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We studied the dynamical spin susceptibility within the Hubbard model for hole-doped cuprates using cluster perturbation-based methods. Together with the one-electron spectral function, the two-particle response for 3 × 3 and 4 × 4 clusters are calculated and compared to each other. The results obtained are in qualitative agreement with the resonant inelastic neutron scattering and quantum Monte Carlo data. [ABSTRACT FROM AUTHOR]

The Monte Carlo method was used in a 2D model of layered HTSC to explore the dynamics of a vortex lattice in the presence of a nonuniform temperature field. Vortex configurations in a superconductor with a "thermal spot" have been found. The characteristic size of the region in which melting of the vortex lattice is observed is shown to exceed the characteristic size of the thermal spot. The possibility of directional movement of vortices by means of a temperature gradient is demonstrated in a numerical calculation. [ABSTRACT FROM AUTHOR]

The T-15MD tokamak with the warm toroidal field coils, elongated plasma cross section, and a low aspect ratio was commissioned at the National Research Center Kurchatov Institute in 2021. An economically viable fusion reactor requires long discharges or even a steady-state mode. The short pulse of the toroidal field is among the main obstacles on the way to the steady state. Therefore, as a next step after T-15MD, it is proposed at the NRC Kurchatov Institute to consider the design of a superconducting tokamak (SCT), which holds the basic geometric parameters of the T-15MD: R/a = 1.5 m/0.67 m with a field on the axis of B0 < 5 T and a long pulse of current of Ip < 5 MA. The focus of the paper is the system of the toroidal magnetic field. A three-layer design of the toroidal field coil is proposed: an inner layer of a high-temperature superconductor (HTSC), a Nb3Sn middle layer, and a NbTi outer layer. On the basis of structural strength calculations, candidate materials for coil cases were selected. For cooling the coils, a semi-longitudinal pumping of low-pressure liquid helium is proposed. The design of the HTSC cable in conduit consisting of two halves is considered in detail. A mesh cryostat design that provides a convenient access for diagnostics and plasma heating is proposed. SCT systems similar to those used in the T-15MD are analyzed. [ABSTRACT FROM AUTHOR]

Recently, the number of projects has grown connected with the application of high-temperature superconductors (HTSC) with exceptionally high current-carrying characteristics in strong magnetic fields. However, the thickness of the RBa2Cu3O7–x (R = REE, Y) superconducting layer is only 1–2% of the thickness of HTSC tape. Increasing the current-carrying characteristics owing to the thickness of the conducting layer is a promising approach. The fundamental problem of crystallite formation of a-oriented crystallites prevents the development of this approach. Such crystallites do not carry superconducting current along the substrate tape and interfere with the growth of c-oriented crystallites. This review presents existing methods of suppression of a-oriented growth, the basis of the creation of HTSC materials, and prospects of obtaining HTSC materials with high current-carrying characteristics. [ABSTRACT FROM AUTHOR]

A modified version of the use of the sol-gel process at the initial stage of the synthesis of a high-temperature superconductor Y1–xFexBa2Cu3Oy with low Fe doping is proposed. The properties of the samples obtained by sol-gel and solid-state synthesis are compared. It is shown that a more uniform distribution of the dopant throughout the volume of the sol-gel samples makes it possible to obtain materials with improved microstructural and performance characteristics. [ABSTRACT FROM AUTHOR]

Dissipation in YBCO polycrystalline bulk samples added with nominally different amounts of silver (0, 5, 15, 25 wt%) has been studied through measurements of temperature-dependent resistivity (R-T) curves in moderate magnetic fields (H ~ 0–4880 G) and correlated with the X-ray diffraction and scanning electron microscopy studies. The addition of silver has been found to modify the two-step character of resistive transition. A hump-like feature present along with the primary peak in the differential resistance vs temperature curves of pure YBCO is practically absent in the corresponding curves of YBCO/Ag composites. Ambegaokar-Halperin (AH) model of dissipation due to thermally activated phase-slip (TAPS) at Josephson junctions has been invoked to carry out a detailed scaling analysis of magneto-resistance near the critical temperature (TC) for pure and composite samples. Strikingly, in the temperature region just below TC, i.e., the region corresponding to intragranular transition, the scaling plots of inverse square root of normalized sample resistance for all four silver concentrations (0, 5 wt%, 15 wt%, 25 wt%) at all four magnetic fields (0, 0.053 T, 0.2 T, 0.4 T) approximately converge onto a universal line as predicted by the AH model. In the low-temperature intergranular transition region near TC(R = 0), the curves for pure sample exhibited a crossover from the universal line, while the curves for silver-added composites showed reasonable agreement with the universal line over almost entire transition region. Further, it has been observed that optimal doping of silver by 5 wt% and 15 wt% in YBCO enhances the value of AH barrier parameter γ (H , T) , possibly, due to improved intergranular as well as intragranular characteristics. [ABSTRACT FROM AUTHOR]

In this review, we consider the current state of development of both low-temperature superconductors based on Nb3Sn and high-temperature superconductors. The effect of the preparation method and the composition of alloying elements on the microstructure of the superconducting layer and the current-carrying capacity of superconductors based on Nb3Sn and high-temperature superconductors of the second generation based on yttrium and bismuth cuprates, magnesium diboride, and iron-containing compounds is analyzed. [ABSTRACT FROM AUTHOR]

Epitaxial YBa 2 Cu 3 O 7‒δ (YBCO) films 150–200 and 300 nm thick, respectively, were deposited on SrTiO 3 (100) substrates by pulsed laser deposition at different conditions: with and without using the velocity filtration technique. The films have T(R = 0) in the range of 77.4–87 R(T) depending on the conditions of deposition from one target with YBa 2 Cu 3 O 6.8 composition. The films contain Zn, Sr, Pd, Ag and Ti impurity elements obtained from the target (a total of no more than 2 at. %). Data of the film resistance temperature dependences, X-ray phase analysis, analysis of X-ray fluorescence (XRF) spectra and study of the surface relief by SEM methods revealed the nonuniform distributions of impurity and matrix Y, Ba, Cu elements over the film depth. Impurity concentrations near the surface lead to the formation of faceted spiral pyramids on the surface, which probably evolve into large elongated particles according to the Ostwald mechanism. This knowledge is practically important for optimizing pulsed laser deposition technologies and creating 2D instruments and devices for studying physical phenomena. • Interfaces strongly affect the elemental distribution in YBaCuO films. • Y and Cu atoms on the surface predominate at crystallite sizes greater than 200 nm. • Impurity atoms on the surface in abundance at crystallite sizes of 2–200 nm. • Impurities stimulate the surface roughness of films. • Composition modulations along the C -axis affect the superconductivity in YBCO films. [ABSTRACT FROM AUTHOR]

A very low noise figure radio frequency (RF) front-end for the cellular realm is presented. The front-end is composed of two planar YBCO high critical temperature superconductor (HTSC) bandpass filters (BPFs) and a low temperature, low noise amplifier. Using advanced HTSC growth techniques, 8-pole hairpin BPFs are implemented in a YBCO thin film grown on both sides of a sapphire substrate. The front-end is designed and implemented based on the optimal configuration of the filters derived from advanced electromagnetic simulations. Measured performance at 77 K shows a high-frequency response and very low losses, with an insertion loss of 0.15 dB and a rejection ratio of −93 dBc. The integration of HTSC filters with the low noise amplifier results in a system with superior performance, with a low noise figure of around 0.5 dB. Low insertion loss and the compact dimensions of the filter, along with low total system noise, make the designed superconducting RF front-end highly attractive for radio receivers. [ABSTRACT FROM AUTHOR]

In the actual operation of the high temperature superconducting (HTSC) maglev, due to the irregularity of the permanent magnetic guideway (PMG), the superconducting bulk always fluctuates in a small range. In order to explore this influence on the levitation force and guidance force, this paper considers that the superconducting bulk drops from the field cooling height (FCH) to the working height (WH), then maintains for a while and returns to the FCH, during the whole process of which the PMG has been subjected to the stochastic lateral and vertical excitations. Two E-J's constitutive relations are used in COMSOL Multiphysics 5.6, and compared with the model without excitations. The results show that for the levitation force, the lateral excitation mainly affects its amplitude, while the vertical excitation mainly affects its overall trend and position of the peak value. The more intense the excitation's fluctuation, the weaker the effect of the magnetic flux flow. For the guidance force, the lateral excitation mainly affects its amplitude and fluctuation's intensity, while the vertical excitation's influence is so small that can be neglected. When the superconducting bulk moves near the peak value, the effect of magnetic flux flow is particularly obvious, while near the equilibrium position, the effect is weak. On the whole, the magnetic flux flow has a distinct impact on the vertical excitation than on the lateral excitation. When without excitations, the magnetic flux flow is relatively obvious. These results reveal the rules providing the reference for the design of the HTSC maglev. [ABSTRACT FROM AUTHOR]

The engineering and technical aspects of the creation of the electromagnetic system (EMS) developed using high-temperature superconductors (HTSCs) for the TRT project (Tokamak with Reactor Technologies) are considered. Some proposals on the design of superconducting the wire and EMS windings are presented, taking into account a number of restrictions imposed by equipment and operating conditions of the TRT. A brief comparison of the TRT EMS with a number of existing projects is given. [ABSTRACT FROM AUTHOR]

We have been studying the dynamic effects of bipolar resistive switching (BERS) in memristive planar heterostructures based on c-oriented epitaxial films of the high-temperature superconductor YBa2Cu3O7 (YBCO). We have been observing the suppression of the memristive properties of the structures under sinusoidal and pulse loads and the nucleation and the evolution of the regions of current density and electric field in the structures under study. We found that the limiting frequencies of a sinusoidal type load for observing the switching effect are frequencies of about 104 Hz. It has been shown that the percolation channel is formed by the appearance of electric field domains in which the electric field threshold is reached. The switchings are controlled by two processes, with time t < ms and a longer time of the order of a few seconds. Possible physical models of the observed phenomena are being discussed. [ABSTRACT FROM AUTHOR]

The study of memristive properties or effect of resistive switchings in four classes of high-temperature superconductors (HTSC), namely Bi2Sr2CaCu2O8+y (BSCCO), YBa2Cu3O7−y (YBCO), Ba0.6K0.4BiO3−y (BKBO), and Nd2−xCexCuO4−y (NCCO), is presented. The purpose of this study is to reveal functional properties of HTSC which become apparent in the effects under discussion, prospects of usage of HTSC-based memristors in applications, and search for new mechanisms of strongly correlated nature to realize new-generation memristors (Tulina 1). The properties are as follows: undergoing the metal-insulator transition at oxygen doping, transport anisotropy, and existence of charge reservoirs through which doping of conductive copper–oxygen layers is carried out. These are the main functional properties of HTSC which allows their usage in memristors. By the example of study of bipolar effect of resistive switching in HTSC-based heterojunctions, it is shown how one can form memristor structures based on HTSC using their functional properties. [ABSTRACT FROM AUTHOR]

The fine structure of YBa2Cu3Oy single crystals with a different oxygen content subjected to a low-temperature hydrogenation have been investigated by transmission electron microscopy. It has been shown that as a result of the action of hydrogen at T = 150°С, a partial reduction of copper occurs, accompanied by the precipitation of Cu crystallites of ~100 nm in size and the formation of various structural defects. The geometric configuration of the precipitated crystallites has been considered. The results obtained show that hydrogenation is a method that makes it possible to control the structure by introducing nanosized inclusions and defects, which can be pinning centers of the magnetic vortices. [ABSTRACT FROM AUTHOR]

The effect vapors of the simplest cyclic hydrocarbons have on the structure of YBa2Cu3Oy (123) with high (у = 6.96) and low (у = 6.3) oxygen concentrations at low temperatures (200–300°C) is studied. It is found that the hydration of 123 proceeds during low-temperature treatment in vapors of these hydrocarbons. The planar packing defects form in YBa2Cu3Oy in optimum amounts along with second-phase inclusions formation as a result of the reduction of copper. The formed centers of pinning can improve the critical properties of HTSC materials in strong magnetic fields. [ABSTRACT FROM AUTHOR]

In this study, the potential possibilities of the precision of the vibrating reed method for the evaluation of the .Tc of superconducting precursors in an HTSC Bi-Pb-Sr-Cu-O system were investigated. A special technology for obtaining these samples by using solar energy for melting and following superfast melt quenching was applied to increase their internal inhomogeneity, allowing to receive high-quality textural ceramic samples of Bi1,7Pb0,3Sr2Can-1CunOy (n=2-30) showing critical temperatures of superconducting precursor transitions above bulk .Tc. To determine critical temperatures of superconducting precursors above bulk .Tc for the first time, the original vibrating reed method of studying these multiphase samples in an applied magnetic field was used. It was shown that this method has sensitivity to superconducting diamagnetism making possible to reveal new superconducting precursor phases above bulk Tc. [ABSTRACT FROM AUTHOR]

In the framework of the cluster perturbation theory for the 2D Hubbard and Hubbard-Holstein models at low hole doping, we have studied the effect of local and short-range correlations in strongly correlated systems on the anomalous features in the electronic spectrum by investigating the fine structure of quasiparticle bands. Different anomalous features of spectrum are obtained as the result of intrinsic properties of strongly correlated electron and polaron bands in the presence of short-range correlations. Particularly, features similar to the electron-like Fermi-pockets of cuprates at hole doping p ∼ 0.1 are obtained without ad hoc introducing a charge density wave order parameter within the Hubbard model in a unified manner with other known peculiarities of the pseudogap phase like Fermi-arcs, pockets, waterfalls, and kink-like features. The Fermi surface is mainly formed by dispersive quasiparticle bands with large spectral weight, formed by coherent low-energy exications. Within the Hubbard-Holstein model at moderate phonon frequencies, we show that modest values of local electron-phonon interaction are capable of introducing low-energy kink-like features and affecting the Fermi surface by hybridization of the fermionic quasiparticle bands with the Franck-Condon resonances. [ABSTRACT FROM AUTHOR]

We make use of the S = 1 pseudospin formalism to describe the charge degree of freedom in a model high- T c cuprate with the on-site Hilbert space reduced to the three effective valence centers, nominally Cu 1 + , 2 + , 3 + . Starting with a parent cuprate as an analog of the quantum paramagnet ground state and using the Schwinger boson technique, we found the pseudospin spectrum and conditions for the pseudomagnon condensation with phase transition to a superconducting state. [ABSTRACT FROM AUTHOR]

The influence of hydrogenation at T = 150°С on the structure of the YBa2Cu3Oy single crystals with different oxygen contents has been investigated using polarization optical and scanning microscopy methods with texture-orientation EBSD-analysis. It has been revealed that in the hydrogenation process on the surface of the YBa2Cu3Oy single crystals there is a partial reduction of copper with the formation of nanosized crystals of metallic copper coated with a Cu2O layer. [ABSTRACT FROM AUTHOR]

It is shown that the translation-invariant bipolaron theory of superconductivity can explain the dependence of the isotope coefficient in high-temperature superconductors on the critical temperature of a superconducting transition: in the case of strong electron–phonon interaction, the isotope coefficient is low when doping is optimal and high when it is weak. It is demonstrated that in the case of London penetration depth, the absolute value of the isotope coefficient behaves in the opposite way. A conclusion of the great role of non-adiabaticity in the case of weak doping is made. The criteria for d-wave phonon input into the isotope effect is established.

We used Raman spectroscopy to study the interaction of YBa2Cu3Oy (123) (y ≤ 6.5) with hydrogen at temperatures of 150-200°С. In contrast to the YBa2Cu3O6.96 compound, compositions with low oxygen contents show a lower tendency to form stacking faults. We found that the hydrogenation of these compositions does not lead to the transformation of the 123 phase to the pseudo-124 phase. Absorbed hydrogen does not react with oxygen in 123 and does not form hydroxyl groups. The HxYBa2Cu3Oy oxyhydride is the hydration-reaction product. [ABSTRACT FROM AUTHOR]

Abstract: Raman spectroscopy has been used to study the interactions between the YBa2Cu3O6.96 compound (123) and hydrogen at 150-200°C and their effects on the structure. It has been found that, when the YBa2Cu3O6.96 compound is subjected to hydrogen intercalation and hydration, the transformation of 123 into tetragonal phase (pseudo-124) takes place. In this case, Raman spectra of the YBa2Cu3O6.96 compound, similarly to those of a compound with absorbed water, exhibit antiferromagnetic fluctuations that are not typical of the compound. After hydrogenation, the 123 compound absorbs water under normal conditions and oxygen at temperatures below 300°C. [ABSTRACT FROM AUTHOR]

In this paper, the possibility of critical temperature increasing of superconducting precursor Tс and the current bearing capacity in samples of Bi-Pb-Sr-Ca-Cu-O superconducting system fabricated using hot shock wave consolidation (HSWC) technology and investigated by the vibrating torsional magnetometry method, was studied. The advantage of HSWC technology over the traditional technologies of superconducting composites synthesis is that the high-density materials are made from the Bi-Pb-Sr-Ca-Cu-O superconducting system. After the action of explosive wave the superconductivity is retained. After the explosion a pronounced texture is formed indicating the creation of efficient pinning centers and thus, the increase of current-carrying ability of the obtained material. The critical temperature of potential superconducting precursor Tc of transition to superconducting state increased from Tc=107K for starting sample to Tc=138K, using the HSWC technology for synthesis of samples in range of pressures from P=5GPa up to P=12GPa. [ABSTRACT FROM AUTHOR]

The influence of the double heat treatment ( T = 300 and 930°С) on the critical parameters of highly textured YBaCuO and YBaCuO ceramics has been investigated. It has been shown that, upon low-temperature annealing in humid air, planar stacking faults are formed in these ceramics. These defects are partly retained after reduction annealing (at T = 930°С) and are efficient pinning centers in magnetic fields applied parallel and perpendicular to the c axis. Due to the absorption of water, the oxygen content is increased in the ceramics, which is accompanied by an increase in the critical temperature of superconducting transition up to 94 K for YBaCuO and up to 90 K for YBaCuO. Optimal conditions of the double annealing have been established, after which the critical-current density increased to j ≥ 10 А/сm in an external magnetic field of up to 6 T. The low-temperature treatment in the neutral atmosphere saturated by water vapors deteriorates the current-carrying capacity of the highly textured ceramics, which is connected with the disappearance of texture due to the copper reduction and the precipitation of impurity phases. [ABSTRACT FROM AUTHOR]

The effect of hydrogenation at 150 and 200°С on the structure and magnetic susceptibility of YBaCuO (123) with different hydrogen contents has been studied. Upon the incorporation of hydrogen, the phase transition of the 123 phase into a defect tetragonal 124 phase occurs. In contrast to the transition upon hydration, the phase transition upon hydrogenation takes place only for compounds characterized by high oxygen contents (y > 6.5). Depending on the compound structure and oxygen content, hydrogen atoms can both occupy interstitials in Cu-O planes to form HYBaCuO and join with oxygen to form an oxide-hydroxide. In contrast to hydration, upon hydrogenation of YBaCuO, the substitution of europium for yttrium and alloying with cerium and zirconium oxides do not block the intercalation of hydrogen into the structure of the 123 compound. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effect of Gd doping on the phase formation, microstructure, transport and magnetic properties of the Bi(Pb)-2212 system. A series of superconducting bulks with a nominal composition of Bi 1.6 Pb 0.4 Sr 2 Ca 1−x Gd x Cu 2 O 8+δ with x=0, 0.05, 0.10 and 0.15 are synthesized by the solid state synthesis route. The formed samples are characterized by means of X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), electrical transport and magnetic measurements. The experiment results reveal that all the samples doped are composed of Bi-2212 phase and traces of Bi-2201 secondary phase when compared to the undoped sample. The refinement of cell parameters shows that the doping reduces the cell volume of the samples. The texture degree decreases with doping while the degree of orthorhombicity increases. Quantitative EDS analysis confirms that Gd atoms are successfully introduced into crystalline structure. The SEM micrographs show randomly distributed grains with a flake-like shape. The highest value of onset critical transition temperatures is obtained for x=0.10 and is about 90.22 K, which correlates well with the observed slope of resistivity and the hole concentration of the CuO 2 layers. Magnetic hysteresis loops suggest that the diamagnetism, remanant magnetization and lower critical field are better for x=0.10. Based on the enhancements of both grain boundary weak-links and flux pinning centers, improvement of the critical current densities and flux pinning density is obtained with this kind of doping. [ABSTRACT FROM AUTHOR]

The relaxation of high-temperature resistance, ρ(300 K t), in HoBa2Cu3O7–x single crystals after a sharp change in hydrostatic pressure is investigated. A comparison of the electrical resistance relaxation against the relaxation of the superconducting transition critical temperature Тс under the same experimental conditions points to the existence of anisotropy in vacancy cluster relaxation: cluster coalescence is dominant in the Сu–О planes; however, the generation of new clusters and coalescence of existing clusters both occur in the sample volume. [ABSTRACT FROM AUTHOR]

Charge creation in superconductor layers affects current–voltage characteristics (CVC) of the Josephson junction array and creates a breakpoint region in CVC. This charge may oscillate in the form of longitudinal plasma wave, (LPW), or nonregularity. In this paper we intend to distinguish the region with LPW from the nonregular region.

This work expands the results and derivations presented in a recent letter. It is argued that symmetry breaking Hartree-Fock (HF) solutions of a simple model of the Cu-O planes in La2CuO4, are able to describe the insulator and antiferromagnetic characters of this material. Then, this classical primer of a Mott insulator is alternatively obtained here as an exact Slater insulator within the simplest of the first principles schemes. Moreover, pseudogap HF states are also predicted. The maximal energy gap of 100 meV over the Fermi surface of this wavefunction, reasonably well matches the ARPES upper pseudogap measurements for La2CuO4 in the zero doping limit. These surprising results followed after eliminating spin and crystal symmetry constraints usually imposed on the HF orbitals. The discussion helps to clarify the role of the antiferromagnetism and pseudogaps in the physics of the HTSC materials and indicates a promising way to start conciliating the Mott and Slater pictures for the description of the transition metal oxides.

The conditions of heat transfer intensification using short local heat pulses applied to a heater cooled by fluids with a boiling curve hysteresis (cryogenic, organic fluids, and others) are considered. [ABSTRACT FROM AUTHOR]

The influence of water vapors and plastic deformation on the structure and electrophysical properties of YBaCuO (123) has been studied. It has been established that, at T = 200°C, the introduction of water into the structure of YBaCuO leads to its transition into a defect tetragonal phase of the 124 type as a result of the formation of planar stacking faults. After annealing at T = 930°C, these defects are partially retained and are efficient centers of pinning in the magnetic fields applied perpendicularly to the c axis, which makes it possible to increase (by an order of magnitude) the critical current density in the high-textured ceramics at 77 K in the external magnetic field of 5-10 T. The plastic deformation of the hydrated ceramics favors the reverse transition of the arising 124 phase to the 123 phase at T = 930°C and is accompanied by a recrystallization of the material, which leads to the appearance of a texture and an increase the critical current density. [ABSTRACT FROM AUTHOR]

Single phase polycrystalline Gd1-xPrxBa2Cu3O7-δ samples with x=0.05 , 0.10, and 0.15 have been prepared by standard solid state reaction technique and characterized by XRD and SEM analysis. The electrical resistivity, Hall effect and magnetoresistance measurements have been on the samples. The electrical resistivity measurements indicate a reduction of transition temperature (Tc) and an increase of superconducting transition width with increasing x. Hall measurements show anomalous temperature dependence for Hall coefficient (RH) in the normal state. In Gd0.90Pr0.10Ba2Cu3O7- sample, we have seen an anomalous sign reversal in the Hall coefficient with respect to temperature. The magnetoresistance measurements in the range of 0 to 10 kOe also show small changes in the normal states, although the changes are large in the superconducting state. An anomaly at 260 K appears in the transverse magnetoresistance for x=0.1 sample, which is related to the presence of magnetic Gd ion. The superconducting transition width also increases with the magnetic field in all of the samples. An exponent behavior for Hc2 versus (1-T/T0(H)) and superconducting transition width versus H have been derived. Pinning energy (U) has also been calculated from these measurements. Results show the reduction of pinning energy with the increase of magnetic field and x.Our results show that the exponent behavior of U α Hv , where v is independent of x.

In this paper, the magnetic fields end-face effect of high temperature superconducting (HTS) bulk over a permanent magnetic guideway (PMG) is researched with 3D-modeling numerical method. The electromagnetic behavior of the bulk is simulated using finite element method (FEM). The framework is formulated by the magnetic field vector method (H-method). A superconducting levitation system composed of one rectangular HTS bulk and one infinite long PMG is successfully investigated using the proposed method. The simulation results show that for finite geometrical HTS bulk, even the applied magnetic field is only distributed in - plane, the magnetic field component Hz which is along the -axis can be observed interior the HTS bulk. [ABSTRACT FROM AUTHOR]

An original two-stage liquid-phase hot explosive compaction (HEC) procedure of Mg-B precursors above 900 C provides the formation of superconductivity MgB phase in the whole volume of billets with maximal T = 38.5 K without any further sintering. The liquid-phase HEC strongly increases the solid-state reaction rate similar to photostimulation, but in this case, due to the high penetrating capability of shock waves in a whole volume of cylindrical billets and consolidation of MgB precursors near to theoretical density allows one to produce bulk, long-body cylindrical samples important for a number practical applications. [ABSTRACT FROM AUTHOR]

YBaCuO/1 wt% BSO composite thin films are grown by pulsed laser deposition. The films are irradiated with 100 KeV Ar ions at room temperature. X-ray diffraction and Raman techniques are used for analysis of structural disorder. The reduction in the intensity of the XRD peaks after irradiation gives a clue of modification occurring in the sample. Raman spectra shows the displacement of apical oxygen O(4) at 500 cm and defect induced peaks appear at 555 and 723 cm on irradiation. Field emission scanning electron microscopy (FESEM) analysis shows the agglomeration of BSO particles by damaging the surface of the film with increase in irradiation fluence. Fluctuation conductivity is analyzed within the framework of Aslamazov-Larkin and Lawrence-Doniach theories that fits well for 3D and 2D regimes. [ABSTRACT FROM AUTHOR]