Nominal Composition Bi Research Articles

Synthesis of high-temperature superconducting ceramics in the Bi(Pb)-Sr-Ca-Cu-O system based on amorphous precursors

The paper presents the results of the synthesis of bismuth superconducting ceramics with compositions Bi1.6Pb0.4Sr2Can-1CunOy (n=2, 3, 5) based on amorphous ceramics obtained by ultrafast melt quenching. In order to increase the rate of formation of superconducting compounds, effective devices have been developed for melting and hardening melts under the action of IR radiation. The sample holder was made of platinum. Melting and hardening were carried out in a continuous mode in an oxidizing environment in a flowing air atmosphere. The study of the elemental composition of the precursor samples established a slight deviation towards a decrease in the cationic composition of the precursors (Bi, Pb and Ca), relative to the stoichiometric composition. An increase in oxygen content by 12–15 % was also found. Synthesis of superconducting compounds was carried out in the temperature range of 843–850 °C, depending on the composition. The study found that in the sample Bi1.6Pb0.4Sr2Ca4Cu5Oy (2245) the superconducting high-temperature phase 2223 crystallizes. It was found that the formation of the superconducting phase 2223 in the Bi1.6Pb0.4Sr2Ca4Cu5Oy composition occurs in a lower and wider temperature range (843–848 °C) compared to the Bi1.6Pb0.4Sr2Ca2Cu3Oy (2223) composition. The complete formation of the superconducting high-temperature phase 2223 in a sample with the nominal composition Bi1.6Pb0.4Sr2Ca2Cu3Oy (2223) was carried out in a narrow temperature range of 849–850 °C, in a strict temperature regime with the participation of the liquid phase. An increase in the rate of formation of the superconducting compound 2223 in both studied compositions by 1.5–2.5 times was established, compared with the solid-phase method and other melt methods

Structural and superconducting properties of low-density Bi(Pb)-2223 superconductor: Effect of Eu2O3 nanoparticles addition

This paper presented the result of the structural analysis of Europium, Eu nanoparticles addition in low-density Bi(Pb)-2223 superconductor. Polycrystalline bulks with nominal composition Bi1.6Pb0.4Sr2Ca2Cu3Oy + xEu2O3 samples where x = 0.0, 0.2, 0.4, 0.6 and 0.8 wt% were prepared via solid-state reaction method. Low-density samples were created by adding crystalline sucrose into mixed powders and burn at 400 °C for two hours. The samples were characterized using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) for structural characterization while resistivity measurement was determined by using four-point probe method. Phase analysis by XRD indicated that both Bi-2212 and Bi-2223 phases coexist within the samples having a tetragonal crystal structure. As Eu concentration increases, the amount of Bi-2223 phase slightly decreased which signifies that Eu nanoparticles favour the growth of Bi-2212 phase. It was observed that the highest Tc and Jc values for the addition sample found at x = 0.2 wt%.

Optimising the thermoelectric properties of Bi2Sr2Co2Oy using Ag substitution and Nano-SiC doping

Bi2Sr2Co2Oy with excellent thermoelectric properties has received extensive attention from scientific researchers. In this study, Bi2Sr2Co2Oy ceramic samples were prepared using the solid-phase sintering method. By Ag + substitution for Bi3+, the hole concentration and electrical conductivity were optimised. On this basis, nano-SiC particles were introduced to increase grain boundaries, improve phonon scattering, reduce the mean free path of phonons, and reduce the lattice thermal conductivity. A sample with a nominal composition of Bi1.8Ag0.2Sr2Co2Oy + 0.025 wt% SiC had a maximum ZT value of 0.35 at 923 K, which was approximately 67 % higher than the ZT value of pure Bi2Sr2Co2Oy. These results confirmed that under the combined action of Ag substitution and SiC doping, the thermoelectric performance of Bi2Sr2Co2Oy was significantly improved.

Effects of Pb assisted cation chemistry on the superconductivity of BSCCO thin films.

Thin films of Bi-based superconductors, highly c-axis oriented, were deposited on single crystalline substrates of SrTiO3, LaAlO3, and MgO using a pulsed laser deposition technique with a Bi-2223 target of nominal composition Bi1.75Pb0.25Sr2Ca2Cu3O10±δ prepared by the solid state reaction method. The effect of different deposition parameters on the evolution of the requisite properties in the thin films has been studied. These films have been characterized by X-ray diffraction to investigate their structural properties, scanning electron microscopy to understand the effect of ex situ annealing on the grain growth, and DC resistivity measurements to quantify their superconducting critical temperature. Furthermore, the chemical states of the constituent elements Bi, Pb, Sr, Ca, Cu and O were confirmed using X-ray photoelectron spectroscopy. This information has helped in deciphering the empirical stoichiometry of the films on each of the chosen substrates. We have also been able to comment on the influence made by the choice of the substrates on the mechanism of evolution of superconductivity based on the interplay of the cation chemistry between the substituent and the constituent elements. Thin films with superior superconducting properties were obtained on SrTiO3 substrates with 58% of Bi-2223 phase fraction yielding a superconducting transition temperature (TC,offset) of 107 K. Magnetotransport studies were performed on these films to quantify their superconducting upper critical field and to comprehend the pinning mechanism.

Impact of Boron Nitride Additive on the Phase Formation and Transport Properties of Bi(Pb)-2223 Superconductor

Doping of a high-temperature Bi(Pb)-2223 superconductor with various additives, which can act as pinning centers and / or accelerate the formation of a superconducting phase, is an effective tool for obtaining Bi(Pb)-2223 samples with improved characteristics. In this paper, we studied the effect of the addition of hexagonal boron nitride (h-BN) on the phase formation and critical transport current density of ceramic samples Bi(Pb)-2223. Samples with a nominal composition of Bi1.7Pb0.3Sr2Ca2Cu3Oy [BN]x, x = 0–0.25 were prepared by the solid-phase reaction method. Two different doping methods were used: the introduction of hand-ground BN powder at the initial stage of synthesis and the addition of BN powder subjected to high-energy grinding in a ball mill before pelletizing. The phase composition of the obtained samples was studied by X-ray diffraction. The microstructure and elemental composition of the samples were studied using a scanning electron microscope with an X-ray microanalyzer. The resistivity and critical current density were measured using the standard four-probe method. The results show that boron nitride is a suitable additive to increase the rate of formation and critical transport current density Bi(Pb)-2223.

BASES OF DEVELOPMENT OF TECHNOLOGIES OF SYNTHESIS OF OXIDE MATERIALS IN BIG SOLAR FURNACE (PARKENT)

The advantages of synthesis of complex oxide compounds by solar energy, the possibility of obtaining highly textured nano materials are shown. The development of heliomaterial science, aimed at the synthesis of new materials, is inextricably linked with the use of effective optical energy systems. On the example of obtaining superconducting materials of nominal composition Bi1.7Pb0.3Sr2Ca(n-1)CunOy (n = 3-20), optimization of the parameters of the optical-energy system of the Big Solar Furnace (Parkent) is shown. The ideology of developing heliotechnology for the synthesis of inorganic materials in a solar furnace is presented. The properties of a superconducting material of nominal Bi1.7Pb0.3Sr2Ca(n1)CunOy (n = 3-20) obtained according to the proposed methodology for the synthesis of materials in a solar furnace are presented.

Ultrasound Assisted Mixing of Zinc Active Mass with Conductive Ceramic Additives for Ni-Zn Battery

Three zinc electrodes with carbon additive were prepared through ultrasound treatment. Two of them were mixed with conductive ceramic additives from the Bi-Sr-Ca-Cu-O (BSCCO) system with nominal chemical composition Bi1.7Pb0.3Sr2CuOx (B(Pb)SCCO 2201) and Bi1.7Pb0.3Sr2CaCu2Ox (B(Pb)SCCO 2212). The phase composition and morphology of the as-prepared samples were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The EDX specters suggest that the composition of the active mass does not change during the ultrasound treatment. The micrographs show that the active mass with carbon and 2201 additive has superior particle distribution compared to the other two samples.

The Investigation of Critical Temperature Tc of Homophase Superconductors Bi1.7Pb0.3Sr2Ca(n– 1)CunOy (n = 3, 4, 5) and Current–Voltage Characteristics of InP Semiconductor–Bi/Pb Superconductor (2223, 2234, 2245) Sandwich Pairs

The electrophysical properties of semiconductor–superconductor sandwich pairs (InP–Bi/Pb 2223, 2234, 2245) are investigated, in which homophase superconductors based on bismuth cuprates with high reproducible critical temperatures of superconducting transition Tc = 107–180 K are used. The advantage of melt solar technology for obtaining superconducting materials is demonstrated. The microstructure and phase composition of strongly anisotropic superconductors with nominal composition Bi1.7Pb0.3Sr2Ca(n– 1)CunOy (n = 3, 4, 5) are researched. A technique of experimental determination of superconducting transition critical temperatures Tc in single-phase and homophase HTSC samples is presented. The current–voltage characteristics of InP–Bi/Pb pairs are investigated. The relationship between the electrical resistance of sandwich pairs and superconductor critical temperature Tc is established.

Исследование критической температуры T-=SUB=-c-=/SUB=- гомофазных сверхпроводников (Bi-=SUB=-1.7-=/SUB=-Pb-=SUB=-0.3-=/SUB=-Sr-=SUB=-2-=/SUB=-Ca-=SUB=-(n-1)-=/SUB=-Cu-=SUB=-n-=/SUB=- O-=SUB=-y-=/SUB=- (n=3, 4, 5) и вольт-амперных характеристик сэндвич-пар полупроводник InP-сверхпроводник Bi/Pb (2223, 2234, 2245)

AbstractThe electrophysical properties of semiconductor–superconductor sandwich pairs (InP–Bi/Pb 2223, 2234, 2245) are investigated, in which homophase superconductors based on bismuth cuprates with high reproducible critical temperatures of superconducting transition T _ c = 107–180 K are used. The advantage of melt solar technology for obtaining superconducting materials is demonstrated. The microstructure and phase composition of strongly anisotropic superconductors with nominal composition Bi_1.7Pb_0.3Sr_2Ca_( n _– 1)Cu_ n O_ y ( n = 3, 4, 5) are researched. A technique of experimental determination of superconducting transition critical temperatures T _ c in single-phase and homophase HTSC samples is presented. The current–voltage characteristics of InP–Bi/Pb pairs are investigated. The relationship between the electrical resistance of sandwich pairs and superconductor critical temperature T _ c is established.

The microstructure characterization and phase composition analysis of (Bi,Pb)-2223 Ag/tapes with SnO, MgO and Ag2O mix-doping

The Ag/tapes with a nominal composition of Bi1.8Pb0.4Sr1.9Ca2.1Cu3.5Oy + x wt% SnO + y wt% MgO + z wt%Ag2O (x = 0, 0.2, 0.4; y = 0, 0.2; z = 0, 0.2) were prepared by sintering at 835°C for 120 h after partial–melting at 845°C for 1 h. The tape with 0.2wt%SnO, 0.2wt%MgO and 0.2wt%Ag2O mix-doping shows the highest proportion of Bi-2223 phase and the highest critical current density. A major Bi-2223 phase coexisted with a few Bi-2212 phase, and large (Sr,Ca)2CuO3, (Sr,Ca)CuO2 (∼10 µm), and fine MgO particles (∼1 µm) in the tape with 0.2 wt% SnO, 0.2 wt% MgO and 0.2 wt% Ag2O mix-doping. The Sn and Pb amount in the Bi-2223 crystals is larger than that in the Bi-2212 crystals. It suggests that the SnO in the mix-doping with Ag2O and MgO is favorable for the formation of Bi-2223 phase, and the MgO doping can increase Jc due to improving the flux pinning.

Microstructural and magneto-transport properties of Bi1.6Pb0.4Sr2Ca1−xGdxCu2O8+δ superconducting ceramics

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 Bi1.6Pb0.4Sr2Ca1−xGdxCu2O8+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 90.22K, which correlates well with the observed slope of resistivity and the hole concentration of the CuO2 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.

Solar Technology for Obtaining Superconducting Ceramic Bi1.7Pb0.3Sr2Ca(n–1)Cu n O y (n = 3 – 5) and Studying its Properties

A technology has been developed for synthesizing a superconducting ceramic from glassy-crystalline precursors having the nominal compositions (Bi1.7Pb0.3Sr2Ca(n–1)Cu n O y (n = 3 – 5). The ceramic is synthesized in a melt under the influence of solar radiation. The dependence of the formation of superconducting phases on the temperature-time conditions is studied, and the degree of texturing based on the Lotgering factor is evaluated in relation to the temperature of the ceramic’s heat treatment. The temperature at which the ceramic transitions to the superconducting state is determined (T c = 107 – 138 K) along with its post-transition stability (>7 years).

Preparation and characterization of a homemade Josephson junction prepared from a thin film sintered in a domestic microwave oven

A homemade Josephson junction was successfully obtained using a superconductor thin film of the BSCCO system. The film was deposited on a lanthanum aluminate, produced from a commercial powder with a nominal composition Bi1.8Pb0.4Sr2CaCu2Ox, was thermally treated by a domestic microwave oven. The XRD analysis of the film indicated the coexistence of Bi-2212 and Bi-2223 phases and SEM images revealed that a typical superconductor plate-like morphology was formed. From the electrical characterization, performed using DC four probes technique, it was observed an onset superconducting transition temperature measured around 81K. At the current-voltage characteristics curve, a step of electric current at zero-voltage could be observed, an indicative that the tunneling Josephson occurred.

Influences of Pb content on the critical current of Bi-2223 multi-filamentary tapes

Multifilament Bi-2223/Ag tapes with different Pb contents in precursor powders were fabricated by powder in tube (PIT) method. The influence of Pb contents on the phase formation, microstructure and critical current density of Bi-2223/Ag tapes were systematically investigated. X-ray photoelectron spectroscopy (XPS) demonstrated that the content and oxidation states change of Pb ions can influence the carrier concentration of superconducting phase. Scanning electron microscopy (SEM) revealed that the variation of Pb content can lead to the difference in microstructure due to the change of thermodynamic properties. The results showed that with the Pb content of x=0.35 in the nominal composition of Bi2−xPbxSr2Ca2Cu3Oy, proper content of liquid phase can be formed during the sintering process, thus maximum critical current (Ic) was obtained. The correlation between the transport property, carrier concentration and Pb content was discussed.

Structural and Superconducting Properties of Bi-Based Low Density HTSC<sup></sup>

Low density HTSC with nominal composition of Bi1.6Pb0.4Sr2Ca2Cu3Oy filled with crystalline sucrose has been synthesized and its structucal and superconducting properties have been studied. The transport properties, morphology, density and structural identification were determined by using the standard four point probe, Field Emission Scanning Electron Microscope (FESEM), densitometer and X-ray diffraction (XRD) respectively. The critical current density (Jc) of optimized ratio of crystalline sucrose onto Bi-2223 powder used to produce low density Bi-based superconductor was found to be higher than the bulk polycrystalline sample. TC zero obtained was varied between 93 and 101 K towards the increment ratio of crystalline sucrose with the highest TC zero = 101 K for ratio of 0.050:1.950 and decrease gradually for further addition of cystalline sucrose. The crystallographic structures was found to be remained in tetragonal where a=b≠c. The grains with higher porosity resulting in decreasing of critical current density (Jc) as well as critical temperature (Tc zero) due to lack of effective area of current flows.

Physical, magnetic and mechanical properties of Bi-2212 superconductors prepared by high pelletization pressure

In this work, ceramic superconductors with nominal composition Bi1.8Sr2Ca1.1Cu2.1Oy were produced by different pelletization pressures at high values varied from 1.5 GPa to 6 GPa. The effects of high pelletization pressure on the structural and magnetic properties of samples fabricated in this work were investigated by means of X-ray powder diffraction, scanning electron microscopy, dc electrical resistivity, magnetic hysteresis loop measurements and Vickers microhardness measurements. The room temperature resistivity of the samples significantly decreases when pelletization pressure is increased. M-H measurements were performed at T = 10 K and 25 K, respectively. In order to examine the JC characterization of samples, Bean’s critical model was used. It was found that sample D including pelletization pressures of 6 GPa have higher values of magnetization in all applied magnetic fields, indicating good connectivity between grains. Additionally, mechanical properties of samples are also characterized by microhardness measurements at room temperatures, indicating that microhardness values as well as Jc values in sample D enhanced due to its stronger couplings between grains compared to other samples.

Influence of Pb(BO2)2 Doping on Superconducting Properties of (Bi,Pb)-2223 HTS

The effect of lead borate Pb(BO2)2 doping on the phase formation and superconducting properties of (Bi,Pb)-2223 high-temperature superconductivity (HTS) has been studied. Samples with nominal composition Bi1.7Pb0.3−xSr2Ca2Cu3Oy [Pb(BO2)2]x, x = 0–0.3, were prepared by the standard solid-state processing. The appropriate mixtures were calcined at 850 °C for 30 h. The resulting materials were pressed into pellets and annealed at 840 °C for 30 h in air. X-ray diffraction, resistivity, and critical current density measurements were performed on the undoped (reference) and Pb(BO2)2-doped (Bi,Pb)-2223 compounds. The dominance of the low-Tc 2212 phase over the high-Tc 2223 phase was observed in the reference sample. With the increasing of doping level, the 2223 phase is significantly enhanced and its increase is associated with the decrease of the 2212 phase. Our results show that the sample with x = 0.075 is the best in the present study. The calculated volume fraction of (Bi,Pb)-2223 phase increases from ∼25 % for reference specimen to ∼85 % for x = 0.075 in a short sintering time (60 h). The (Bi,Pb)-2223 sample with x = 0.075 (0.15 wt% boron) reveals significant enhancement of critical current density (from 25 up to 360 A/cm2) compared to the reference sample. Obtained results could enable us to develop an accelerated and simple method for producing a high purity (Bi,Pb)-2223 superconducting materials by a proper amount of Pb(BO2)2 doping.

Effect of sintering time on Bi1.6Pb0.4Sr1.8Ba0.2Ca2Cu3O10+? compound quenched in air and liquid nitrogen

High temperature superconductor with nominal composition Bi1.6Pb0.4Sr1.8Ba0.2Ca2 Cu3O10+? was prepared by solid state reaction method. Two sets of samples have been prepared .The first one was quenched in air; the second set was quenched in liquid nitrogen. X-ray diffraction analyses showed an orthorhombic structure with two phases, high –Tc phase (2223) and low-Tc phase (2212) in addition to that impure phase was found. It has been observed that quenched in air samples display a sharp superconducting transition and a higher-Tc phase than that of the quenched in liquid nitrogen samples.

Effect of sintering time on Bi1.6Pb0.4Sr1.8Ba0.2Ca2Cu3O10+? compound quenched in air and liquid nitrogen

High temperature superconductor with nominal composition Bi1.6Pb0.4Sr1.8Ba0.2Ca2 Cu3O10+? was prepared by solid state reaction method. Two sets of samples have been prepared .The first one was quenched in air; the second set was quenched in liquid nitrogen. X-ray diffraction analyses showed an orthorhombic structure with two phases, high –Tc phase (2223) and low-Tc phase (2212) in addition to that impure phase was found. It has been observed that quenched in air samples display a sharp superconducting transition and a higher-Tc phase than that of the quenched in liquid nitrogen samples.

Effect of Different Nanosized MgO on the Transport Critical Current Density of Bi1.6Pb0.4Sr2Ca2Cu3O10 Superconductor

Magnesium oxide powders with average particle size 20 and 40 nm were added into Bi1.6Pb0.4Sr2Ca2Cu3O10 (Bi,Pb-2223) with nominal composition Bi1.6Pb0.4Sr2Ca2Cu3O10(MgO) x (x=0–0.15 wt.%). The transport critical current density (J c) and transition temperature were determined using the four-probe method. The structure and microstructure were examined by X-ray diffraction method and scanning electron microscopy, respectively. The transition temperature and J c increased with nanosized MgO addition. The 20 nm MgO added samples showed a higher J c compared with the 40 nm MgO added samples. J c was higher as size of MgO was closer to the coherence length of the superconductor. These results showed that the size variation of flux pinning center at the nanoscale is important in enhancing J c.