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In this study, MgB 2 polycrystals were synthesized via the addition of B 4 C and Dy 2 O 3. X-ray diffraction confirmed that MgB 2 was the predominant phase in all the samples. The superconducting properties of the samples were characterized by in-field temperature-dependent resistivity and magnetization measurements. The upper critical field (H c2) and the critical current density (J c) of each sample were estimated. The results indicate significant enhancements in H c2 and J c with the optimal addition levels of B 4 C and Dy 2 O 3. According to collective pinning theory, δl pinning was identified as the dominant pinning type in the fabricated samples. The dominant pinning mechanism was determined to be core surface pinning induced by grain boundaries, which is consistent with predictions made by the Dew–Hughes model. [ABSTRACT FROM AUTHOR]

To explore the possibility of improving the critical current density (J c) of polycrystalline La 1.84 Sr 0.16 CuO 4 (LSCO) superconductor ceramics, high density La 1.84 Sr 0.16 CuO 4 samples have been prepared by means of spark plasma sintering (SPS). Structural and superconducting properties of samples made by different variations of the process have been measured for systematic comparison. The density of the SPS samples can reach up to 98 % of the theoretical density of LSCO, but the critical temperature (T c) and critical current density (J c) are suppressed by the process. Subsequent annealing has been applied to improve the properties of the SPS samples. After treatment at 1050 °C, in spite of partial decomposition that was observed on the surface of the samples, the J c of LSCO was significantly improved. Detailed data as well as assumptions for explaining these results are provided. The SPS technique, coupled with a suitable post-annealing treatment is thereby appearing as a possible methodology to improve the critical current density of polycrystalline high temperature cuprate superconductors. [ABSTRACT FROM AUTHOR]

The flexible Li‐ion conducting solid polymer electrolyte (SPE) endows a stable long‐term cycling to Li‐metal anode to significantly improve the energy density of solid‐state lithium batteries; however, the practical application of the SPE is limited by its low ionic conductivity and small critical current density for dendrite nucleation. Herein, Li+‐doped porous ZnO (LZO) nanosheets are introduced into the poly(ethylene oxide) (PEO)‐based SPE, releasing more mobile Li ions for faster Li‐ion transport due to the enhanced interaction between abundant oxygen vacancies and anions of Li‐salt. As a result, the optimized LZO/PEO composite polymer electrolyte exhibits a high Li‐ion conductivity of 3.3 × 10−4 S cm−1 at 50 °C, 4 times higher than the pure PEO electrolyte. The solid‐state LiFePO4/Li cell shows extraordinarily long‐term stable cycling, up to 1500 cycles with a high average Coulombic efficiency of 99.8%. In addition, the cycling stability of the high‐voltage LiNi0.8Mn0.1Co0.1O2 (NMC811)/Li cell was also obviously improved compared to the nondoped pure PEO electrolyte, indicating the positive contribution of the LZO on interfacial stability. [ABSTRACT FROM AUTHOR]

The proton exchange membrane water electrolyzer (PEMWE) is one of the most promising electrochemical energy conversion devices for hydrogen production, while still limited by performance bottlenecks at high current densities, due to the lack of mass transfer insights. To investigate the mechanisms of oxygen transport inside the PEMWE at high current density and its relation to electrolytic performance. Operational in situ x‐ray imaging is utilized to simultaneously characterize the bubble behavior and voltage response in a novel designed visual mini‐cell, and it is identified that oxygen evolution and transport in the PEMWE follow the process of bubble nucleation, growth, and detachment. Based on the results of mini‐cells with three porous transport layers (PTLs) up to 9 A cm−2 operation, it revealed that critical current densities exist for both carbon‐based and titanium‐based PTLs. Once exceeding the critical current density, the cell voltage can no longer be stabilized and the cell exhibits a significant oxygen overpotential. To illustrate this, the concept of interfacial separation zone (ISZ) is first proposed, which is an effective pathway for bubble growth and separation and the pattern of the ISZ exhibits specific regimes with the critical current density. Ultimately, a new approach for better understanding the mechanisms of oxygen transport is revealed. [ABSTRACT FROM AUTHOR]

High magnetic fields play a crucial role in advancing basic sciences, fusion energy, and magnetic resonance imaging systems. However, the widespread use of high-field magnets requires affordable high-temperature superconducting wires that can carry large supercurrents. Iron-based superconductors offer an economically attractive solution to push forward important yet costly scientific programs, such as nuclear fusion reactors and next-generation particle accelerators. In this review, we start with the fabrication of iron-based superconducting wires and tapes and continue to discuss several key factors governing the current transport properties. State-of-the-art wires and tapes are introduced with emphasis on grain boundary characteristics, flux pinning, and anisotropy. The architecture of flexible conductors enables low cost, high mechanical strength, and high thermal stability. Recent progress in practical applications, including superconducting joints and insert coils, is also reviewed. Finally, we propose several key questions faced by iron-based superconductors in future practical applications. [ABSTRACT FROM AUTHOR]

Our results enable a better understanding and explanation of the physical phenomena associated with strong trapping of vortex lattice in superconducting wires. These measurements showed that dislocations oriented perpendicular to the external magnetic field most strongly trapped the vortex lattice in 8 T and much weaker in the 6 T magnetic field. Further research showed that dislocations situated in the angle of 45° to the external magnetic field most strongly trap the vortexes lattice in 7 T magnetic field. Subsequent results showed that dislocations oriented parallel to the external magnetic field trap the vortex lattice most strongly in the 6 T magnetic field and much weaker in the 8 T magnetic field. Previous studies have not reported these results and pinning analyses. Our results are also important for pinning centers created by irradiation for columnar defects. [ABSTRACT FROM AUTHOR]

V- Ti alloys are promising alternatives to Nb for the construction of superconducting solenoids that produce high magnetic fields. The critical current density ( J C ), which quantifies the capacity of a superconductor to carry large dissipationless current, increases in the V-Ti alloys with the addition of Ce. Here, the effects of successive cold working and annealing on the electrical resistivity, J C , and microstructure of the V 0.59 Ti 0.40 Ce 0.01 alloy are studied. The J C is the maximum after the second cold rolling. Annealing at 650 ∘ C is found to nucleate and grow the α -phase which is detrimental to J C , whereas the precipitation of the α ′ -phase is found to improve the J C . [ABSTRACT FROM AUTHOR]

The second generation (2G) high-temperature superconducting (HTS) REBCO tape and the HTS cable made by the REBCO company are considered to be alternative materials for future superconducting magnet design due to their exceptional performance. The twisted stacked-tape slotted-core (TSSC) cable-in-conduit-conductor cable, which is one of the crucial layout structures in HTS cables, has been extensively studied by numerous research groups over the years. In this paper, a 3D finite element model of the TSSC HTS cable under bending and axial tensile loads is established using the bilinear isotropic hardening model in COMSOL commercial finite element software. The mechanical behavior of the TSSC cable under bending and axial tensile loads, as well as the evolution process of overall cable performance and critical current of individual tapes inside slots, are revealed by conducting mechanical analysis and using an empirical fitting formula between the critical current density of the 2G HTS tapes and axial strain. Furthermore, optimization engineering suggestions for its structure are provided, such as reducing the twist pitch, decreasing the tape width, increasing the number of tapes, reducing the slot width while avoiding direct contact between tapes and slot walls, increasing the number of slots, increasing diameter of diversion trench and inner diameter of helical core under predominant bending loads. In the case of axial tensile loads, the aforementioned suggestions are also applicable except for the inner and outer diameters of the helical core. The critical current performance can be enhanced by augmenting the outer diameter of the helical core in this case. However, it is almost unaffected by the inner diameter of the helical core. [ABSTRACT FROM AUTHOR]

A systematic investigation has been performed by synthesis and comprehensive characterization of a series of SmFe1−xCuxAsO0.8F0.2 bulks (x = 0–0.2). These samples are well characterized by structural, Raman spectroscopy, microstructural, transport, magnetic measurements, and supplementary calculations within density functional theory (DFT). The parent compound, SmFeAsO0.8F0.2 (Sm1111), exhibits a superconducting transition temperature (Tc) of approximately 54 K. The lattice volume (V) is increased with Cu substitution (x) without observing any impurity phase related to copper, which confirms the successful incorporation of Cu at Fe sites in the superconducting FeAs layers. These analyses are also well in agreement with Raman spectroscopy measurements and relevant DFT results. The superconducting transition is decreased systematically with copper doping and completely suppressed for 7% Cu‐doped Sm1111 (x = 0.07). A large amount of Cu substitution (x ≥ 0.07) has demonstrated the metal to insulate transition in the low‐temperature range, and no impurity phase was observed even at high Cu doping levels (x = 0.2). The calculated critical current density of the parent sample is suppressed with copper substitution, suggesting the reduced pinning centers, sample density, and grain connections, as confirmed by the microstructural analysis. Our studies suggest that the substitution of Cu in the superconducting FeAs layer, resulting the enlargement of the lattice volume, is a source of strong disorder scattering, leading to the suppression of Tc and the emergence of metal‐to‐insulator, unlike the more successful carrier doping by nickel (Ni) or cobalt (Co), as previously reported. [ABSTRACT FROM AUTHOR]

In this study, we present the fabrication of large single-domain ternary (Sm,Eu,Gd)Ba 2 Cu 3 O 7-y bulk superconductor with enhanced superconducting properties using various REBa 2 Cu 3 O y (RE-123) as a liquid source via the top-seeded infiltration growth process (TSIG) in air. We employed a 1:1 ratio of REBa 2 Cu 3 O y (RE = Sm, Gd, Y and Er) and Ba 3 Cu 5 O 8 as a liquid source for fabrication. Impressively, all the obtained bulk samples exhibited a superconducting transition temperature T (c, onset) above 94 K. However, the bulk sample fabricated using Y-123 + Ba 3 Cu 5 O 8 as a liquid source demonstrated a T (c, onset) of 94.53 K, with a 40.14 % improvement in transition width (Δ T c) and at 77 K the bulk recorded a self-field critical current density (J c) value of 44.73 kA/cm2 & 10.62 kA/cm2 at 1T resulting in a remarkable 93.08 % improvement in self-field J c compared to the bulk sample fabricated using Er-123 + Ba 3 Cu 5 O 8. Microstructural analysis using a scanning electron microscope revealed a significant reduction in the mean size of secondary (211) phase particles, a significant reduction of 38.41 % is observed for the Y-123 + Ba 3 Cu 5 O 8 employed sample. [ABSTRACT FROM AUTHOR]

Uneven distribution of local superconducting properties can significantly impact the overall performance of REBa2Cu3O7-δ (REBCO or RE123) superconductor bulks. Through the modified top-seeded melt-texture growth method, we successfully prepared single-domain GdBa2Cu3O7-δ (GdBCO) superconductor bulks with (bulk A) and without (bulk B) a buffer layer, and investigated the relationship between superconducting properties and microstructure of the bulks in detail. Measurement results show that the maximum trapped flux density value of bulk A is 0.48 T, and that of bulk B is 0.5 T. The distribution of transition temperature (TC) and critical current density (JC) becomes more uniform along the c- and a/b-directions in bulk A. In bulk B, i.e., without a buffer layer, the JC varies greatly at different locations due to microstructural inhomogeneity. The buffer layer acting as a large seed can increase the growth rate, resulting in a decrease in the size and an increase in the concentration of Gd2BaCuO5 (Gd211) particles in the microstructure according to pushing/trapping and coarsening theory. The corresponding JC performance shows a certain improvement in all fields, which suggests that the buffer layer has a positive effect on the spatial uniformity of superconducting properties in superconductor bulks. [ABSTRACT FROM AUTHOR]

Information on the state of research on the effect of hydrogen on the superconducting properties of various compounds is presented. The review consists of an introduction, one appendix and four sections: methods for the synthesis of modern hydrogen-containing superconductors, experimental studies of the properties of hydrogen-containing superconductors, mechanisms of the influence of hydrogen on superconductivity, problems and prospects of hydrogen-containing superconductors. [ABSTRACT FROM AUTHOR]

Inter-granular Sn particles affect transport and magnetic properties both in the normal and superconducting states of polycrystalline GdBa2Cu3O7−δ (GdBCO) superconductors drastically. Normal state resistivity at 300 K increases ~ 18.0 times as the concentration of Sn is increased. An unusual upturn in resistivity as a function of temperature curve with a dip is observed in GdBCO with 3.0 wt% of Sn in which suppression of superconducting phase transition has been observed. Current-voltage (IV) curves below Tc exhibit nonlinear features in composites of GdBCO and Sn. Magnetization (M) as a function of magnetic field (H) curves at 2.0 –20.0 K in GdBCO shifts strongly with the addition of 1.0 wt% Sn. We have extracted irreversible magnetization, lower critical field (Hc1) and magnetic critical density (Jcm) as a function of H at several T. The maximum pinning force density is 0.4 GN/m3 in GdBCO which is reduced in the Sn added GdBCO. [ABSTRACT FROM AUTHOR]

The flexible Li‐ion conducting solid polymer electrolyte (SPE) endows a stable long‐term cycling to Li‐metal anode to significantly improve the energy density of solid‐state lithium batteries; however, the practical application of the SPE is limited by its low ionic conductivity and small critical current density for dendrite nucleation. Herein, Li+‐doped porous ZnO (LZO) nanosheets are introduced into the poly(ethylene oxide) (PEO)‐based SPE, releasing more mobile Li ions for faster Li‐ion transport due to the enhanced interaction between abundant oxygen vacancies and anions of Li‐salt. As a result, the optimized LZO/PEO composite polymer electrolyte exhibits a high Li‐ion conductivity of 3.3 × 10−4 S cm−1 at 50 °C, 4 times higher than the pure PEO electrolyte. The solid‐state LiFePO4/Li cell shows extraordinarily long‐term stable cycling, up to 1500 cycles with a high average Coulombic efficiency of 99.8%. In addition, the cycling stability of the high‐voltage LiNi0.8Mn0.1Co0.1O2 (NMC811)/Li cell was also obviously improved compared to the nondoped pure PEO electrolyte, indicating the positive contribution of the LZO on interfacial stability.

Abstract The proton exchange membrane water electrolyzer (PEMWE) is one of the most promising electrochemical energy conversion devices for hydrogen production, while still limited by performance bottlenecks at high current densities, due to the lack of mass transfer insights. To investigate the mechanisms of oxygen transport inside the PEMWE at high current density and its relation to electrolytic performance. Operational in situ x‐ray imaging is utilized to simultaneously characterize the bubble behavior and voltage response in a novel designed visual mini‐cell, and it is identified that oxygen evolution and transport in the PEMWE follow the process of bubble nucleation, growth, and detachment. Based on the results of mini‐cells with three porous transport layers (PTLs) up to 9 A cm−2 operation, it revealed that critical current densities exist for both carbon‐based and titanium‐based PTLs. Once exceeding the critical current density, the cell voltage can no longer be stabilized and the cell exhibits a significant oxygen overpotential. To illustrate this, the concept of interfacial separation zone (ISZ) is first proposed, which is an effective pathway for bubble growth and separation and the pattern of the ISZ exhibits specific regimes with the critical current density. Ultimately, a new approach for better understanding the mechanisms of oxygen transport is revealed.

The macroscopic electromagnetic properties of type-II superconductors are mainly influenced by the behavior of microscopic superconducting flux quantum units. Time-dependent Ginzburg-Landau (TDGL) theory is a well-known tool for describing and examining both the statics and dynamics of these superconducting entities. It have been instrumental in replicating and elucidating numerous experimental results over the past decades. This paper provides a comprehensive overview of the progress in TDGL simulations, focusing on three key aspects of superconductor applications. We delve first into vortex rectification in superconductors described within the TDGL framework, specifically highlighting the achievement of superconducting diode effect through asymmetric pinning landscapes and the reversible manipulation of vortex ratchets with dynamic pinning landscapes. In terms of the achievements of TDGL simulations concerning the critical current density of superconductors, we emphasize particularly on the optimization of pinning sites, including vortex pinning and dynamics in polycrystalline Nb3Sn with grain boundaries. In the third aspect, we concentrate on numerical modeling of vortex penetration and dynamics in superconducting radio-frequency cavities, including a discussion on superconductor-insulator-superconductor multilayer structures. Finally, we present key findings, insights, and perspectives derived from the discussed simulations.

MgB2 bulks were synthesized by the Mg diffusion method under exactly the same conditions, using B powder of three different purities purified in Turkey. In laboratory scale studies, high purity starting powders are used. For large-scale production, low purity powders are better in terms of production costs. In this study, the effect of low purity grade B on the Mg diffusion method was examined. The microstructural properties of MgB2 samples produced by heat treatment at 850 °C for 10 hours were examined by XRD analysis. Rietveld refinement was performed on these results, and lattice parameters were obtained around a=b=3.08 Å, c=3.52 Å. Crystal sizes and microstrains were calculated using the Scherrer and Williamson-Hall formulas. In addition, by magnetic measurements, the Tc was determined to be 38.74 K, and the Jc (B = 0) at 20 K was determined to be 3.14'105 A/cm2 for the sample using an 86.70% purity B source. Fp was calculated, and pinning mechanisms were examined using the Dew-Hughes scaling approach. The dominant pinning mechanism was determined to be grain boundaries and non-superconducting points. It has been shown that high Jc and Tc values, which are important for relevant technologies, can be achieved with the 86.70% purity of the B source purified in Turkey. [ABSTRACT FROM AUTHOR]

We investigated the impact of annealing on the structural characteristics and superconducting critical temperature ( T c ) of the eutectic high-entropy alloy (HEA) superconductor NbScTiZr. The HEA manifests an eutectic microstructure composed of body-centered cubic (bcc) and hexagonal close-packed phases. Both the lattice parameters of the bcc phase and grain size of the eutectic structure exhibited pronounced sensitivity to variations in annealing temperature. The observed dependence of the lattice parameter on annealing temperature supports the possibility that lattice strain occurs at lower annealing temperatures. The as-cast sample demonstrated superconductivity at T c of 7.9 K, which increased to 9 K after annealing at 800 ∘ C. However, when subjected to annealing at 1000 ∘ C, T c diminishes to 8.7 K. The annealing temperature dependence of T c cannot be comprehensively elucidated based solely on the electronic density of states at the Fermi level. It is plausible that the lattice strain may influence the annealing temperature dependence of T c . Our results for the critical current density J c reveal that the self-field J c of the as-cast NbScTiZr at 2 K exceeds 10 6 A/cm 2 . [ABSTRACT FROM AUTHOR]

All‐solid‐state lithium metal batteries (ASSLMBs) with solid electrolytes (SEs) have emerged as a promising alternative to liquid electrolyte‐based Li‐ion batteries due to their higher energy density and safety. However, since ASSLMBs lack the wetting properties of liquid electrolytes, they require stacking pressure to prevent contact loss between electrodes and SEs. Though previous studies showed that stacking pressure could impact certain performance aspects, a comprehensive investigation into the effects of stacking pressure has not been conducted. To address this gap, we utilized the Li6PS5Cl solid electrolyte as a reference and investigated the effects of stacking pressures on the performance of SEs and ASSLMBs. We also developed models to explain the underlying origin of these effects and predict battery performance, such as ionic conductivity and critical current density. Our results demonstrated that an appropriate stacking pressure is necessary to achieve optimal performance, and each step of applying pressure requires a specific pressure value. These findings can help explain discrepancies in the literature and provide guidance to establish standardized testing conditions and reporting benchmarks for ASSLMBs. Overall, this study contributes to the understanding of the impact of stacking pressure on the performance of ASSLMBs and highlights the importance of careful pressure optimization for optimal battery performance. [ABSTRACT FROM AUTHOR]

Iron-based superconductors are under study for their potential for high-field applications due to their excellent superconducting properties such as low structural anisotropy, large upper critical fields and low field dependence of the critical current density. Between them, Fe(Se,Te) is simple to be synthesized and can be fabricated as a coated conductor through laser ablation on simple metallic templates. In order to make all the steps simple and fast, we have applied the spark plasma sintering technique to synthesize bulk Fe(Se,Te) to obtain quite dense polycrystals in a very short time. The resulting polycrystals are very well connected and show excellent superconducting properties, with a critical temperature onset of about 16 K. In addition, when used as targets for pulsed laser ablation, good thin films are obtained with a critical current density above 105 A cm−2 up to 16 T. [ABSTRACT FROM AUTHOR]

Featured Application: This work concerns the study of the granular nature of an YBa2Cu3O7-x superconducting film, whose expertise can be useful in understanding the temperature and the DC and AC field application ranges of these materials with non-optimized fabrication properties, which are typically found in superconducting wires and power cables. The study of granularity in superconducting films by using AC susceptibility has a crucial role in the development of and improvement in the ReBCO-coated conductors, which are a constantly evolving reality in the modern power applications of superconductivity. Specifically, the study of the granularity is essential because the ReBCO superconducting wires and tapes are far from the regularity of a single crystal while they often present an inter- and intragranular contribution to the critical current density. On the other hand, the AC susceptibility is a key part of the characterization of a granular sample because this technique is very sensitive to the presence of granularity in the superconductors and, moreover, the study of its first harmonic allows for determining pivotal properties such as the pinning energy as well as the dissipation processes acting in the sample. The pinning energy values and the granularity of an YBCO thin film have been studied by means of AC susceptibility measurements as a function of the AC amplitude, temperature, and DC field. In particular, the first harmonic imaginary component of the AC susceptibility χ 1 ″ related to the dissipation processes of the sample has been studied. First, starting from the Brandt approach, the critical current density Jc and the pinning energy U of the sample have been extracted at 77 K by using the χ 1 ″ measurements as a function of the AC amplitude at different AC frequencies and DC fields. From these measurements, a first signal of granularity appears. In order to confirm it, the temperature dependence of the χ 1 ″ at different DC fields has been studied and a contribution deriving from the inter- and intragranular part of the sample has emerged. By taking the temperature corresponding to the crossover between the two contributions at the different DC fields, the intergranular and intragranular response has been separated. Successively, the temperature has been fixed to 77 K, together with an AC frequency equal to 1597.9 Hz, and the χ 1 ″ as a function of the DC field at different AC amplitudes has been analyzed showing a clear presence of granularity in all the curves. By drawing the contour plot of the χ 1 ″ with the DC and AC values, it was possible to determine the best parameters to put at 77 K in order to exploit the material for applications. [ABSTRACT FROM AUTHOR]

Given their excellent superconducting properties, REBa2Cu3Oy (REBCO)-coated conductors (CCs) are anticipated to be utilized in a variety of magnet applications. To further increase the critical current density J c of these materials to levels needed for commercial applications, this study employs reel-to-reel (RTR) pulsed laser deposition (PLD) to fabricate REBCO+BaHfO3 (BHO) CCs. PLD creates BHO nanorods, which serve as flux-pinning defects. The material is subjected to O2+ irradiation to introduce more defects. The irradiation-induced defects serve as flux-pinning centers to the REBCO+BHO-nanorod CCs, increasing J c along the c axis and over a wide range of magnetic-field angles compared with conventional REBCO+BHO-nanorod CCs. Both nanorods and irradiation-induced defects are demonstrated to be effective pinning centers in this material. [ABSTRACT FROM AUTHOR]

We investigated the effect of Fe 50 Pd 50 nanoparticle addition on the crystal structure and superconductivity of Bi 1. 6 Pb 0. 4 Sr 2 Ca 2 Cu 3 O 10+δ compounds. Pure and Fe 50 Pd 50 -added Bi 1. 6 Pb 0. 4 Sr 2 Ca 2 Cu 3 O 10+δ samples with different additional contents were prepared by the solid-state reaction technique. Crystal structure and surface morphology of the fabricated samples revealed the formation of Bi-2223 and Bi-2212 superconducting phases. The critical temperature (T c) of the Fe 50 Pd 50 -added samples was lower than that of the pure one. In comparison with the pure sample, magnetization J c was clearly enhanced for the samples with the addition of Fe 50 Pd 50 having stronger magnetic properties. The enhancement in J c was possibly explained by the fact that Fe 50 Pd 50 nanoparticles served as effective pinning centers. Dominant pinning mechanisms of all samples were analyzed to be δl pinning by the collective pinning theory. The geometry of artificial pinning centers was identified to be normal core volume and point-like pinning by using the Dew–Hughes model. [ABSTRACT FROM AUTHOR]

This study examined the impact of adding hard ferrite Ba0.5Sr0.5Fe12O19 (BSF) nanoparticles to the Bi1.8Pb0.4Sr2Ca2Cu3.2O10+δ (Bi, Pb)-2223) superconductor phase. The investigation specifically focused on evaluating the critical current density, fluctuation-induced conductivity, and magnetoresistance of nano-(BSF)x/(Bi, Pb)-2223 composite, where 0.00 ≤ x ≤ 0.20 wt.%. The results revealed that the critical current density, Jc, increased with the addition of nano-(BSF) up to x = 0.04 wt.%, reaching a value of 441.20 A/cm2. The Aslamazov and Larkin (A–L) approach has been evaluated the fluctuation-induced conductivity. Several superconducting parameters, including coherence length ζc(0), effective layer thickness d, penetration depth λpd(0), and Fermi energy E F showed improvement as the concentration of nano-(BSF) increased up to x = 0.04 wt.%. In addition to Ginzburg–Landau critical parameters, such as the thermodynamic critical field Bc(0), lower critical magnetic field Bc1(0), upper critical magnetic field Bc2(0), and critical current density Jc(0) demonstrated an increase up to x = 0.04 wt.%, followed by a decrease for higher concentrations. The magnetoresistance measurements were performed at various applied DC magnetic fields, with values ranging from 0.29 to 4.44 kG, and were analyzed using the thermally activated flux creep (TAFC) and Ambegaokar–Halperin (AH) models. The calculated flux pinning energy (U) increased with the addition of nano-(BSF) up to x = 0.04 wt.% and then decreased for x > 0.04 wt.%. Furthermore, the transition width (ΔT), was observed to increase as the applied magnetic field values increased. Moreover, the addition of nano-(BSF) increased the field-independent critical current density, Jc,0(0), up to x = 0.04 wt.%, after which it decreased for higher concentrations. [ABSTRACT FROM AUTHOR]

In this paper, we have extracted transport critical current density ( J c ) of BaZrO3 (BZO) added YBa2Cu3O 7 − δ (YBCO) by using several low electric field (E)-based criteria. By varying E-based criteria in order of magnitude, we have extracted J c (T) and granular critical current density, J c G (T) by using JE (IV) characteristics. The temperature (T) dependence of J c and J c G is found to be affected strongly as a result of the choice of E as criterion. The sensitiveness of J c and J c G becomes prominent with the lowering of T. The Ambegaokar–Baratoff (AB) and the Ginzburg–Landau (GL) descriptions of J c (T) and J c G (T) have been studied to understand how varying criteria may change the extraction of several associated coefficients. Extrapolated J c (T = 0) and J c G (T = 0) is also highly sensitive to criteria used. [ABSTRACT FROM AUTHOR]

In this work, a new kind of YGdBa4CuNbO y (YGdNb-11411) nano-particles was designed and sintered using a solid-state reaction method, whereas their impact on the performance of GdBCO bulks was investigated for the first time. From the acquired x-ray diffraction data and scanning electron microscopy imaging results, it was proved that the YGdNb-11411 particles were of excellent chemical stability and did not react with other phases during the crystal growth process. The YGdNb-11411 particles ranged from 80 to 130 nm and they were uniformly distributed in the well-textured GdBCO bulk superconductors. The maximum critical current density (J c-max) of the samples was enhanced from 3.48 × 104 A cm−2 to 8.63 × 104 A cm−2 (77 K) in the self-field as the doping amount increased from 0 wt% to 7 wt%. In addition, the GdBCO sample with YGdNb-11411 particles also showed an enhanced flux pinning force density and relatively high J c around the magnetic flux density range of 1 T–2 T (77 K). These results clearly indicated that the YGdNb-11411 particles could effectively enhance the properties of the GdBCO bulk superconductors. [ABSTRACT FROM AUTHOR]

Remanent magnetization of Y0.5Lu0.5Ba2Cu3Oy superconductor produced by a modified melt powder melt growth (MPMG) technique at 25 K temperature has been investigated by both experimental and numerical computations using H-formulation in the finite element method (FEM). At the low field and low-temperature conditions, remanent magnetization MREM is equal to the difference between the field cooled magnetization MFC and zero field cooled magnetization MZFC. Experimental data for remanent magnetization as a function of temperature can be reproduced quite well by numerical computations based on H-formulation providing an estimation of how the critical current density varies with temperature. The critical current density at 25 K was estimated to be a 6.50 × 108 A/m2, and the temperature dependence is determined as (1 − T/Tc)2.5 from the best fit curve of MREM(T) for the sample studied. In numerical calculations, we have used Jc(H) = Jc0/(1 + H/HREF), where HREF is a constant characterizing the superconducting sample. Furthermore, both flux density profile and current density profile have been obtained from the numerical calculations for various stages of the field applications or temperature values during the heating process. [ABSTRACT FROM AUTHOR]

Safety concerns caused by organic liquid electrolyte in lithium battery might limit its application. Li 7 La 3 Zr 2 O 12 is a promising electrolyte for solid-state lithium batteries due to its high ionic conductivity and interfacial stability with lithium. The influence of Ta doping on the structure, transport property and ionic conductivity of Li 7−x La 2.95 Yb 0.05 Zr 2−x Ta x O 12 (0 ≤ x ≤ 0.2) has been investigated. Ta drives some Li ions from 24d to 96 h site and simultaneously optimizes the size of Li ion transport pathway. This structure modification increases the mobility, jump rate, and diffusion coefficient of lithium ion. Besides, the densification and grain contact have also been enhanced. The ionic conductivity of Li 6.85 La 2.95 Yb 0.05 Zr 1.85 Ta 0.15 O 12 reaches 1.07 × 10−3 S cm−1 at 30 °C. The solid-state battery assembled with Li 6.85 La 2.95 Yb 0.05 Zr 1.85 Ta 0.15 O 12 exhibits high critical current density of 1.1 mA cm−2 and discharge capacity of 166.7 mAh g−1, indicating that Li 6.85 La 2.95 Yb 0.05 Zr 1.85 Ta 0.15 O 12 is a competitive solid electrolyte for solid-state lithium batteries. • High conductivity is achieved in Yb-Ta codoped LLZO by optimizing Li+ occupation. • Enhanced ionic conductivity and grain contact result in high critical current density. • Optimized size of ion diffusion pathway improves the transport behavior of Li ion. [ABSTRACT FROM AUTHOR]

The non-toxic copper oxide superconductor, (Cu,C)Ba2Ca3Cu4O11+δ or (Cu,C)-1234, exhibits the highest irreversibility magnetic field among superconducting materials in the liquid nitrogen temperature range and can achieve a superconducting transition temperature of 117 K, providing a new sample system for physical studies of copper oxide high-temperature superconductors. This article examines the underlying mechanisms that contribute to the high critical transition temperature, high critical current density, and notable irreversibility field properties observed in superconductors based on (Cu,C)-1234 copper. It also investigates the recent advancements made in the methods employed for the fabrication of bulks and thin films of this superconductor. Additionally, a comparison is made between the performance parameters of (Cu,C)-1234 superconductors and other superconducting materials that possess critical temperatures surpassing 100 K. This comparison highlights the distinctive characteristics and advantages of (Cu,C)-1234. Finally, we present potential future applications in the fields of energy transmission, magnetic levitation, and scientific research. [ABSTRACT FROM AUTHOR]

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Among the chalcogenide solid-state electrolytes (SSEs), Na 3 SbS 4 is of particular importance because of its high ionic conductivity and compatibility with moist air, which reduces processing costs and favors large-scale industrial deployment. However, the cation doping effects on the electrochemical properties of the Na 3 SbS 4 remain elusive. Here, a series of Na (3-2x) Sb (1-x) Mo x S (4-x) I x (x = 0.05, 0.1 0.15, 0.2) SSEs were fabricated via the ball milling and melt quenching strategy. The valence state of Mo is revealed to be 4+ not 6+. A high ionic conductivity of 0.54 mS cm−1 and an excellent critical current density of 1.5 mA cm−2 was obtained at room temperature. The cycling life of the symmetric cell is up to 112 h. The as-prepared SSEs also exhibit outstanding chemical stability. This work provides insightful understanding of the valence state of cations and impacts on the electrochemical performance of chalcogenide SSEs, which are vital for designing optimal SSEs. [ABSTRACT FROM AUTHOR]

All‐solid‐state sodium ion batteries (ASSIBs) attract growing attention as the next generation of batteries due to their high energy density, excellent safety, and the abundance of sodium resources. As a vital component of ASSIBs, chalcogenide Na‐ion solid‐state electrolytes (SSEs) have been widely studied due to their high ionic conductivity and outstanding ductility. However, due to the susceptibility to organic solvents and moisture, no chalcogenide Na‐ion SSEs membrane has been reported while only thick SSEs pellets have been investigated, which introduces abundant "dead" weight and lowers the energy density of ASSIBs. Herein, utilizing the excellent air stability of Na3SbS4, a thin (∼220 μm) Na3SbS4 membrane is prepared in air via a facile dry‐film method with polytetrafluoroethylene fibrillation, which exhibits a high ionic conductivity of 0.19 mS cm and an excellent critical current density of 0.6 mA/cm2. In summary, the chalcogenide Na‐ion SSEs membranes with high ionic conductivity and the simple preparation process could be readily adopted by pragmatic high‐performance ASSIBs. [ABSTRACT FROM AUTHOR]

In this paper, the advantages and disadvantages of using B powder and C encapsulated B powder as a precursor during the production process of MgB2 with the addition of pyrene (C16H10) were investigated. Two MgB2 bulk samples with the addition of 10 wt % C16H10 of 1 g MgB2 were produced by the in-situ method using B powder and C encapsulated B powder. The C encapsulated B powder as a precursor was prepared by adding 10% C16H10 as a C source. From XRD and SEM analysis, a greater increase in MgO phase and a greater decrease in a-lattice parameter were observed for the sample produced with B, compared to the sample produced with C encapsulated B. The curves of critical current density (Jc) at 5 K showed a similar character for both samples. The Jc values at 5 K in self field were respectively obtained as 1.52 × 105 A/cm2 and 1.90 × 105 A/cm2 for the samples produced by B and C encapsulated B. The decrement ratio of in-field Jc at 20 K was less affected by increasing magnetic field for the sample produced using C encapsulated B due to the relatively higher increase in the irreversibility field (Hirr) and the upper critical magnetic field (Hc2) values. The Jc values at 20 K and 3 T were respectively determined as 1.49 × 104 A/cm2 and 1.93 × 104 A/cm2 for the samples produced with B and C encapsulated B. [ABSTRACT FROM AUTHOR]

FeSe1−xTex superconductor has a relatively simple crystal structure and a high superconducting transition temperature in bulk form at ambient pressure, which gives it great application potential. In this study, Nb is selected to partially replace Fe in FeSe0.4Te0.6 and a series of Fe1−xNbxSe0.4Te0.6 single crystals with x = 0, 0.01, 0.03, 0.06, and 0.1 were synthesized using the self-flux. The crystal structure and superconductivity are characterized by XRD and magnetization measurements. The fish-tail peak effect was observed in samples with x = 0, 0.01, and 0.03. The critical current density of the three samples with x = 0, 0.01, and 0.03 is estimated by using the Bean model. According to the Dew-Hughes model, the effect of Nb doping on the magnetic flux pinning behavior of FeSe0.4Te0.6 is also investigated. [ABSTRACT FROM AUTHOR]

The Y3Ba5Cu8O18 (Y358) superconductors were produced using the Melt-Powder-Melt-Growth (MPMG) method. In the crystal growth process, Y2O3 powder was used as a substrate in both powder and tablet form. The first sample was produced without using any buffer layer, the second sample was produced with a powdered Y2O3 buffer layer, and the third sample was produced with a tablet-form Y2O3 buffer layer. The effect of the Y2O3 substrate on the structural and physical properties of the Y358 superconductor samples was investigated. Superconducting phases were observed in all samples of Y358 through XRD measurements, confirming their presence. Samples fabricated using the powder and tablet forms of the Y2O3 substrate had a better microstructure than the sample fabricated without a Y2O3 substrate. The highest critical current density (Jc) value was obtained at 77 K for the Y358 sample produced with a Y2O3 powder substrate, and the Jc value was calculated as 1.2 × 104 A cm–2 according to the Bean model. [ABSTRACT FROM AUTHOR]

FeSe1−xTex superconductor has a relatively simple crystal structure and a high superconducting transition temperature in bulk form at ambient pressure, which gives it great application potential. In this study, Nb is selected to partially replace Fe in FeSe0.4Te0.6 and a series of Fe1−xNbxSe0.4Te0.6 single crystals with x = 0, 0.01, 0.03, 0.06, and 0.1 were synthesized using the self-flux. The crystal structure and superconductivity are characterized by XRD and magnetization measurements. The fish-tail peak effect was observed in samples with x = 0, 0.01, and 0.03. The critical current density of the three samples with x = 0, 0.01, and 0.03 is estimated by using the Bean model. According to the Dew-Hughes model, the effect of Nb doping on the magnetic flux pinning behavior of FeSe0.4Te0.6 is also investigated. [ABSTRACT FROM AUTHOR]

Solid‐state sodium batteries have garnered considerable interest. However, their electrochemical performance is hampered by severe interfacial resistance between sodium metal and inorganic solid electrolytes, as well as Na dendrite growth within the electrolytes. To address these issues, a uniform and compact SnF2 film is first introduced onto the surface of the inorganic solid electrolyte Na3.2Zr1.9Ca0.1Si2PO12 (NCZSP) to improve contact through an effective and straightforward process. Through experiments and computations, the in situ conversion reaction between SnF2 and molten Na is adequately confirmed, resulting in a composite conductive layer containing NaxSn alloys and NaF at the interface. As a result, the interfacial resistance of Na/NCZSP is significantly decreased from 813 to 5 Ω cm2, and the critical current density is dramatically increased to 1.8 mA cm−2, as opposed to 0.2 mA cm−2 with bare NCZSP. The symmetric cell is able to cycle stably at 0.2 mA cm−2 for 1300 h at 30 °C and exhibits excellent current tolerance of 0.3 and 0.5 mA cm−2. Moreover, the Na3V2(PO4)3/SnF2‐NCZSP/Na full cell displays excellent rate performance and cycling stability. The SnF2‐induced interlayer proves significant in improving interfacial contact and restraining sodium dendrite propagation, thus promoting the development of solid‐state sodium batteries. [ABSTRACT FROM AUTHOR]

This study aims to investigate the sintering mechanisms of magnesium diborides using spark plasma sintering and optimize the sintering process conditions. Three different precursor materials were used: (i) commercial powder MgB2, (ii) mixtures of magnesium and nano boron powder (Mg + 2B), and (iii) mixtures of Mg and MgB4 powder for an ' in-situ ' reactive synthesis. The density of the obtained bulks exceeds 90% of the theoretical density of the material. The structure and microstructure of the samples were analyzed using x-ray diffraction and scanning electron microscope, which were correlated with their superconducting properties. The critical current density (J c), pinning force (f p), and electrical resistivity (ρ) of the samples were also investigated. The results show that the in-situ reactive synthesis of MgB2 using magnesium and nano boron powder was the most effective method for producing high-quality samples with improved superconducting properties. The findings could lead to the development of more efficient methods for producing high-performance of MgB2 bulks. [ABSTRACT FROM AUTHOR]

Measurements of temperature dependent magnetization associated with trapped magnetic flux in single crystals of CaKFe4As4, CaK(Fe0.983Mn0.017)4As4 and MgB2 using zero-field-cooled and field-cooled protocols are presented. The results allow for the determination of the values of superconducting transition temperature, lower critical field and self-field critical current density. These are compared with the literature data. Possible experimental concerns are briefly outlined. Our results, on these known superconductors at ambient pressure, are qualitatively similar to those recently measured on superhydrides at megabar pressures (Minkov et al 2023 Nat. Phys. https://doi.org/10.1038/s41567-023-02089-1) and, as such, hopefully serve as a baseline for the interpretation of high pressure, trapped flux measurements. [ABSTRACT FROM AUTHOR]

In this study, the superconducting properties of MgB 2 bulk samples fabricated at different conditions were investigated. Ex situ MgB 2 samples were further mixed with Mg and B at different amounts and sintered at different times and temperatures. Using Raman spectroscopy, the bearing of electron-phonon (e-ph) coupling (EPC) has been investigated. The dependence of temperature on magnetization, M(T), along with the dependence of magnetic field on magnetization, M(H), were evaluated to analyze the superconducting characteristics. Using the McMillan formular, which is modified by Allen–Dynes, and the frequency of phonon located in the mid peak centre ω 2 (E 2g), the contribution of EPC, whose value is closely proportional to the variation of critical temperature was reckoned. The lowest EPC value was determined by Raman spectrum analysis to be 1.094 for the MgB 2 sample added with 0.5 Mg and sintered at 1000 °C for 1 h. In addition, the sample showed the lowest critical temperature along with the highest critical current density. The small bundle field (B sb) as well as the large bundle field (B lb) were obtained using the collective pinning theory, demonstrating the expansion of the small also the large bundle regimes under suitable sample fabrication conditions. Based on the dependence of temperature on normalized critical current density (j) and normalized small bundle field (B sb), δT c pinning is the predominant flux pinning mechanism across totally MgB 2 bulk samples. The model of Dew–Hughes confirmed that the addition of Mg along with B creates surface pinning in the matrix by analyzing the pinning properties. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Electrochemistry is the property of Journal of Electrochemistry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The study of granularity in superconducting films by using AC susceptibility has a crucial role in the development of and improvement in the ReBCO-coated conductors, which are a constantly evolving reality in the modern power applications of superconductivity. Specifically, the study of the granularity is essential because the ReBCO superconducting wires and tapes are far from the regularity of a single crystal while they often present an inter- and intragranular contribution to the critical current density. On the other hand, the AC susceptibility is a key part of the characterization of a granular sample because this technique is very sensitive to the presence of granularity in the superconductors and, moreover, the study of its first harmonic allows for determining pivotal properties such as the pinning energy as well as the dissipation processes acting in the sample. The pinning energy values and the granularity of an YBCO thin film have been studied by means of AC susceptibility measurements as a function of the AC amplitude, temperature, and DC field. In particular, the first harmonic imaginary component of the AC susceptibility χ1″ related to the dissipation processes of the sample has been studied. First, starting from the Brandt approach, the critical current density Jc and the pinning energy U of the sample have been extracted at 77 K by using the χ1″ measurements as a function of the AC amplitude at different AC frequencies and DC fields. From these measurements, a first signal of granularity appears. In order to confirm it, the temperature dependence of the χ1″ at different DC fields has been studied and a contribution deriving from the inter- and intragranular part of the sample has emerged. By taking the temperature corresponding to the crossover between the two contributions at the different DC fields, the intergranular and intragranular response has been separated. Successively, the temperature has been fixed to 77 K, together with an AC frequency equal to 1597.9 Hz, and the χ1″ as a function of the DC field at different AC amplitudes has been analyzed showing a clear presence of granularity in all the curves. By drawing the contour plot of the χ1″ with the DC and AC values, it was possible to determine the best parameters to put at 77 K in order to exploit the material for applications.

Garnet‐type solid‐state electrolytes are among the most reassuring candidates for the development of solid‐state lithium metal batteries (SSLMB) because of their wide electrochemical stability window and chemical feasibility with lithium. However, issues such as poor physical contact with Li metal tend to limit their practical applications. These problems were addressed using β‐SiC as an additive to the Li anode, resulting in improved wettability over Li6.75La3Zr1.75Ta0.25O12 (LLZTO) and establishing an improved interfacial contact. At the Li–SiC|LLZTO interface, intimacy was induced by a lithiophilic Li4SiO4 phase, whereas robustness was attained through the hard SiC phase. The optimized Li–SiC|LLZTO|Li–SiC symmetric cell displayed a low interfacial impedance of 10 Ω cm2 and superior cycling stability at varying current densities up to 5800 h. Moreover, the modified interface could achieve a high critical current density of 4.6 mA cm−2 at room temperature and cycling stability of 1000 h at 3.5 mA cm−2. The use of mechanically superior materials such as SiC as additives for the preparation of a composite anode may serve as a new strategy for robust garnet‐based SSLMB. [ABSTRACT FROM AUTHOR]

The superconducting joints of superconducting in situ MgB2 wires have been of great interest since the first MgB2 wires were manufactured. The necessity of joining fully reacted wires in applications such as NMR brings complexity to the methodology of connecting already reacted wires sintered under optimised conditions via a mixture of Mg + 2B and subsequential second heat treatment to establish fully superconducting MgB2 joints. Some of the data in the literature resolved such a procedure by applying high cold pressure and sintering at a low temperature. A topical review publication did not address in depth the question of whether cold sintering is a potential solution, suggesting that hot pressing is the way forward. In this paper, we discuss the potential joint interfacial requirements, suggesting a thermo-mechanical procedure to successfully form a superconductive connection of two in situ reacted wires in the presence of Mg + 2B flux. The critical current at 25 K of the researched junction achieved 50% Ic for an individual in situ wire. [ABSTRACT FROM AUTHOR]

In this paper influence of the excess Ca and Cu cations on the critical temperature (Tc) and critical transport current density (Jc) of high-temperature superconducting ceramics of the compositions (HTSC) Bi1.6Pb0.4Sr2Ca2.1Cu3.1Oy, Bi1.6Pb0.4Sr2Ca2.25Cu3.25Oy and Bi1.6Pb0.4Sr2Ca3Cu4Oy synthesized by the glass-ceramic method has been studied. The synthesis of superconducting ceramics was carried out on the basis of the glass phase, obtained by ultra-fast quenching of the melt. Melting of the mixture of starting components was carried out without the use of a crucible under the influence of IR radiant heating. Analysis of the elemental composition of the samples of the initial precursors showed a significant deviation from stoichiometry in oxygen (increase), as well as a decrease in calcium content. The synthesis of HTSC ceramics was carried out at a temperature of 849–850 °C for 96 h with intermediate grinding every 24 h. Studies of the phase composition of ceramic samples by X-ray diffraction have shown that HTSC ceramics consist only of a superconducting high-temperature phase Bi-2223. Studies of current-carrying characteristics by the four-point probe method according to the criterion of 1 µV/cm2 have shown that high-temperature superconducting ceramics of the compositions Bi1.6Pb0.4Sr2Ca2.1Cu3.1Oy, Bi1.6Pb0.4Sr2Ca2.25Cu3.25Oy and Bi1.6Pb0.4Sr2Ca3Cu4Oy have an increased density of critical transport current of 9.12 A/cm2, 7.62 A/cm2 and 7.26 A/cm2, respectively. At the same time, it was found that with a decrease in the content of Ca and Cu cations in HTSC ceramics, an increase in the critical current density is observed. [ABSTRACT FROM AUTHOR]