Articoli di riviste: "High critical temperature superconductor"

1

Zhang, Ling-Yun, Jia-Tih Lin, Bo-Zang Li e Fu-Cho Pu. "Thermal Properties of High Temperature Superconductors: Soliton Statistics Approach". Modern Physics Letters B 11, n. 04 (10 febbraio 1997): 149–54. http://dx.doi.org/10.1142/s0217984997000207.

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We develop a soliton statistics approach to discuss the lattice effect of high temperature superconductor in the Davydov model on the basis of the bisoliton idea. We prove that lattice displacement in the Davydov model satisfies ϕ4 field form. Critical temperature of high temperature superconductor is studied from statistics of lattice kink. We have shown that the lattice effect is pronounced for thermal properties of high temperature superconductors. Comparision between theoretical and experimental results are good agreement for LaSrCuO and YBaCuO superconductor materials.

2

Jin, C.-Q., S.-C. Li, J.-L. Zhu, F.-Y. Li, Z.-X. Liu e R.-C. Yu. "High Critical Current Density of a MgB2 Bulk Superconductor High-pressure Synthesized Directly from the Elements". Journal of Materials Research 17, n. 3 (marzo 2002): 525–27. http://dx.doi.org/10.1557/jmr.2002.0073.

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We report the property studies of a MgB2 superconductor with high critical current density. The MgB2 superconductor was readily fabricated through a direct high-pressure synthesis of the respective elements. The obtained high-density MgB2 undergoes a sharp superconducting transition at 39 K. The bulk critical current density (Jc) of the sample was calculated on the basis of Bean's critical state model, and rather high critical current densities over a wide temperature range were obtained in comparison with the ambient prepared samples. The results highlight that high-pressure sintering would be a promising way to produce and search for this kind of intermetallic boride and the related superconductors.

3

Bigansolli, Antonio Renato, Tessie Gouvêa da Cruz, Francisco Romário de Souza Machado e Durval Rodrigues Jr. "Characterization of Bi2212 Superconductor Bulk Samples by Digital Image Processing". Advanced Materials Research 975 (luglio 2014): 128–33. http://dx.doi.org/10.4028/www.scientific.net/amr.975.128.

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The use of superconductors of high critical temperatures in applied superconductivity leads to higher operation temperatures and economy of cryogenic fluids. High temperature superconductor materials exhibits limited transport properties due to grain boundary weak-links and anisotropy on the critical currents. The texturing development in these superconductors decreases in an efficient way the number of high-angle grain boundaries, increasing the values of critical current densities (Jc). In this research the size grain distribution characterization of Bi2212 superconductor bulk samples heat treated under the influence of an applied external magnetic field of 5T was carried out combining processing and images analysis obtained by SEM and statistical methodologies. The objective is to investigate influence of an external magnetic field applied during the heat treatment profiles on the texturing of Bi2Sr2CaCu2O8+δ (Bi2212) bulk by using complementary analytical techniques.

4

M.E., Emetere, Awojoyogbe O.B., Uno U.E., Isah K.U., Sanni E.S. e Akinyemi M.L. "How Reliable is the Cuprates System to Recent Technology?" International Journal of Electrical and Computer Engineering (IJECE) 6, n. 4 (1 agosto 2016): 1534. http://dx.doi.org/10.11591/ijece.v6i4.10082.

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The emergence of cuprates as a high Tc superconductor gave high hopes in the discovery of a room temperature superconductor. It is almost three decades and the highest critical temperature attained on the cuprates is about 135K. A brief overview was conducted on the progress made so far on the cuprates. A mathematical approach was used to design a formula which could determine the experimental results of critical temperature of versed cuprates superconductors. The result of our findings shows that the possibility of attaining the experimental room temperature cuprates superconductor seems very narrow. The study recommended an elaborate approach on the hybridization of cuprates for future research. Hence, there is possibility of having cuprates with wide engineering application.

5

M.E., Emetere, Awojoyogbe O.B., Uno U.E., Isah K.U., Sanni E.S. e Akinyemi M.L. "How Reliable is the Cuprates System to Recent Technology?" International Journal of Electrical and Computer Engineering (IJECE) 6, n. 4 (1 agosto 2016): 1534. http://dx.doi.org/10.11591/ijece.v6i4.pp1534-1540.

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The emergence of cuprates as a high Tc superconductor gave high hopes in the discovery of a room temperature superconductor. It is almost three decades and the highest critical temperature attained on the cuprates is about 135K. A brief overview was conducted on the progress made so far on the cuprates. A mathematical approach was used to design a formula which could determine the experimental results of critical temperature of versed cuprates superconductors. The result of our findings shows that the possibility of attaining the experimental room temperature cuprates superconductor seems very narrow. The study recommended an elaborate approach on the hybridization of cuprates for future research. Hence, there is possibility of having cuprates with wide engineering application.

6

Гуламова, Д. Д., А. В. Каримов, Д. Г. Чигвинадзе, С. М. Ашимов, О. В. Маградзе, С. Х. Бобокулов, Ж. Ш. Турдиев e Х. Н. Бахронов. "Исследование критической температуры T-=SUB=-c-=/SUB=- гомофазных сверхпроводников (Bi-=SUB=-1.7-=/SUB=-Pb-=SUB=-0.3-=/SUB=-Sr-=SUB=-2-=/SUB=-Ca-=SUB=-(n-1)-=/SUB=-Cu-=SUB=-n-=/SUB=- O-=SUB=-y-=/SUB=- (n=3, 4, 5) и вольт-амперных характеристик сэндвич-пар полупроводник InP-сверхпроводник Bi/Pb (2223, 2234, 2245)". Журнал технической физики 89, n. 4 (2019): 583. http://dx.doi.org/10.21883/jtf.2019.04.47317.2269.

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

7

Changjan, Arpapong, e Pongkaew Udomsamuthirun. "London Penetration Depth of Fe-Based Superconductors". Advanced Materials Research 979 (giugno 2014): 297–301. http://dx.doi.org/10.4028/www.scientific.net/amr.979.297.

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Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature. Fe-based superconductors are superconductors whose containing iron compounds and having a very high critical magnetic field. London penetration depth can assist in the study of the behavior of the critical magnetic field. The London penetration depth is the distance to which a magnetic field penetrates into a superconductor and becomes equal to 0.367879 times that of the magnetic field at the surface of the superconductor. In this paper, the London penetration depth of Fe-based superconductors is studied by Ginzburg-Landau scenery. Free energy of Fe-based superconductors is assumed by modified the free energy of two-band magnetic superconductors model and theof Fe-based superconductors is derived analytically. Finally, the temperature dependence of is investigated and applied to Single-Crystal superconductors.

8

Leroux, Maxime, Vivek Mishra, Jacob P. C. Ruff, Helmut Claus, Matthew P. Smylie, Christine Opagiste, Pierre Rodière et al. "Disorder raises the critical temperature of a cuprate superconductor". Proceedings of the National Academy of Sciences 116, n. 22 (13 maggio 2019): 10691–97. http://dx.doi.org/10.1073/pnas.1817134116.

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With the discovery of charge-density waves (CDWs) in most members of the cuprate high-temperature superconductors, the interplay between superconductivity and CDWs has become a key point in the debate on the origin of high-temperature superconductivity. Some experiments in cuprates point toward a CDW state competing with superconductivity, but others raise the possibility of a CDW-superconductivity intertwined order or more elusive pair-density waves (PDWs). Here, we have used proton irradiation to induce disorder in crystals of La1.875Ba0.125CuO4 and observed a striking 50% increase of Tc, accompanied by a suppression of the CDWs. This is in sharp contrast with the behavior expected of a d-wave superconductor, for which both magnetic and nonmagnetic defects should suppress Tc. Our results thus make an unambiguous case for the strong detrimental effect of the CDW on bulk superconductivity in La1.875Ba0.125CuO4. Using tunnel diode oscillator (TDO) measurements, we find indications for potential dynamic layer decoupling in a PDW phase. Our results establish irradiation-induced disorder as a particularly relevant tuning parameter for the many families of superconductors with coexisting density waves, which we demonstrate on superconductors such as the dichalcogenides and Lu5Ir4Si10.

9

MASTROPIETRO, V. "ANOMALOUS BCS EQUATION FOR A LUTTINGER SUPERCONDUCTOR". Modern Physics Letters B 13, n. 17 (20 luglio 1999): 585–97. http://dx.doi.org/10.1142/s0217984999000749.

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A self-consistence equation describing a superconductor whose normal state is a Luttinger liquid is computed in a rigorous way by renormalization group techniques. The gap and the critical temperatures are quite different with respect to the ones of normal superconductors (i.e. superconductors whose normal state is a Fermi liquid) and in particular, the critical temperature can be quite high for suitable values of the parameters. Such self-consistence equation can be obtained in a BCS mean field theory for a model of two Mattis models exchanging Cooper pairs. The connection of this model with recent theories of high T c superconductivity is briefly discussed.

10

Bigansolli, Antonio Renato, T. G. da Cruz e Durval Rodrigues Jr. "Nondestructive Analysis of Bi2212 Bulk Superconducting Ceramics in the C-Axis Direction". Materials Science Forum 869 (agosto 2016): 29–34. http://dx.doi.org/10.4028/www.scientific.net/msf.869.29.

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The use of superconductors of high critical temperatures in applied superconductivity leads to higher operation temperatures and economy of cryogenic fluids. High temperature superconductor materials exhibits limited transport properties due to grain boundary weak-links and anisotropy on the critical currents. The texturing development in these superconductors decreases in an efficient way the number of high-angle grain boundaries, increasing the values of the critical current densities. Several quantitative analysis methods have been developed to study the morphologic and topologic characteristics improving our understanding of structural parameters. In this work the grain size distribution characterization of Bi2Sr2CaCu2O8+δ Bi2212 superconductor bulk samples heat treated under the influence of an external applied magnetic field of 5T was carried out using a processing technique and analysis of images. The analyzed images were obtained by SEM in the c axis direction. All samples showed similar microstructures on both cases, but with the use of an external applied magnetic field during the heat treatments the average grain size decreased.

11

AHMAD, DAWOOD, TAE KWON SONG, IN SUK PARK, G. C. KIM, ZHI-AN REN e Y. C. KIM. "ANALYSIS OF MAGNETIC CRITICAL FIELDS IN IRON-BASED SmFeAsO0.85 HIGH-Tc SUPERCONDUCTOR". Modern Physics Letters B 25, n. 24 (20 settembre 2011): 1939–48. http://dx.doi.org/10.1142/s0217984911027200.

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The magnetic properties of the newly discovered iron-oxypnictide SmFeAsO 0.85 high-Tc superconductor with a Tc of around 55 K were investigated. Bulk SmFeAsO 0.85 was prepared by a method for high-pressure synthesis. The lower critical field H c1 was estimated from the magnetization at low fields; H c1 (0) was measured to be 212 Oe. A linear temperature dependence instead of saturation at low temperatures in H c1 (T) revealed unconventional superconductivity with a nodal gap structure in our SmFeAsO 0.85 superconductor. The results showed that the well-known secondary peak in the temperature dependence of the critical current density Jc is absent in the SmFeAsO 0.85 high-Tc superconductor. The irreversibility line B irr was fitted well by the power law dependence (1 - T/Tc)n with n ~ 1.5. This is indicative of the flux creep phenomena in the SmFeAsO 0.85 high-Tc superconductor. In addition, within the range of measurement temperatures in this study, no crossover was observed in the temperature dependence of the irreversibility line B irr which may be due to low anisotropy in our SmFeAsO 0.85 superconductor.

12

Chen, Honggang, Yongbo Li, Yao Qi, Mingzhong Wang, Hongyan Zou e Xiaopeng Zhao. "Critical Current Density and Meissner Effect of Smart Meta-Superconductor MgB2 and Bi(Pb)SrCaCuO". Materials 15, n. 3 (27 gennaio 2022): 972. http://dx.doi.org/10.3390/ma15030972.

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The smart meta-superconductor MgB2 and Bi(Pb)SrCaCuO increase the superconducting transition temperature (TC), but the changes in the transport critical current density (JC) and Meissner effect are still unknown. Here, we investigated the JC and Meissner effect of smart meta-superconductor MgB2 and Bi(Pb)SrCaCuO. The use of the standard four-probe method shows that Y2O3:Eu3+ and Y2O3:Eu3++Ag inhomogeneous phase significantly increase the JC, and JC decreases to a minimum value at a higher temperature. The Meissner effect was measured by direct current magnetization. The doping of Y2O3:Eu3+ and Y2O3:Eu3++Ag luminescent inhomogeneous phase causes a Meissner effect of MgB2 and Bi(Pb)SrCaCuO at a higher temperature, while the non-luminescent dopant reduces the temperature at which samples have Meissner effect. The introduction of luminescent inhomogeneous phase in conventional MgB2 and copper oxide high-temperature Bi(Pb)SrCaCuO superconductor increases the TC and JC, and Meissner effect is exerted at higher temperature. Therefore, smart meta-superconductivity is suitable for conventional and copper oxide high-temperature superconductors.

13

MOMENI, D., EIJI NAKANO, M. R. SETARE e WEN-YU WEN. "ANALYTICAL STUDY OF CRITICAL MAGNETIC FIELD IN A HOLOGRAPHIC SUPERCONDUCTOR". International Journal of Modern Physics A 28, n. 08 (21 marzo 2013): 1350024. http://dx.doi.org/10.1142/s0217751x13500243.

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We analytically study the effect of magnetic field in a holographic superconductor by using Sturm–Liouville method. We estimate the coefficient of proportionality at critical temperature and find its dependence on bulk magnetic field. By exploring the phase diagrams of critical temperature and magnetic field for various condensates, we conclude that the existence of critical magnetic field is a general feature in holographic superconductors. We also study the quantum phase transition at zero temperature and find that the critical charge density increases linearly with the condensate dimension.

14

POP, I., L. HOMORODEAN, I. BURDA e M. ANDRECUT. "STRUCTURAL, ELECTRICAL AND MAGNETIC PROPERTIES OF HIGH-TcYBa1.5Ca0.5Cu3O6+δ SUPERCONDUCTOR". Modern Physics Letters B 10, n. 27 (20 novembre 1996): 1349–53. http://dx.doi.org/10.1142/s0217984996001528.

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A high-Tc YBa 1.5 Ca 0.5 Cu 3 O 6+δ superconductor was synthesized, with the critical temperature Tc=84.9 K. The crystalline structure is orthorhombic with the lattice parameters a=3.8665 Å, b=3.9217 Å and c=11.7652 Å, characteristic for the 123 superconductors. The diamagnetic transition in the temperature dependence of the magnetic susceptibility strongly depends on the recycling of the samples and the onset of superconductibility is depressed by the magnetic field intensity.

15

Swinbanks, David. "High-critical-temperature superconductor made from glass". Nature 332, n. 6165 (aprile 1988): 575. http://dx.doi.org/10.1038/332575b0.

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Dahal, Kul Prasad. "Superconductivity: A Centenary Celebration". Himalayan Physics 2 (31 luglio 2011): 26–34. http://dx.doi.org/10.3126/hj.v2i2.5207.

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Superconductivity was empirically discovered 100 years ago. This paper describes briefly the history and developments in critical temperature of different superconductors. Many efforts have been put on research and development so as to raise critical temperature. Different superconducting materials both conventional and unconventional have been discovered. The phenomenon of superconductivity is widely applicable in different fields of S&T so as to ease human life and activities. High - temperature superconductors have taken central stage as a dream material after long research and development. Hitherto, superconductors have proven to be highly varied in composition but elusive and mysterious.Keywords: Centenary of superconductor; Chronological development of Tc; Conventional and unconventional superconductors; High temperature superconductors; Insufficiency of BCS theoryThe Himalayan Physics Vol.2, No.2, May, 2011Page: 26-34Uploaded Date: 1 August, 2011

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Chanpoom, Thaipanya. "The Isotope Effect Coefficient with Pseudogap and One-Band Superconductor". Key Engineering Materials 675-676 (gennaio 2016): 23–26. http://dx.doi.org/10.4028/www.scientific.net/kem.675-676.23.

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This research studied the isotope effect coefficient of high temperature superconductors. The model used one-band superconductor which considered the competition of superconducting gap and pseudogap in the below crossover temperature region. The isotope effect coefficient is derived and approximation in simplify form. We find that the isotope effect coefficient is decreased as the critical temperature Tc and the crossover temperature T* ratio Tc/T* increased.

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Zheng, Guo-qing. "High temperature spin-triplet topological superconductivity in K₂Cr₃As₃". Journal of Physics: Conference Series 2545, n. 1 (1 luglio 2023): 012001. http://dx.doi.org/10.1088/1742-6596/2545/1/012001.

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Abstract Spin-triplet superconductors are novel materials capable of harboring Majorana bound states that can be used in topological quantum computing. However, such bulk materials are still rare. Here we review the results that established K2Cr3As3 as a spin-triplet superconductor with transition temperature Tc as high as 6.5 K. We focus on the multiple-phases feature, and its exquisite distance to a ferromagnetic quantum critical point which is likely responsible for the high Tc . We touch on the topological aspects of the superconducting state, and suggest that it is a new route to the technical implementation using a topological spin-triplet superconductor at the highest temperature ever.

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Fang-Ying, Liang. "Critical Temperature Characteristics of Layered High-Temperature Superconductor Under Pressure". Communications in Theoretical Physics 51, n. 4 (aprile 2009): 761–64. http://dx.doi.org/10.1088/0253-6102/51/4/33.

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Li, Shaobo, Yabo Dan, Xiang Li, Tiantian Hu, Rongzhi Dong, Zhuo Cao e Jianjun Hu. "Critical Temperature Prediction of Superconductors Based on Atomic Vectors and Deep Learning". Symmetry 12, n. 2 (8 febbraio 2020): 262. http://dx.doi.org/10.3390/sym12020262.

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In this paper, a hybrid neural network (HNN) that combines a convolutional neural network (CNN) and long short-term memory neural network (LSTM) is proposed to extract the high-level characteristics of materials for critical temperature (Tc) prediction of superconductors. Firstly, by obtaining 73,452 inorganic compounds from the Materials Project (MP) database and building an atomic environment matrix, we obtained a vector representation (atomic vector) of 87 atoms by singular value decomposition (SVD) of the atomic environment matrix. Then, the obtained atom vector was used to implement the coded representation of the superconductors in the order of the atoms in the chemical formula of the superconductor. The experimental results of the HNN model trained with 12,413 superconductors were compared with three benchmark neural network algorithms and multiple machine learning algorithms using two commonly used material characterization methods. The experimental results show that the HNN method proposed in this paper can effectively extract the characteristic relationships between the atoms of superconductors, and it has high accuracy in predicting the Tc.

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Rientong, Komkrit, Nattawut Natkunlaphat e Udomsilp Pinsook. "Analysis of superconducting critical temperature using numerical method". Journal of Physics: Conference Series 2653, n. 1 (1 dicembre 2023): 012054. http://dx.doi.org/10.1088/1742-6596/2653/1/012054.

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Abstract Currently, many studies have shown that the critical temperature (Tc) of a superconductor can be predicted by using the BCS theory. In this work, we analyse Tc of superconductors, which is determined by the spectral function (α2F(ω)) derived from the interaction between electrons and phonons. The equation that we used for the calculation is T c strong = f 1 f 2 T c weak . In this equation, T c weak refers to the Allen-Dynes formula and f is the correction factor. We compare the Tc obtained from this equation with our method. Many important parameters are given and analysed, such as average coupling strength (λ), the square root of the average frequency square (ω2), and average logarithm frequency (ωln). We use numerical methods and expect to improve the equation to calculate Tc to be user-friendly. Normally, the calculation of Tc can be challenging and time-consuming. The most successful theory explaining the general properties of superconductors is the BCS theory. It explains the mechanism in which normal conductors become superconductors, and the pairing of electrons known as the Cooper pairing is formed by the electron-phonon interactions. In the past, the BCS theory predicted the limit of the critical temperature of superconductors to be around 30-40 kelvin. Recently, several researchers have been discovered a higher Tc value than the limited value from experiments under high pressure. Our method could provide a better analysis of appropriate Tc of superconductors to support new discoveries in the future.

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ŠTRBÍK, V., Š. BEŇAČKA, Š. GAŽI, Š. CHROMIK, J. LEVÁRSKY e J. SITH. "THE TEMPERATURE DEPENDENCE OF RESISTANCE AND CRITICAL CURRENT IN GRANULAR YBa2Cu3Ox SUPERCONDUCTING FILMS". Modern Physics Letters B 03, n. 09 (giugno 1989): 729–34. http://dx.doi.org/10.1142/s021798498900114x.

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Temperature dependence of resistance R(T) and critical transport current I c (T) was measured for high-Tc YBa 2 Cu 3 O x granular thin films prepared by vacuum co-evaporation. The results are interpreted in terms of superconductor-constriction-superconductor (ScS) or superconductor-normal metal-superconductor (SNS) models, shown to be more adequate than the superconductor-insulator-superconductor (SIS) one. The films with nearly the same superconducting phase transition can exhibit both metallic (dR/dT>0) or semiconductor (dR/dT<0) behavior at T>Tcon. This is ascribed to intragranular defects which are shunted below T con .

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Maksuwan, Atirat, Arpapong Changjan e Phanuchai Pramuanl. "THE APPLICATION OF ANALYSIS OF VARIANCE TO DIFFERENT IRON‑BASED SUPERCONDUCTOR CRITICAL TEMPERATURE MODELING". Suranaree Journal of Science and Technology 30, n. 4 (18 ottobre 2023): 030128(1–9). http://dx.doi.org/10.55766/sujst-2023-04-e02609.

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Recently, Iron-based superconductors have shown promising properties of high critical temperature and high upper critical fields, which are prerequisites for applications in highfield magnets. Extensive research has been conducted on a modeling approach that contributes to predicting doped Iron-based superconductor critical temperature from structural and topological parameters. Statistical significance of differences in modeling approaches requires studies that can reliably distinguish between systematic approach effects and errors resulting from modeling approach variation. In this work, we introduce analysis of variance (ANOVA) to assess the statistical significance of differences in modeling approach variation. Comparisons of obtained results with Iron-based modeling approach variation data of support vector machine (SVM) and linear regression with natural logarithm transformation (LRNLT) were presented.

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Idczak, Rafał, Wojciech Nowak, Bartosz Rusin, Rafał Topolnicki, Tomasz Ossowski, Michał Babij e Adam Pikul. "Enhanced Superconducting Critical Parameters in a New High-Entropy Alloy Nb0.34Ti0.33Zr0.14Ta0.11Hf0.08". Materials 16, n. 17 (24 agosto 2023): 5814. http://dx.doi.org/10.3390/ma16175814.

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The structural and physical properties of the new titanium- and niobium-rich type-A high-entropy alloy (HEA) superconductor Nb0.34Ti0.33Zr0.14Ta0.11Hf0.08 (in at.%) were studied by X-ray powder diffraction, energy dispersive X-ray spectroscopy, magnetization, electrical resistivity, and specific heat measurements. In addition, electronic structure calculations were performed using two complementary methods: the Korringa–Kohn–Rostoker Coherent Potential Approximation (KKR-CPA) and the Projector Augmented Wave (PAW) within Density Functional Theory (DFT). The results obtained indicate that the alloy exhibits type II superconductivity with a critical temperature close to 7.5 K, an intermediate electron–phonon coupling, and an upper critical field of 12.2(1) T. This finding indicates that Nb0.34Ti0.33Zr0.14Ta0.11Hf0.08 has one of the highest upper critical fields among all known HEA superconductors.

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Wiejaczka, J. A., e L. F. Goodrich. "Interlaboratory comparison on high-temperature superconductor critical-current measurements". Journal of Research of the National Institute of Standards and Technology 102, n. 1 (gennaio 1997): 29. http://dx.doi.org/10.6028/jres.102.004.

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Bracanovic, D., P. A. J. de Groot, M. Oussena, S. J. Porter, O. A. Mironov, S. J. Manton, Z. Yi, C. Beduz e P. C. McDonald. "The critical state in YBa2Cu3O7 − x high temperature superconductor". Cryogenics 37, n. 10 (gennaio 1997): 555–57. http://dx.doi.org/10.1016/s0011-2275(97)00044-1.

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Nakane, Hideaki, Yoshinobu Tarutani, Toshikazu Nishino, Hiroji Yamada e Ushio Kawabe. "DC-SQUID with High-Critical-Temperature Oxide-Superconductor Film". Japanese Journal of Applied Physics 26, Part 2, No. 11 (20 novembre 1987): L1925—L1926. http://dx.doi.org/10.1143/jjap.26.l1925.

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Charikova, Tatiana B., Nina G. Shelushinina, German I. Harus, Vladimir N. Neverov, Denis S. Petukhov, Olga E. Petukhova e Andrei A. Ivanov. "Anomalous Temperature Dependence of the Upper Critical Magnetic Field in Electron-Doped High-Temperature Superconductor". Solid State Phenomena 233-234 (luglio 2015): 729–32. http://dx.doi.org/10.4028/www.scientific.net/ssp.233-234.729.

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We present resistivity measurements of the upper critical field as a function of temperature for Nd2-xCexCuO4+δ/SrTiO3single crystal films near antiferromagnetic-superconducting phase boundary (x= 0.14) in magnetic fields up to 90kOe at temperatures down to 0.7K. The data are well described by a two-band/two-gap model for a superconductor in the dirty limit.

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Savchenko, M. A., e Elena Savchenko. "To the microscopic theory of the superconductive phase in antiferromagnetic metal compounds". Journal of V. N. Karazin Kharkiv National University, Series "Physics", n. 34 (16 luglio 2021): 15–18. http://dx.doi.org/10.26565/2222-5617-2021-34-02.

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The theory of the conductivity in antiferromagnetic metal compounds is constructed on the basic of the fluctuational theory of the magnetic superconductors. The superconductor in which there exist localized magnetic moments was considered. It is supposed that magnetic moments are orientated antiferromagnetically in basis plane of the crystal. An estimation for the critical temperature was obtained and necessary and enough conditions of the appearance of high-temperature superconductive phase in rare earth metal compounds were got. The criterion of an appearance of the high-temperature superconductive phase in antiferromagnetic compounds is found.

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Smolyaninov, Igor I., e Vera N. Smolyaninova. "Is There a Metamaterial Route to High Temperature Superconductivity?" Advances in Condensed Matter Physics 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/479635.

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Superconducting properties of a material such as electron-electron interactions and the critical temperature of superconducting transition can be expressed via the effective dielectric response functionεeff(q,ω) of the material. Such a description is valid on the spatial scales below the superconducting coherence length (the size of the Cooper pair), which equals ∼100 nm in a typical BCS superconductor. Searching for natural materials exhibiting larger electron-electron interactions constitutes a traditional approach to high temperature superconductivity research. Here we point out that recently developed field of electromagnetic metamaterials deals with somewhat related task of dielectric response engineering on sub-100 nm scale. We argue that the metamaterial approach to dielectric response engineering may considerably increase the critical temperature of a composite superconductor-dielectric metamaterial.

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Ishida, Shigeyuki, Daniel Kagerbauer, Sigrid Holleis, Kazuki Iida, Koji Munakata, Akiko Nakao, Akira Iyo et al. "Superconductivity-driven ferromagnetism and spin manipulation using vortices in the magnetic superconductor EuRbFe4As4". Proceedings of the National Academy of Sciences 118, n. 37 (7 settembre 2021): e2101101118. http://dx.doi.org/10.1073/pnas.2101101118.

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Magnetic superconductors are specific materials exhibiting two antagonistic phenomena, superconductivity and magnetism, whose mutual interaction induces various emergent phenomena, such as the reentrant superconducting transition associated with the suppression of superconductivity around the magnetic transition temperature (Tm), highlighting the impact of magnetism on superconductivity. In this study, we report the experimental observation of the ferromagnetic order induced by superconducting vortices in the high-critical-temperature (high-Tc) magnetic superconductor EuRbFe4As4. Although the ground state of the Eu2+ moments in EuRbFe4As4 is helimagnetism below Tm, neutron diffraction and magnetization experiments show a ferromagnetic hysteresis of the Eu2+ spin alignment. We demonstrate that the direction of the Eu2+ moments is dominated by the distribution of pinned vortices based on the critical state model. Moreover, we demonstrate the manipulation of spin texture by controlling the direction of superconducting vortices, which can help realize spin manipulation devices using magnetic superconductors.

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Khalid, Nurul Auni, Mohd Mustafa Awang Kechik, Nur Atikah Baharuddin, Chen Soo Kien, Hussein Baqiah, Lim Kean Pah, Abdul Halim Shaari et al. "Carbon nanofibers addition on transport and superconducting properties of bulk YBa2Cu3O7−δ material prepared via co-precipitation". Journal of Materials Science: Materials in Electronics 31, n. 19 (5 settembre 2020): 16983–90. http://dx.doi.org/10.1007/s10854-020-04255-0.

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Abstract The effects of carbon nanofibers addition on transport and superconducting properties of YBa2Cu3O7−δ (Y-123) superconductor were studied. Y-123 was prepared using co-precipitation method for good quality bulk of high temperature superconducting material. Carbon nanofibers with 0.2–0.8 wt% were added into Y-123 superconductors. The samples were characterized using electrical resistance measurement for critical temperature (Tc) and critical current density (Jc), powder X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray analysis. Most of the samples indicated a dominant Y-123 phase of an orthorhombic structure with a minor phase of BaCO3 and Y-124. Onset critical temperature was found to decrease from 90.5 to 80 K with increasing of carbon nanofibers concentration. The Jc for pure sample is 11 A/cm2 at 30 K while the Jc of sample with 0.4 wt% carbon nanofibers is 830 A/cm2 at 30 K. Introduction of carbon nanofibers enhanced Jc significantly. However, further addition of carbon nanofibers in Y-123 superconductor caused degradation in Jc.

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Tolendiuly, S., S. M. Fomenko, G. C. Dannangoda e K. S. Martirosyan. "Self-Propagating High Temperature Synthesis of MgB2 Superconductor in High-Pressure of Argon Condition". Eurasian Chemico-Technological Journal 19, n. 2 (30 giugno 2017): 177. http://dx.doi.org/10.18321/ectj649.

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Magnesium diboride can be synthesized under argon ambient, elevated or high pressures. High-pressure syntheses are promising methods for manufacturing of the bulk MgB2 superconductor material. We have been used high pressure of Ar gas in order to investigate its effect on properties of MgB2 superconductor such as critical temperature and current density. Bulk MgB2 superconductor was synthesized from elemental Mg–B powders in thermal explosion mode of self-propagating high-temperature synthesis (SHS) under argon pressure of 25 atm. XRD pattern of the as-synthesized product indicates an almost complete conversion of the reactants to the MgB2 single phase. Most of the diffractions peaks are related to the MgB2 polycrystalline bulk material. The impurity fraction is less than 24.3% in total sample and identified as MgO and MgB4 secondary phases. The positive effect of pressure of Ar gas during synthesis of MgB2 on critical current density JC has been confirmed. The critical current density of the sample was achieved in high pressure reactor was 3.8×106 A/cm2. A superconducting volume fraction of 16% under a magnetic field of 10 Oe was obtained at 5 K, indicating that the superconductivity was bulk in nature. The succeeded level of superconductor parameters of the high-pressure synthesized MgB2 and the possibility to produce a large bulk products make this technology very promising for practical applications.

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VERES, T., e M. CRISAN. "INFLUENCE OF THE ANTIFERROMAGNETIC CORRELATIONS ON THE CRITICAL TEMPERATURE OF THE HIGH TEMPERATURE SUPERCONDUCTORS". Modern Physics Letters B 05, n. 17 (20 luglio 1991): 1161–65. http://dx.doi.org/10.1142/s0217984991001416.

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The decreasing of the critical temperature of a high temperature superconductor due to the antiferromagnetic correlations and impurities has been calculated using a phenomenological model for the dynamic susceptibility considered in the explanations of the nuclear magnetic resonance, neutron scattering, tunneling experiments and the photoemission spectra. A good agreement with the experimental data has been obtained taking realistic values for the fit parameters.

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Méndez-Moreno, R. M. "A Schematic Two Overlapping-Band Model for Superconducting Sulfur Hydrides: The Isotope Mass Exponent". Advances in Condensed Matter Physics 2019 (10 ottobre 2019): 1–7. http://dx.doi.org/10.1155/2019/6795250.

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The high value of the isotope shift in sulfur hydrides supports a phonon-mediated pairing scenario of superconductivity for these high-temperature superconductors which are consistent with the Bardeen–Cooper–Schrieffer (BCS) framework. Knowing that a large electronic density of states enhances the critical temperature (Tc), generalized Fermi surface topologies are used to increase it. A multicomponent model within the BCS framework is proposed in this work for sulfur hydride superconductors. This model is used to evaluate some properties of the H3S superconductor. Strong and intermediate coupling effects are taken into account with the effective McMillan approximation, and the isotope coefficient is evaluated as a function of the coupling parameter as well as other relevant parameters of the model.

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Yang, Peidong, e Charles M. Lieber. "Nanostructured high-temperature superconductors: Creation of strong-pinning columnar defects in nanorod/superconductor composites". Journal of Materials Research 12, n. 11 (novembre 1997): 2981–96. http://dx.doi.org/10.1557/jmr.1997.0393.

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A chemical approach to the formation of columnar defects involving the growth and incorporation of MgO nanorods into high temperature superconductors (HTS's) has been developed. MgO nanorods were incorporated into Bi2Sr2CaCu2Oz, Bi2Sr2Ca2Cu3Oz, and Tl2Ba2Ca2Cu3Oz superconductors at areal densities up to 2 × 1010/cm2. Microstructural analyses of the composites demonstrate that the MgO nanorods create a columnar defect structure in the HTS matrices, form a compositionally sharp interface with the matrix, and self-organize into orientations perpendicular and parallel to the copper oxide planes. Measurements of the critical current density demonstrate significant enhancements in the MgO nanorod/HTS composites at elevated temperatures and magnetic fields compared with reference samples.

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Kong, Wei, Nurul Auni Khalid, Wani Nadhirah Titingan Nizam, Kim Yeow Tshai, Ing Kong, Eng Hwa Yap e Roslan Abd-Shukor. "Enhanced Transport Critical Current Density of Tl-1212 Bulk Superconductor Added with Nickel-Zinc Ferrite Nanoparticles". Solid State Phenomena 317 (maggio 2021): 125–30. http://dx.doi.org/10.4028/www.scientific.net/ssp.317.125.

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High temperature superconductor Tl-1212 with nominal starting composition (Tl0.85Cr0.15)Sr2CaCu2O7-δ was prepared with high purity oxide powders using a solid state reaction method. Small amounts of nickel-zinc ferrite nanoparticles (Ni0.5Zn0.5Fe2O4) at compositions 0.01, 0.02, 0.05 and 0.10 wt. % were added into Tl-1212 superconductors. The effect of Ni0.5Zn0.5Fe2O4 nanoparticles’ addition on the critical temperature (Tc), transport critical current density (Jc), phase formation, and morphology was studied. The samples were characterized using electrical resistance measurement, transport critical current density measurement, powder X-ray diffraction method (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Zero-resistance critical temperature (Tc-zero) was found to rise from 97 K to 99 K with increasing Ni0.5Zn0.5Fe2O4 nanoparticles concentration. The highest value recorded for transport critical current density (Jc) was 3,120 mA/cm2 at 77 K, which exhibited by sample with 0.02 wt. % of Ni0.5Zn0.5Fe2O4 nanoparticles. All samples showed a dominant Tl-1212 phase and exhibited tetragonal lattice structure in the P4/mmm space group. SEM micrographs showed close-packed microstructure with low porosity. EDX mapping showed that Ni0.5Zn0.5Fe2O4 nanoparticles were well distributed in the Tl-1212 samples. This study demonstrated that Ni0.5Zn0.5Fe2O4 nanoparticles have functioned as effective flux pinning centers to Tl-1212 superconductors and thus significantly enhanced its Jc.

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Lee, Sang Heon. "Measurement and Analysis of Magnetic Properties of YBa2Cu3O7-y Bulk Superconductor". Journal of Nanoelectronics and Optoelectronics 15, n. 1 (1 gennaio 2020): 122–26. http://dx.doi.org/10.1166/jno.2020.2671.

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YBa2Cu3O7-y single crystal bulk high-temperature superconductor has high critical current density with large magnetic levitation and trapping magnetic forces. Despite its distinctive electromagnetic properties, the longtime heat treatment process of oxide high-temperature superconductor, a ceramic material, is widely considered as a factor that can degrade industrial applicability of superconductors seriously. For applications in power systems, metal-ceramic composites need to be fabricated to enhance magnetic performance. In this study, CeO2 was utilized as an additive to control Y211 particles and improve superconducting magnetic properties. The study achieved meaningful outcomes, given that it reduced the processing time by half (1/2) with the interior seeding technique, realized the effect of top seeding by positioning one additional seed layer on the top surface, and obtained a magnetic levitation force of 67.015 N. In order to improve the physical properties of superconducting materials, interior seeding technique was applied, and the effect of top seeding was obtained by placing one seed layer on the top surface. Therefore, when two seed layers were used to fabricate a specimen, it could improve physical properties of superconductors to the extent that both the top and bottom pellets could be used.

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Bauch, T., D. Gustafsson, K. Cedergren, S. Nawaz, M. Mumtaz Virk, H. Pettersson, E. Olsson e F. Lombardi. "High critical temperature superconductor Josephson junctions for quantum circuit applications". Physica Scripta T137 (dicembre 2009): 014006. http://dx.doi.org/10.1088/0031-8949/2009/t137/014006.

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Lambrecht, S., e M. Ausloos. "Normal-state Nernst effect of a high-critical-temperature superconductor". Physical Review B 53, n. 21 (1 giugno 1996): 14047–50. http://dx.doi.org/10.1103/physrevb.53.14047.

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Wimbush, Stuart C., e Nicholas M. Strickland. "A Public Database of High-Temperature Superconductor Critical Current Data". IEEE Transactions on Applied Superconductivity 27, n. 4 (giugno 2017): 1–5. http://dx.doi.org/10.1109/tasc.2016.2628700.

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Goodrich, L. F., A. N. Srivastava e T. C. Stauffer. "Standard reference devices for high temperature superconductor critical current measurements". Cryogenics 33, n. 12 (dicembre 1993): 1142–48. http://dx.doi.org/10.1016/0011-2275(93)90008-c.

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Kong, Wei, Ing Kong, Mohd Mustafa Awang Kechik e Roslan Abd-Shukor. "Phase Formation and Electrical Transport Properties of Nano-Sized SnO₂ Added (Tl_0.85Cr_0.15)Sr₂CaCu₂O_7-δSuperconductors". Solid State Phenomena 268 (ottobre 2017): 315–19. http://dx.doi.org/10.4028/www.scientific.net/ssp.268.315.

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In this work, the effect of nano-sized SnO2 addition on the phase formation and electrical transport properties of (Tl0.85Cr0.15)Sr2CaCu2O7-δ (Tl-1212) superconductor was investigated. Thallium-based high temperature superconductor (HTS) with nominal starting composition (Tl0.85Cr0.15) Sr2CaCu2O7-δ was prepared using high purity oxide powders via solid state reaction method. Nano-sized SnO2 with 0.01 – 0.05 wt.% were added into Tl-1212 superconductors. The characteristic of the samples were determined by powder X-ray diffraction method (XRD), scanning electron microscopy (SEM), energy dispersive X-Ray analysis (EDX), electrical resistance measurements and transport critical current density measurements. Nano-sized SnO2 added (Tl0.85Cr0.15)Sr2CaCu2O7-δ showed Tc-zero between 93 and 95 K. All of the samples indicated a dominant phase of Tl-1212 with a minor phase of Tl-1201. The highest Jc (at 77 K) was shown by sample with 0.03 wt.% at 3260 mA/cm2. SnO2 has significantly enhanced the transport critical current density of Tl-1212 superconductor by acting as flux pinning centers. However, further addition of nano-sized SnO2 in Tl-1212 superconductor caused degradation in Jc. The SEM micrographs with energy dispersive X-Ray analysis (EDX) showed that SnO2 were well distributed in all the samples.

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Shi, Donglu. "Properties and Defects of Type II Superconductors". MRS Bulletin 16, n. 12 (dicembre 1991): 37–41. http://dx.doi.org/10.1557/s0883769400055330.

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Three major superconducting parameters can characterize a type II superconductor: critical transition temperature, Tc, upper critical magnetic field, Hc2, and critical current density, Jc. Because of the variety of crystal structures, chemical stoichiometrics, and microstructures of the materials, these superconducting parameters differ greatly from system to system.It has been found that the critical transition temperature is closely related to the crystal structure and stoichiometry. Previous studies have shown that compounds with a high degree of symmetry tend to be more favorable to superconductivity. Compounds with a cubic structure, such as a bcc structure, usually have higher Tc values than compounds with a hexagonal lattice. Among conventional superconductors, the so-called A-15 structure is most favorable for high transition temperatures. It is well known that many high Tc superconductors such as YBa2Cu3Ox and Bi2Sr2CaCu2Ox have an orthorhombic structure with a high degree of symmetry.The upper critical field, Hc2, is more complicated in terms of its relationship to structural characteristics. Experimental results have indicated that Hc2 is more closely related to the chemical stoichiometry and crystal structure than to the microstructure.However, the critical current density, Jc, can vary tremendously in a compound with a given crystal structure. The change in critical current density is associated with the so-called flux pinning that arises from the interaction between the flux lines and crystal defects. Thus, Jc is determined mostly by the microstructure of the materials.

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Larbalestier, David C., e Martin P. Maley. "Conductors from Superconductors: Conventional Low-Temperature and New High-Temperature Superconducting Conductors". MRS Bulletin 18, n. 8 (agosto 1993): 50–56. http://dx.doi.org/10.1557/s0883769400037775.

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A useful superconducting conductor must have several properties. Some of the key properties among these are illustrated by the cross section of a Nb-47wt%Ti/Cu composite (Figure 1) which was manufactured for the dipole magnets of the Superconducting Super Collider (SSC). It represents the state of the art for conventional conductor fabrication and is thus an excellent place to start in considering what is needed for any new conductor. First among the essential properties is a high critical current density (Jc); the lower limit of useful Jc is ~104 A/cm2, but really useful values lie between 105 and 106 A/cm2. The SSC conductor achieves this at fields up to 9 T at 4.2 K, the normal temperature used for magnets cooled by liquid helium.A critical second requirement is that the superconductor be paralleled by an intimately connected good normal conductor, in this case high-conductivity Cu. One function of the Cu is to stabilize the superconductor against small temperature disturbances that lead to flux jumps that could result in local quenching of superconductivity. This requirement forces the subdivision of a given cross section of the superconductor into many filaments having a maximum diameter of no more than about 50 μm, since bigger filaments store more electromagnetic energy than can safely be deposited in the filament without locally heating it above its critical temperature (Tc). One advantage of high-temperature superconducting (HTS) materials is that they can operate at temperatures above ~10 K. Since the specific heat is a strongly increasing function at low temperatures, this permits the safe filament size to greatly increase too. The need to minimize hysteresis losses, however, often provides a separate drive to minimize the filament diameter, as in the conductor of Figure 1, where there are some 7,000 filaments which are only 6 μm in diameter. The overall Cu:Nb-Ti ratio is about 1.5:1. This represents a compromise between the need to minimize the dilution of the supercurrent density by Cu and the need to provide sufficient high-conductivity normal metal to pass the current when the magnet makes the transition from the superconducting to the normal state (a quench).

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APOSTOL, MARIAN, FLORIN BUZATU e FANG HUA LIU. "CRITICAL TEMPERATURE OF THIRD GENERATION HIGH-TEMPERATURE SUPERCONDUCTORS". International Journal of Modern Physics B 04, n. 01 (gennaio 1990): 159–77. http://dx.doi.org/10.1142/s0217979290000103.

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The critical temperature of the Bi- and Tl-based superconductors is analyzed within the framework of the model of the interacting electrons and oxygen-displacive modes of the lattice. The presumable effect of the in-layer lattice modulation on the superconducting critical temperature is also estimated. The structural elements which seem to be effective in raising the critical temperature are discussed in comparison with the La- and Y-based superconductors.

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Herbirowo, Satrio, Hedy Putra Pratama, Akhmad Herman Yuwono, Nofrijon Sofyan e Agung Imaduddin. "A Comparative Study of the Manufacturing of BPSCCO Superconducting Wire with TiO₂ Dopants". Key Engineering Materials 897 (17 agosto 2021): 79–84. http://dx.doi.org/10.4028/www.scientific.net/kem.897.79.

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Bi-Pb-Sr-Ca-Cu-O (BPSCCO) superconductors are recognized as a projectable high-temperature superconductor for high-efficiency electrical applications. The addition of Ti enhances the formation of the Bi-2223 phase from the BPSCCO superconductor. The process of producing BPSCCO superconducting materials with TiO2 dopants is performed by the solid-state process and the production of wire rolling, consisting of bismuth (III) oxide powder (Bi2O3 = 99%), Strontium Carbonate powder (SrCO3 = 99%), Calcium Carbonate powder (CaCO3 = 99%), Copper Oxide powder (CuO2 = 99%), Lead Oxide powder (PbO2 = 98%) Bi: Pb: Sr: Ca: Cu ratio: 1.6: 0.4:2:2:3 doped by 1 %wt Titanium Oxide powder (TiO2 = 98.5%). The variables used in this study were the comparison of the sintering method at 860°C for 24 hours and 820 °C calcination for 20 hours, and 850°C sintering for 20 hours. The superconductor characterization was tested through the X-Ray Diffraction (XRD) test, Scanning Electron Microscopy (SEM), and Resistivity test. XRD test results showed the formation of Bi2Sr2CuO6 and Bi2Sr5Cu3O16 phase. SEM results showed an increase in grain size. The resistivity test results showed that all samples formed critical temperatures, 9.6 and 9.5K respectively.

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Maksimova A. N., Rudnev I. A., Kashurnikov I. A. e Moroz A. N. "Effect of an Array of Submicron Magnetic Dots on Magnetization, Critical Current, and the Structure of Vortex Configurations in HTS". Physics of the Solid State 65, n. 4 (2023): 517. http://dx.doi.org/10.21883/pss.2023.04.55989.500.

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A vortex lattice in a high-temperature superconductor (HTS) with an array of submicron magnetic dots on the surface has been studied by the Monte Carlo method within the framework of a three-dimensional model of a layered high-temperature superconductor. The adjustment of the vortex lattice to an array of magnetic points was observed --- ordered states arising in the process of remagnetization --- configurations of one, two, three, or more vortex filaments fixed to a single magnetic point. The occurrence of these configurations was accompanied by peaks on the magnetization curve. The influence of the HTS anisotropy on the adjustment of the vortex lattice is analyzed. The ordered configurations of the vortex lattice are also associated with the non-monotonic nature of the dependences of the superconductor critical current on the magnetic field. The influence of temperature, magnetic moment of points, and film thickness on the critical current is investigated. With an increase in temperature and a decrease in the magnetization of magnetic points, the maximum of the critical current shifts towards a lower field. The structure of vortex filaments in the inhomogeneous field of a magnetic point is analyzed in detail. The mechanism of the influence of ordered vortex configurations on magnetization and critical current is discussed. Keywords: high-temperature superconductor, magnetization curve, Abrikosov vortices, current-voltage characteristic, ferromagnetic pinning centers, Monte Carlo method.

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Lin, Dan, Han-Shu Xu, Jingjing Luo, Haoliang Huang, Yalin Lu e Kaibin Tang. "A Self-Doped Oxygen-Free High-Critical-Temperature (High-Tc) Superconductor: SmFFeAs". Inorganic Chemistry 58, n. 22 (novembre 2019): 15401–9. http://dx.doi.org/10.1021/acs.inorgchem.9b02464.

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Chew, A. D., A. Chambers e A. P. Troup. "Application of a high critical temperature superconductor bearing for high vacuum measurement". Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 15, n. 3 (maggio 1997): 759–62. http://dx.doi.org/10.1116/1.580816.

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