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[IEEE 2018 IEEE International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD) - Tianjin, China (2018.4.15-2018.4.18)] 2018 IEEE International Conference on Applied Superconductivity and Electromagnetic Devices (ASEMD) - Experimental Study on the Twist Characteristics of Novel HTS Square Wire with Different Structures
摘要： This paper presents the characteristics of novel high temperature superconducting (HTS) twisted square wires with different structure. First, the HTS tapes of 4 mm width are cut into 1 mm width HTS narrow tapes. Then, different numbers of HTS narrow tapes and narrow tape of copper are stacked to prepare a HTS square wire with three structures of 1 + 5c, 2 + 4c and 4 + 2c. Finally, the HTS square wires of these three structures were twisted, and the critical current characteristics of HTS tapes were tested under different twist pitches. The test results show that the twist pitch of the three structures is about 100 mm. The experimental results show that the preparation of HTS square wire with twisted characteristic better, which has broad application prospects in superconducting power equipment.
关键词： twist pitch,critical current,Novel high temperature superconducting twisted square wires,superconducting filaments
更新于2025-09-23 15:23:52
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Multi-field dependence responses and their micro-structure analysis in YBa <sub/>2</sub> Cu <sub/>3</sub> O <sub/>7a??x</sub> -based second-generation coated conductors with different protective layers by Nd-laser irradiations
摘要： High-temperature superconductors (HTS) are materials that hold great promise for future particle-accelerator plants. YBa2Cu3O7-x-based (YBCO) second-generation coated conductor coils can produce the intense field needed for ion confinement. Such coils can act as a radiation resistance magnet when exposed to radiation, and therefore, it is essential to better understand irradiation responses and defect creation in YBCO superconductors. The influence of laser or ion irradiation on the electrical characteristics of HTS has been studied previously; however, most results remain ambiguous and inconsistent. Degradation of or incremental changes in the critical current of the HTS tap are currently only observed and explained via irradiation dose. The relation between irradiation defects and macro-multi-field responses has yet to be established for YBCO tapes, for magnet design and operation. In this study, YBCO (2 G HTS) taps with Ag, Cu–Ag, and Cu protective cap layers were selected as targets of Nd-laser irradiation, at varying power. Irradiation defects were formed in YBCO taps, and irradiation dose was monitored as a function of superconducting properties and mechanical behaviors. The critical current and its N-values eventually degrade under intense Nd-laser irradiation, and the mechanical behavior of YBCO tapes shows nonlinear features after irradiation. Scanning electron microscopy and x-ray energy-dispersive spectrometry were applied to investigate the micro-defect changes that occurred in the taps after each Nd-laser irradiation dose. Micro-structural observations showed that the protective layers were critical for radiation resistance in YBCO taps. Furthermore, the macro-stress dependence of the critical current field was measured before and after Nd-laser irradiation to establish the relationship with micro-defect morphology by Nd-laser irradiation.
关键词： micro-structure analysis,YBa2Cu3O7-x,critical current,High-temperature superconductors,Nd-laser irradiation
更新于2025-09-23 15:19:57
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Self-assembled nanorods in YBCO matrix a?? a computational study of their effects on critical current anisotropy
摘要： In order to understand how the doping with self-assembled nanorods of different sizes and concentrations as well as applied magnetic fields affect the critical current anisotropy in YBa2Cu3O7?x (YBCO) thin films close to YBCO c-axis, we present an extensive and systematic computational study done by molecular dynamics simulation. the simulations are also used to understand experimentally measured Jc(θ) curves for BaHfO3, BaZrO3 and BaSnO3 doped YBCO thin films with the help of nanorod parameters obtained from transmission electron microscopy measurements. our simulations reveal that the relation between applied and matching field plays a crucial role in the formation of Jc(θ)-peak around YBCO c-axis (c-peak) due to vortex-vortex interactions. We also find how different concentrations of different size nanorods effect the shape of the c-peak and explain how different features, such as double c-peak structures, arise. In addition to this, we have quantitatively explained that, even in an ideal superconductor, the overdoping of nanorods results in decrease of the critical current. our results can be widely used to understand and predict the critical current anisotropy of YBco thin films to improve and develop new pinscapes for various transport applications.
关键词： critical current anisotropy,molecular dynamics simulation,YBCO,flux pinning,self-assembled nanorods
更新于2025-09-23 15:19:57
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In-field dependences of the critical current density J in GdBa2Cu3O7-d coated conductors produced by Zr irradiation and post-annealing at low temperatures
摘要： We report the influence of 6 MeV Zr4+ irradiation and post-irradiation annealing (200 °C) in the in-field dependences of the critical current densities Jc of 1.3 μm thick GdBa2Cu3O7-d coated conductors grown by co-evaporation. Samples were irradiated with 6 MeV Zr4+ and fluences between 2.3 × 10^11 cm^-2 and 3 × 10^12 cm^-2. The correlation between the superconducting critical temperature Tc and in-field dependences of Jc has been analyzed. In addition, random disorder introduced by irradiation was reduced by thermal annealed at 200 °C. The analysis of our experimental findings indicates that the optimal irradiation (reducing random disorder by annealing) results in the suppression of the self-field Jc of ≈10% and in-field Jc enhancements nearly doubled at about 5 T. A clear correlation between Tc, disorder and self-field Jc is observed. Additional random disorder and nanoclusters suppress systematically Tc and increase the flux creep relaxation at intermediate temperatures (reducing the characteristic glassy μ value).
关键词： E. Ion irradiation,A. Coated conductors,D. Critical current densities
更新于2025-09-19 17:15:36
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IR laser line scanning treatments to improve levitation forces in MgTi0.06B2 bulk materials
摘要： Infrared (IR) laser-line scanning has been widely used to induce different surface microstructures in a broad range of materials. In this work, this laser configuration was applied on the surface of MgTi0.06B2 bulk samples in order to ascertain its effects on their superconducting properties, particularly on the magnetic levitation forces. The microstructural changes produced by this type of laser treatment were investigated by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). It was observed that the thermal treatment induced by the laser improves grain connectivity in a layer of material just below the irradiated surface, in agreement with the observed improvement in critical current density values, Jc, which were estimated from isothermal magnetic hysteresis loops. A significant increment of both vertical (Fz) and lateral (Fx) magnetic levitation forces was achieved. Numerical calculations were performed to understand the experimental behaviour and to clarify how an improvement of Jc near the surface can improve the magnetic levitation force of these materials. In addition, the same studies were carried out in similar bulk samples but with nano-sized silver particle additions of 3 and 6 wt %, in the outer ring of the bulk, observing also an improvement of the levitation forces, albeit less than in samples without Ag because of the better performance of the original samples after laser treatment. These results are relevant to those studying superconductor fabrication and material fabrication modelling, essential for the development of technological applications of superconductors, and are based on microstructure control via application of a recently developed laser-line scan method.
关键词： MgTi0.06B2,Critical current,Magnetic levitation force,IR laser-line scanning
更新于2025-09-12 10:27:22
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Changes in Critical Parameters of GdBa <sub/>2</sub> Cu <sub/>3</sub> O <sub/> 7? <i>x</i> </sub> HTS-2G Due to Swift-Ion Irradiation
摘要： The influence of the ion irradiation 132Xe27t (167 MeV), 86Kr17t (107 MeV), and 40Ar8t (48 MeV) on critical properties (Ic, Tc, ΔTc) of superconductor tapes of the 2-nd generation GdBa2Cu3O7(cid:1)x (SuperOx) are studied. It is shown that the critical current slightly increases and the width of the transition to the superconducting state reduces at low doses of Xe-irradiation. The obtained results enable the authors to estimate the radiation resistance of this HTS-2G tape to the used irradiation. As for the critical temperature, its decrease begins at considerably higher fluences than the decrease in the critical current, and ΔTc also changes. The decrease in the critical current can be explained by the irradiation-induced disorder of coherent boundaries between crystallites. At the instant of Tc to zero, it is possible to roughly estimate the track radii induced by the ions.
关键词： critical temperature,radiation defects,HTS-2G tape,critical current,radiation resistance
更新于2025-09-10 09:29:36
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Probing the effect of interface on vortex pinning efficiency of one-dimensional BaZrO <sub/>3</sub> and BaHfO <sub/>3</sub> artificial pinning centers in YBa <sub/>2</sub> Cu <sub/>3</sub> O <sub/>7-x</sub> thin films
摘要： C-axis-aligned one-dimensional arti?cial pinning centers (1D-APCs) provide strong correlated pinning of magnetic vortices and enhance critical current density Jc in superconducting YBa2Cu3O7-x (YBCO) ?lms and coated conductors. A fundamental question arises on what determines the pinning ef?ciency of different 1D-APCs. To shed light on this question, this work investigates the correlation between the 1D-APC/YBCO interface and the pinning ef?ciency of 1D-APCs of BaHfO3 (BHO) and BaZrO3 (BZO) of comparable diameters of 5–6 nm. Intriguingly, a highly coherent BHO 1D-APC/YBCO interface is revealed even at a high BHO doping level of 6 vol. %, in contrast to a semi-coherent BZO 1D-APC/YBCO interface with a large number of dislocations. This leads to a profound effect on the pinning ef?ciency of these 1D-APCs. Speci?cally, a record high pinning force density peak Fp,max (cid:2) 182.0 GN m(cid:3)3 at Hmax > 9.0 T and 65 K is obtained in the former, which is 2.5 times of the best reported in the latter. Moreover, a ratio of Hmax to accommodation ?eld H* determined from the 1D-APC areal concentration is found up to 3.5 in the former in contrast to 0.7 in the latter, demonstrating the critical impact of the APC/YBCO interface on the pinning ef?ciency of 1D-APCs.
关键词： YBCO,critical current density,BZO,artificial pinning centers,BHO,vortex pinning
更新于2025-09-10 09:29:36
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Improvement of Superconducting Properties by Optimized Post-Heat Treatment for Nb3Al Wires Fabricated by RHQ
摘要： With extremely high critical current density (Jc) and excellent strain tolerance, Nb3Al superconductor is considered as an alternative to Nb3Sn for application of high-filed magnets. However, complexity in the phase formation of Nb3Al hinders the Nb3Al superconducting wires to satisfy the requirement of engineering applications at present. Here, we have reported the improved performance of simple-structured 18-filamnet jelly-roll Nb3Al precursor long wires fabricated with rapid heating and quenching (RHQ) process. After processed with RHQ heat-treatment under various heating conditions, the Nb3Al wire were post-heat treated at a temperature between 700 oC to 1100 oC. The phase formation and the superconducting properties of the wires were investigated. It has been found that even if the RHQ process deviates from the optimum processing state, the superconducting properties of the wire can be improved by appropriately selecting post-heat treatment conditions.
关键词： critical current density,Nb3Al wires,rapid heating and quenching process,superconductivity
更新于2025-09-10 09:29:36
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Experimental evidence of a very thin superconducting layer in epitaxial indium nitride
摘要： Indium nitride is one of the very few semiconductors which is known to have a superconducting phase at temperatures of Tc > 1 K. Superconductivity occurs in a window of carrier densities of approximately 1018–1020 cm?3. This is a very low density when compared to other superconductors (i.e. metals, alloys, high Tc oxides) and thus raises interesting fundamental questions as well as technological possibilities. In this paper we address one key question about the dimensionality of the superconducting state of InN by using angle dependent critical field measurements. Our samples were grown by two different growth techniques (chemical vapour deposition and plasma-assisted molecular beam epitaxy) on c-oriented sapphire, with and without a GaN buffer layer. In both cases we find that for film thicknesses much larger than the coherence length d ? ξ, the angle dependence of the critical field (down to T < 280 mK) with respect to the c-axis continues to be clearly two-dimensional, demonstrating a characteristic cusp when the angle crosses 90° with respect to the c-axis. This indicates that the superconducting electrons are most likely confined to a layer much thinner than the thickness of the InN film. Further we find the magnitude of the gap to be 2Δ(0)/kBTc = 3.6, very close to the BCS prediction.
关键词： indium nitride,penetration depth,angle dependent critical field,coherence length,critical current,superconductivity
更新于2025-09-09 09:28:46
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Properties of percolation channels in planar memristive structures based on epitaxial films of a YBa <sub/>2</sub> Cu <sub/>3</sub> O <sub/> 7? <i>δ</i> </sub> high temperature superconductor
摘要： The transport properties of the percolation channels of memristive structures based on YBa2Cu3O7?δ epitaxial ?lms were studied. Molecular electronics and Andreev re?ection spectroscopy were utilised, and the in?uence of the superconductive transition of electrodes on resistive switching effects in these structures was examined. Based on the analysis of the conductivity mechanisms in the obtained heterostructures, it is assumed that percolation channels form through a chain of domains disordered by oxygen about 10 nm in diameter, with a maximum Tc of 60 K. Zero-bias anomalies of the dynamic resistance of the studied structures display temperature dependence of the critical current of typical superconductor—normal—superconductor weak links within the framework of Kulik–Omel’yanchuk theory in the dirty limit. A simulation was used to determine the physical parameters of the studied heterostructures.
关键词： resistive switching memory,heterostructures,?lms,critical current,high temperature superconductors,oxygen vacancies
更新于2025-09-09 09:28:46