N) relative to intact samples, and more than two times relative to unmodified Bi3TiNbO9 ceramics (6 pC/N). Due to their characteristics, the obtained ceramics are promising materials for high-temperature applications; of particular interest is potential use, as electroacoustic transducers and sensors for operation at high temperatures. Thus, the UHD technology can modify the properties of ceramics and is relatively easy to implement. This makes it attractive for use in various fields of science and technology.

(1 – x)Ba(Ti0.75Sn0.25)O3 ∙ xPbTiO3 (0 ≤ x ≤ 1) samples prepared by a standard ceramic processing route have been characterized by X-ray diffraction, thermogravimetry, and dielectric, piezoelectric, and pyroelectric measurements. The results demonstrate that the system in question contains solid solutions with the perovskite structure, which have cubic symmetry for x < 0.2 and tetragonal symmetry for x ≥ 0.2. Increasing the percentage of PbTiO3 in the samples has been shown to cause sequential changes in their dielectric properties in the following sequence: ferroelectric relaxor, reentrant ferroelectric relaxor, ferroelectric with a diffuse phase transition, and conventional ferroelectric.

Large impurity-free Bi2Ti2O7 single crystals were grown by slow cooling of a melt. Their crystal structure and dielectric properties as a function of temperature at different frequencies were studied for the first time. A step-like frequency-dependent anomaly was observed at a temperature of about 220 K at a frequency of 1 kHz. The relaxation behavior is well described by the empirical Vogel-Fulcher relation typical for relaxor ferroelectrics. Based on the value of fitting parameters, Bi2Ti2O7 occupies an intermediate position between the canonical relaxor PbMg1/3Nb2/3O3 on the one hand and lead-free relaxors based on BaTiO3 on the other hand. The possible mechanisms of the observed dielectric relaxation of the Bi2Ti2O7 single crystals are discussed.

Designing magnetic systems of Galathea plasma traps on the basis of levitating superconducting magnetic coils requires searching for their stable levitating states. For this purpose, proceeding from the property of superconductors to preserve the trapped magnetic flux, the potential energy of a system of several coaxial superconducting rings (one of the rings is fixed) with given trapped magnetic fluxes is obtained as an analytic function of the coordinates of the free rings along the system axis and angular deviations of their axes from the common axis of the system in a uniform gravity field in the thin-ring approximation. Computations demonstrate that, under certain values of physical parameters (the trapped magnetic flux and the dimensions and masses of the rings), this dependence has local minima, which correspond to stable equilibrium states of the levitating rings. For high-temperature superconducting (HTSC) rings and short-circuited HTSC coils manufactured for experiments on levitation, equilibrium states are found in different cases by calculating the aforementioned dependence of the potential energy. In the case where the magnetic fluxes trapped by the rings have the same signs, the calculated equilibrium levitating states of an HTSC ring in the field of a short-circuited HTSC coil (or an HTSC ring), namely, states that are stable against vertical displacements and angular deviations of the axis from the vertical, are implemented experimentally.

— Platelike LiCu 3 O 3 single crystals up to 2 × 8 × 8 mm in dimensions have been grown by slowly cooling (1 – x )Li 2 O ∙ x CuO ( x = 0.88–0.92) melts and characterized by thermogravimetry and electrical measurements. We have determined the temperature stability range of LiCu 3 O 3 (750 to ~1000°C) and measured the dc and ac (0.1–100 kHz) resistivity of the crystals as a function of temperature in the temperature range 10–295 K. The results demonstrate that, in the temperature range 45–295 K, the conduction mechanism in LiCu 3 O 3 crystals is hopping between nearest neighbors with the participation of small polarons and that the electrical conductivity of the crystals is a nonlinear function of electric field.

Multilayer piezo stack based on Na0,5Bi4,5Ti4O15 was produced by tape casting slurry technology. X-ray diffraction, dielectric permittivity, piezoelectric and pyroelectric studies have been performed on the specimens. It was established that specimens have a textured structure due to the orientation of basal planes (001) plate-like grains parallel to the direction of film casting. The Curie point (T-c = 645 degrees C) of the obtained stacks have been determined from the temperature-frequency dependences of the dielectric permittivity and loss tangent, it is established that they have a relatively high effective piezoelectric constant (d(33)*= 180 pC/N) for NBT based ceramic system. In concluding it has been analyzed the prospect of the specimens in high temperature applications.

Ceramic samples of the (1-2x)BiScO3-xPbTiO3-xPbMg1/3Nb2/3O3 system in the whole compositions region x = 0-0.50 were synthesized. According to the X-ray diffraction studies (XRD), the region of solid solutions with perovskite structure formation in the system was determined (x = 0.23-0.50). The presence of a morphotropic phase boundary between tetragonal and rhombohedral forms of solid solutions was established at x = 0.40-0.42. Refined XRD with profile peak analysis established the presence of the additional cubic phase with broadened X-ray reflexes in the solid solutions along with the main phase. It was concluded that the main and additional phases are located in the volume and in the surface layer of ceramic crystallites, respectively. The crystal structures of phases in the polarized and depolarized sample with x = 0.42 were determined by the Rietveld method. It was found that the monoclinic perovskite phase is present in the polarized sample. Temperature-frequency dependences of dielectric permittivity and losses of solid solutions were studied. It was found that the increasing content of BiScO3 in samples causes a change in their dielectric properties from the usual ferroelectric (FE) in the region (1-2x) = 0-0.08 to ferroelectric-relaxor (FE-R) in the region (1-2x) = 0.08-0.40, and then to the properties of dipole glass with weak correlations in the region (1-2x) > 0.40. It was found that the samples with x = 0.434 and 0.446 below Tc = 414 and 445 K spontaneously pass to the FE state. In the samples with x = 0.42 the application of an electric field of 2.0 kV/ cm induces a transition from FE-R to FE state with Tc = 350 K, which remains after the field is removed.