Superconductivity最新文献

{"title":"Microwave surface resistance in MgB2: Effect of Te and cubic-BN addition on flux flow and pinning","authors":"Andrea Alimenti ,&nbsp;Enrico Silva ,&nbsp;Kostiantyn Torokhtii ,&nbsp;Pablo Vidal García ,&nbsp;Petre Badica ,&nbsp;Adrian Crisan ,&nbsp;Mihai Alexandru Grigoroscuta ,&nbsp;Nicola Pompeo","doi":"10.1016/j.supcon.2025.100170","DOIUrl":"10.1016/j.supcon.2025.100170","url":null,"abstract":"<div><div>MgB<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> is a perspective superconductor for many power applications. How this potential refers also to microwave or radiofrequency applications is still to be determined. Although its ultimate surface resistance in zero field is not competitive with conventional metallic superconductors, its strong pinning properties can favor RF applications in a dc magnetic field. Nonetheless, the RF response in the vortex state has been relatively less studied, as well as the effect of artificial pinning centers on the microwave surface resistance in the mixed state. In this paper we study the surface resistance of spark-plasma-sintered MgB<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>, with and without Te and cubic-BN (cBN) addition, in a dc magnetic field up to 1.2 T. We summarize previous results on pure MgB<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>, and we present new data on Te- and cBN- added MgB<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>. We use a two-tone dielectric-loaded resonator to measure the field-dependent surface resistance at 16.5 and 26.7 GHz in the temperature range from 10 K to <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span>. By exploiting the simultaneous measurements at two frequencies, we extract the flux-flow resistivity, the pinning constant <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>p</mi></mrow></msub></math></span> and the depinning frequency <span><math><msub><mrow><mi>f</mi></mrow><mrow><mi>p</mi></mrow></msub></math></span>. The two-band nature of MgB<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> affects the field dependence of the flux-flow resistivity. The microscopic superconducting state is not affected by the addition of artificial pinning centers, indicating that Te and cBN do not affect interband or intraband scattering. Pinning shows a measurable trend towards an increase in the Te- and cBN- added samples at higher temperatures and fields. We finally compare the results to those obtained in bulk Nb<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>Sn, also in view of possible in-field RF applications such as microwave cavity-based haloscopes.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"14 ","pages":"Article 100170"},"PeriodicalIF":5.6,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144135149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Finite element approach for calculating stress distribution in non-circular high-temperature superconducting coils","authors":"Zhihua Li ,&nbsp;Li Lu ,&nbsp;Zhuoyan Zhong ,&nbsp;Wei Wu","doi":"10.1016/j.supcon.2025.100168","DOIUrl":"10.1016/j.supcon.2025.100168","url":null,"abstract":"<div><div>Complex stress distribution arises in high-temperature superconducting (HTS) coil based on REBCO coated conductors, which is affected by the applied winding tension, thermal stress during cooling down, and electromagnetic forces when energizing the coil. The material and structure of bobbin and overband also play an important role.</div><div>In this study, a finite element (FE) method model was proposed for analyzing the stress of HTS coils with non-circular geometries, especially the stresses arise from winding tension and overband. Compared to traditional analytical methods, this approach is not only applicable to circular coils but also to coils of other shapes, such as racetrack and D-shape coils that could hardly be calculated analytically. Comparison between the traditional analytical model and the proposed FE method model was obtained, which validated the latter one according to the simulation results on the radial and hoop stresses of two circular coils. Next, the proposed approach was used to analyze the stress distribution of a racetrack coil and a D-shaped coil. Furthermore, a comprehensive analysis of the stress distributions in the epoxy impregnated racetrack coil and the D-shaped coil was conducted, considering winding stress, thermal stress, electromagnetic stress, and the influence of overband. Finally, we calculated the winding stress in the racetrack coil considering nonlinear compressive behaviors. The results show that the stress distributions are quite different from the case that not considering compressibility.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"14 ","pages":"Article 100168"},"PeriodicalIF":5.6,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143878837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Two-band superconductivity in intercalated rhombohedral ZrNCl","authors":"Zhenkai Xie ,&nbsp;Ziheng Sun ,&nbsp;Xinmin Wang ,&nbsp;Junying Shen ,&nbsp;Liyuan Zhang","doi":"10.1016/j.supcon.2025.100169","DOIUrl":"10.1016/j.supcon.2025.100169","url":null,"abstract":"<div><div>The multiband superconductor offers a unique venue for investigating the interplay between Cooper pairing and inter-band interactions. Here we report the emergence of two-band superconductivity in hybridized superlattice Na<span><math><msub><mrow></mrow><mrow><mi>0.1</mi></mrow></msub></math></span>(1,3-diaminopropane)<span><math><msub><mrow></mrow><mrow><mi>0.25</mi></mrow></msub></math></span> ZrNCl. The intercalation of organic molecules and Na ions into the interlayer modulates the electronic structure near the Fermi surface, and promotes the emergence of intrinsic superconductivity with onset transition temperature <span><math><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>=</mo><mn>15</mn></mrow></math></span> K. Systematical investigations of upper critical field <span><math><msub><mrow><mi>H</mi></mrow><mrow><mi>c2</mi></mrow></msub></math></span> reveals that temperature dependence of <span><math><msub><mrow><mi>H</mi></mrow><mrow><mi>c2</mi></mrow></msub></math></span> can be well-described by two-band theory, yielding the out-of-plane and in-plane <span><math><msub><mrow><mi>H</mi></mrow><mrow><mi>c2</mi></mrow></msub></math></span> values of 2.9 T and 11.5 T, respectively. Furthermore, analysis of the reversible magnetization data confirms the intrinsic two-band characteristics, which deviate significantly from the predictions of the single-band Ginzburg–Landau(GL)model. Meanwhile, the superconducting state exhibits a two-fold rotational symmetry under in-plane magnetic fields, contrasting with the three-fold symmetric ZrNCl lattice. Angle-dependent <span><math><msub><mrow><mi>H</mi></mrow><mrow><mi>c2</mi></mrow></msub></math></span> behavior aligns with the three-dimensional (3D) anisotropic GL model. These findings establish the intercalated rhombohedral ZrNCl as a compelling platform for exploring multiband superconductivity.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"14 ","pages":"Article 100169"},"PeriodicalIF":5.6,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143878838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Split pulsed magnet combining high peak central magnetic field and long rise time for pulsed field magnetization of high temperature superconductors","authors":"Juntong Hu ,&nbsp;Wenjiang Yang ,&nbsp;Difan Zhou ,&nbsp;Peng Zhao ,&nbsp;Mingliang Bai ,&nbsp;Juzhuang Yan ,&nbsp;Haoran Jiang ,&nbsp;Tianxin Lan","doi":"10.1016/j.supcon.2025.100166","DOIUrl":"10.1016/j.supcon.2025.100166","url":null,"abstract":"<div><div>Split pulsed magnets are widely employed in high temperature superconducting (HTS) motor armature winding as magnetizing coils to implement in-situ pulsed field magnetization (PFM) for HTS field pole magnets. We have designed and developed a compact and portable split pulsed magnet, that balances a peak central magnetic field of nearly 7 T and a rise time of 24 ms, making it particularly suitable for PFM of HTS materials at lower temperatures. Single and two-step PFM experiments of HTS GdBa ₂Cu₃O<span><math><msub><mrow></mrow><mrow><mn>7</mn><mo>−</mo><mi>δ</mi></mrow></msub></math></span> (GdBCO) bulk in different temperature ranges are conducted and the maximum trapped fields <span><math><msub><mrow><mi>B</mi></mrow><mrow><mi>t</mi></mrow></msub></math></span> are observed to be <span><math><mrow><mo>&gt;</mo><mn>3</mn></mrow></math></span> T in the 40–50 K temperature range and nearly 4 T at 30 K in a 30 mm diameter GdBCO bulk. The trapped field results validate the excellent PFM ability of this designed split pulsed magnet and indicate a high trapped field (close to 4 T) can also be obtained in a coreless double armature. Moreover, multi-physical field responses of the split pulsed magnet during discharge are analyzed by a 3D field-circuit coupling model, which manifests that the split pulsed magnet is in a stable and safe operating state even under the highest charge voltage. Finally, this study may provide a novel clue for the development of coreless HTS bulk motors and suggest that HTS coreless motors can maintain a high air gap magnetic field while avoiding losses and thrust or torque fluctuations caused by iron core saturation under high magnetic fields.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"14 ","pages":"Article 100166"},"PeriodicalIF":5.6,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143855245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Single-gap two-band superconductivity well above the Pauli limit in non-centrosymmetric TaIr2B2","authors":"J. Kačmarčík ,&nbsp;Z. Pribulová ,&nbsp;T. Shiroka ,&nbsp;F. Košuth ,&nbsp;P. Szabó ,&nbsp;M.J. Winiarski ,&nbsp;S. Królak ,&nbsp;J. Jaroszynski ,&nbsp;T. Shang ,&nbsp;R.J. Cava ,&nbsp;C. Marcenat ,&nbsp;T. Klein ,&nbsp;T. Klimczuk ,&nbsp;P. Samuely","doi":"10.1016/j.supcon.2025.100167","DOIUrl":"10.1016/j.supcon.2025.100167","url":null,"abstract":"<div><div>Non-centrosymmetric superconducting materials represent an exciting class of novel superconductors featuring a variety of unconventional properties, including mixed-parity pairing and very high upper critical fields. Here, we present a comprehensive study of TaIr<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>B<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> (with <span><math><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>=</mo><mn>5</mn><mo>.</mo><mn>1</mn></mrow></math></span>\u0000 <!--> <!-->K), using a set of complementary experimental methods, including bulk- and surface-sensitive techniques. We provide evidence that this system is a two-band, yet it behaves as a single-gap superconductor with a strong coupling. The upper critical field of TaIr<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>B<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> significantly exceeds the Pauli limit and exhibits a nearly linear temperature dependence down to the lowest temperatures. This behavior, rarely seen in superconductors, is discussed in terms of anti-symmetric spin–orbit interaction, two-band-, and strong-coupling effects, as well as disorder.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"14 ","pages":"Article 100167"},"PeriodicalIF":5.6,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143860392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hysteresis loss scaling of round REBCO cable towards 20 T","authors":"Arend Nijhuis ,&nbsp;Ruben Lubkemann ,&nbsp;Gulio Annaballi ,&nbsp;Huan Jin ,&nbsp;Zichuan Guo ,&nbsp;Jinggang Qin ,&nbsp;Chao Zhou","doi":"10.1016/j.supcon.2025.100165","DOIUrl":"10.1016/j.supcon.2025.100165","url":null,"abstract":"<div><div>High Temperature Superconductor (HTS) cables are considered for use in tokamaks such as DEMO (EU) and Chinese next generation fusion device (CN) or compact fusion machines. HTS cables offer the advantage of increased operating temperature and field strength of the magnet coils. In particular for Central Solenoid (CS) coils, the HTS high current cabled conductor windings are exposed to fast ramping AC magnetic fields inducing AC losses. The AC loss in HTS cables for fusion is mainly explored at low magnetic field amplitudes due to lack of testing facilities at higher fields. However, since the operating field in CS coils may be up to 20 T, it is essential to obtain quantitative knowledge on the AC losses for the entire applied field range with reasonable accuracy. This is important for thermohydraulic analysis of the operating temperature margin in coil designs. A method is used here to scale the hysteresis loss of a REBCO cable without transport current, measured up to only 1.4 T, to the entire field and temperature range up to 20 T and 50 K respectively. The field shielding and penetration effects of a multi-layer REBCO CORC®-like cable are quantified by measurements on stacked tape samples with a Vibrating Sample Magnetometer (VSM) up to fields significantly higher than the round cable’s full penetration field, found to be at 4.2 T. For higher fields, using measured critical current (<span><math><msub><mrow><mi>I</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span>) data up to 19 T and an <span><math><msub><mrow><mi>I</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span>(<em>B</em>,<em>T</em>) scaling law for field (<em>B</em>) and temperature (<em>T</em>) serve to cover the required range of data within the window of coil operation parameters. Basic well-known theory on AC loss, particularly on the relation between hysteresis loss and critical current density against magnetic field, serves as a validation for this work.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"14 ","pages":"Article 100165"},"PeriodicalIF":5.6,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143833790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multiphysics multilayer modelling and simulation of HTS REBCO magnets carrying direct currents under AC magnetic fields","authors":"Xuezhi Luo ,&nbsp;Jun Ma ,&nbsp;Huaqian Xiao ,&nbsp;Zhixuan Zhang ,&nbsp;Chao Yuan","doi":"10.1016/j.supcon.2025.100157","DOIUrl":"10.1016/j.supcon.2025.100157","url":null,"abstract":"<div><div>High temperature superconducting homopolar inductor machine (HTS-HIM) is concerned and studied for electric aircraft because of its high power density, high efficiency, and high power-to-weight ratio. In an HTS-HIM, the high temperature superconducting magnets carrying DC currents under alternating background magnetic fields work as excitation magnets. Under extreme electromagnetic conditions, the voltage, loss, and temperature of the HTS magnets will increase because of the dynamic resistance effect. To predict the behaviors of the HTS magnet, it is necessary to analyze its electromagnetic-thermal characteristics by using a multiphysics model. This paper establishes a 2D axisymmetric multilayer multiphysics HTS magnet model based on the <strong><em>H</em></strong>-formulation. By using this multilayer multiphysics model, the electromagnetic-thermal characteristics of each turn can be analyzed. Meanwhile, this model can not only analyze the total loss and loss components of each layer under various operating conditions but also predict the temperature and quench behaviors of each part. The result shows that the loss components of the REBCO layer have distinct temperature dependence. When considering the thermal field effect, the magnetization loss of the REBCO layer reduces by 75% and the transport loss of the REBCO layer increases by 45% under high direct currents and high AC magnetic fields. Meanwhile, the temperature of the external turn is higher than the internal turn, and the external turn is at risk of quench in the operating process when the direct currents and AC magnetic fields are high. The multilayer multiphysics model is a powerful tool for designing, analyzing, and optimizing the HTS magnets in HTS-HIMs, and this multiphysics modelling technique can be utilized in modelling and simulating HTS REBCO magnets in various applications.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"14 ","pages":"Article 100157"},"PeriodicalIF":5.6,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143696133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stress accommodation in nanoscale dolan bridges designed for superconducting qubits","authors":"S. Skinner-Ramos ,&nbsp;M.L. Freeman ,&nbsp;D. Pete ,&nbsp;R.M. Lewis ,&nbsp;M. Eichenfield ,&nbsp;C. Thomas Harris","doi":"10.1016/j.supcon.2025.100158","DOIUrl":"10.1016/j.supcon.2025.100158","url":null,"abstract":"<div><div>Josephson junctions are the principal circuit element in numerous superconducting quantum information devices and can be readily integrated into large-scale electronics. However, device integration at the wafer scale necessarily depends on having a reliable, high-fidelity, and high-yield fabrication method for creating Josephson junctions. When creating Al/AlO<span><math><msub><mrow></mrow><mrow><mi>x</mi></mrow></msub></math></span> based superconducting qubits, the standard Josephson junction fabrication method relies on a sub-micron suspended resist bridge, known as a Dolan bridge, which tends to be particularly fragile and can often times fracture during the resist development process, ultimately resulting in device failure. In this work, we demonstrate a unique Josephson junction lithography mask design that incorporates stress-relief channels. Our simulation results show that the addition of stress-relief channels reduces the lateral stress in the Dolan bridge by more than 70% for all the bridge geometries investigated. In practice, our novel mask design significantly increased the survivability of the bridge during device processing, resulting in 100% yield for over 100 Josephson junctions fabricated.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"14 ","pages":"Article 100158"},"PeriodicalIF":5.6,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143828769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An adaptive-extended modeling to accelerate electromagnetic study and data generation in superconducting magnet applications","authors":"Mingyang Wang ,&nbsp;Haolan Chen ,&nbsp;Tiantian Cai ,&nbsp;Fangliang Dong ,&nbsp;Junjie Jiang ,&nbsp;Jie Sheng ,&nbsp;Zhuyong Li","doi":"10.1016/j.supcon.2025.100156","DOIUrl":"10.1016/j.supcon.2025.100156","url":null,"abstract":"<div><div>Superconducting magnets possess unique electromagnetic properties, making them applicable in fields such as nuclear magnetic resonance, maglev, and fusion. These applications generally involve diverse environments featuring AC or DC conditions, where superconducting properties are influenced by various factors. Specifically, the most concerning properties in high temperature superconducting (HTS) magnets include critical current, AC loss, screening current effects, and so on. Finite element method is widely used in reliable numerical studies for these properties. Several popular models have been proposed and developed to get higher precision and less calculation time. However, constrained by computational resources, they still have challenges in supporting high-throughput analysis. In various studies on electromagnetic characteristics of magnets, a substantial amount of data is often required to facilitate the introduction of artificial intelligence (AI) methods or optimization approaches. This paper proposes an adaptive-extended J-model to compute superconducting properties, further enhancing the efficiency of electromagnetic study and also serving to generate dataset for AI methods. It reduces computation time to only 20%–30% of that of the existing fastest model while maintaining similar levels of accuracy. By using this method as a data-generative tool, the dataset of a series of HTS solenoids including 2000 turns is expeditiously obtained and employed to predict the screening current induced field. The predictive performance is reliable under the dataset calculation time of mere minutes. This study significantly shortens the time to realize big dataset demands, accelerating electromagnetic study of superconducting magnets in various scenarios.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"13 ","pages":"Article 100156"},"PeriodicalIF":5.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microstructural evolution mechanism of Ba0.6KαFe2As2 Cu/Ag composite sheathed superconducting tapes","authors":"Wenchao Li ,&nbsp;Chen Guo ,&nbsp;Meng Han ,&nbsp;Minghui Tang ,&nbsp;Chiheng Dong ,&nbsp;Chao Yao ,&nbsp;Dongliang Wang ,&nbsp;Yanwei Ma","doi":"10.1016/j.supcon.2025.100154","DOIUrl":"10.1016/j.supcon.2025.100154","url":null,"abstract":"<div><div>Low-cost Cu/Ag composite sheathed Ba<span><math><msub><mrow></mrow><mrow><mi>0.6</mi></mrow></msub></math></span>K<span><math><msub><mrow></mrow><mrow><mi>α</mi></mrow></msub></math></span>Fe₂As₂ superconducting tapes have been the focus of considerable research interest in terms of superconducting properties and performance improvement. The K-doping content has a great influence on the transport critical current density (<span><math><msub><mrow><mi>J</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span>) of Cu/Ag composite sheathed tapes. This study analyzes the evolution occurring within the micro-composition and the mechanism affecting the transport <span><math><msub><mrow><mi>J</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> in Ba<span><math><msub><mrow></mrow><mrow><mi>0.6</mi></mrow></msub></math></span>K<span><math><msub><mrow></mrow><mrow><mi>α</mi></mrow></msub></math></span>Fe₂As₂ (0.42 <span><math><mo>≤</mo></math></span>\u0000 <span><math><mi>α</mi></math></span>\u0000 <span><math><mo>≤</mo></math></span> 0.54) raw material, by modulating the ratio of K. It has been demonstrated that both extremes of K content, namely an insufficient or excessive amount, have an adverse effect on phase purity of the powders. Consequently, this has a direct impact on the transport <span><math><msub><mrow><mi>J</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> of tapes. Cu/Ag tapes fabricated using a precursor powder with an optimal K ratio <span><math><mrow><mi>α</mi><mo>∼</mo></mrow></math></span>0.464 exhibited the highest performance, with a <span><math><msub><mrow><mi>J</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> of 5.8 × 10⁴ A cm ⁻² at 10 T and 4.2 K. The optimized Cu/Ag composite tapes have been found to have superior advantages for high-field applications.</div></div>","PeriodicalId":101185,"journal":{"name":"Superconductivity","volume":"13 ","pages":"Article 100154"},"PeriodicalIF":5.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143562940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}