1
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Lavroff RH, Munarriz J, Dickerson CE, Munoz F, Alexandrova AN. Chemical bonding dictates drastic critical temperature difference in two seemingly identical superconductors. Proc Natl Acad Sci U S A 2024; 121:e2316101121. [PMID: 38547068 PMCID: PMC10998635 DOI: 10.1073/pnas.2316101121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 01/11/2024] [Indexed: 04/08/2024] Open
Abstract
Though YB6 and LaB6 share the same crystal structure, atomic valence electron configuration, and phonon modes, they exhibit drastically different phonon-mediated superconductivity. YB6 superconducts below 8.4 K, giving it the second-highest critical temperature of known borides, second only to MgB2. LaB6 does not superconduct until near-absolute zero temperatures (below 0.45 K), however. Though previous studies have quantified the canonical superconductivity descriptors of YB6's greater Fermi-level (Ef) density of states and higher electron-phonon coupling (EPC), the root of this difference has not been assessed with full detail of the electronic structure. Through chemical bonding, we determine low-lying, unoccupied 4f atomic orbitals in lanthanum to be the key difference between these superconductors. These orbitals, which are not accessible in YB6, hybridize with π B-B bonds and bring this π-system lower in energy than the σ B-B bonds otherwise at Ef. This inversion of bands is crucial: the optical phonon modes we show responsible for superconductivity cause the σ-orbitals of YB6 to change drastically in overlap, but couple weakly to the π-orbitals of LaB6. These phonons in YB6 even access a crossing of electronic states, indicating strong EPC. No such crossing in LaB6 is observed. Finally, a supercell (the M k-point) is shown to undergo Peierls-like effects in YB6, introducing additional EPC from both softened acoustic phonons and the same electron-coupled optical modes as in the unit cell. Overall, we find that LaB6 and YB6 have fundamentally different mechanisms of superconductivity, despite their otherwise near-identity.
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Affiliation(s)
- Robert H. Lavroff
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
| | - Julen Munarriz
- Departamento de Química Física and Instituto de Biocomputación y Física de Sistemas Complejos, Universidad de Zaragoza, Zaragoza50009, Spain
| | - Claire E. Dickerson
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
| | - Francisco Munoz
- Departamento de Física, Facultad de Ciencias, Universidad de Chile, Santiago7800024, Chile
- Center for the Development of Nanoscience and Nanotechnology, Santiago9330111, Chile
| | - Anastassia N. Alexandrova
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
- Department of Materials Science and Engineering, University of California, Los Angeles, CA90095
- California NanoSystems Institute, University of California, Los Angeles, CA90095
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2
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Putra RP, Oh JY, Jung SG, Park HS, Kang WN, Kang B. Enhancement in High-Field J c Properties and the Flux Pinning Mechanism of ZnO-Buffered MgB 2 Films. ACS OMEGA 2023; 8:11607-11613. [PMID: 37008078 PMCID: PMC10061634 DOI: 10.1021/acsomega.3c00809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 03/07/2023] [Indexed: 06/19/2023]
Abstract
We investigated the flux pinning properties in terms of the critical current density (J c) and pinning force density (F p) of MgB2 films with ZnO buffer layers of various thicknesses. At higher thicknesses of the buffer layer, significantly larger J c values are observed in the high-field region, whereas J c values in the low- and intermediate-field regions remain largely unaffected. A secondary point-pinning mechanism other than primary grain boundary pinning is observed in the F p analysis, which depends on the thickness of the ZnO buffer layer. Moreover, a close relationship between the Mg and B bond ordering and the fitting parameter of secondary pinning is obtained, indicating that the local structural distortion of MgB2 induced by ZnO buffer layers with different thicknesses may contribute to flux-pinning enhancement in the high-field region. Discovering further advantages of ZnO as a buffer layer other than the delamination resistance it provides will help to develop a MgB2 superconducting cable with a high J c for power applications.
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Affiliation(s)
- Rico Pratama Putra
- Department
of Physics, Chungbuk National University, Cheongju 28644, South Korea
| | - Jun Yung Oh
- Department
of Physics, Chungbuk National University, Cheongju 28644, South Korea
| | - Sun Gil Jung
- Department
of Physics, Sungkyunkwan University, Suwon 440 746, South Korea
| | - Han Seok Park
- Department
of Physics, Chungbuk National University, Cheongju 28644, South Korea
| | - Won Nam Kang
- Department
of Physics, Sungkyunkwan University, Suwon 440 746, South Korea
| | - Byeongwon Kang
- Department
of Physics, Chungbuk National University, Cheongju 28644, South Korea
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3
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Saltarelli L, Gupta K, Rasi S, Kethamkuzhi A, Queraltó A, Garcia D, Gutierrez J, Farjas J, Roura-Grabulosa P, Ricart S, Obradors X, Puig T. Chemical and Microstructural Nanoscale Homogeneity in Superconducting YBa 2Cu 3O 7-x Films Derived from Metal-Propionate Fluorine-free Solutions. ACS APPLIED MATERIALS & INTERFACES 2022; 14:48582-48597. [PMID: 36269760 PMCID: PMC9634695 DOI: 10.1021/acsami.2c11414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
Research involved in developing alternative energy sources has become a necessity to face global warming. In this context, superconductivity is an appealing solution to enhance clean electrical energy provided that lower production costs can be attained. By implementation of chemical solution deposition techniques and high-throughput growth methods, low-cost nanostructured epitaxial cuprate superconductors are timely candidates. Here, we present a versatile and tunable solution method suitable for the preparation of high-performance epitaxial cuprate superconducting films. Disregarding the renowned trifluoroacetate route, we center our focus on the transient liquid-assisted growth (TLAG) that meets the requirement of being a greener chemical process together with ultrafast growth rates beyond 100 nm/s. We developed a facile, fast, and cost-effective method, starting from the synthesis of metal-propionate powders of Y, Ba, and Cu of high purity and high yields, being the precursors of the fluorine-free solutions, which enable the chemical and microstructural nanoscale homogeneity of YBa2Cu3O7-x (YBCO) precursor films. These solutions present endured stability and enable precise tunability of the composition, concentration, porosity, and film thickness. Homogeneous precursor films up to thicknesses of 2.7 μm through eight layer multidepositions are demonstrated, thus establishing the correct basis for epitaxial growth using the fast kinetics of the TLAG process. YBCO films of 500 nm thickness with a critical current density of 2.6 MA/cm2 at 77 K were obtained, showing the correlation of precursor film homogeneity to the final YBCO physical properties.
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Affiliation(s)
- Lavinia Saltarelli
- Institut
de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
| | - Kapil Gupta
- Institut
de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
| | - Silvia Rasi
- Institut
de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
| | - Aiswarya Kethamkuzhi
- Institut
de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
| | - Albert Queraltó
- Institut
de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
| | - Diana Garcia
- Institut
de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
| | - Joffre Gutierrez
- Institut
de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
| | - Jordi Farjas
- GRMT,
Department of Physics, University of Girona, E17071 Girona, Catalonia, Spain
| | - Pere Roura-Grabulosa
- GRMT,
Department of Physics, University of Girona, E17071 Girona, Catalonia, Spain
| | - Susagna Ricart
- Institut
de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
| | - Xavier Obradors
- Institut
de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
| | - Teresa Puig
- Institut
de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
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4
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Abstract
Superconducting materials hold great potential to bring radical changes for electric power and high-field magnet technology, enabling high-efficiency electric power generation, high-capacity loss-less electric power transmission, small lightweight electrical equipment, high-speed maglev transportation, ultra-strong magnetic field generation for high-resolution magnetic resonance imaging (MRI) systems, nuclear magnetic resonance (NMR) systems, future advanced high energy particle accelerators, nuclear fusion reactors, and so on. The performance, economy, and operating parameters (temperatures and magnetic fields) of these applications strongly depend on the electromagnetic and mechanical properties, as well as the manufacturing and material cost of superconductors. This perspective examines the basic properties relevant to practical applications and key issues of wire fabrication for practical superconducting materials, and describes their challenges and current state in practical applications. Finally, future perspectives for their opportunities and development in the applications of superconducting power and magnetic technologies are considered.
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Affiliation(s)
- Chao Yao
- Key Laboratory of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing100049, China
| | - Yanwei Ma
- Key Laboratory of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing100049, China
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5
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Uniform Dispersion and Exfoliation of Multi-Walled Carbon Nanotubes in CNT-MgB 2 Superconductor Composites Using Surfactants. MATERIALS 2019; 12:ma12183044. [PMID: 31546855 PMCID: PMC6766284 DOI: 10.3390/ma12183044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Revised: 09/13/2019] [Accepted: 09/16/2019] [Indexed: 12/03/2022]
Abstract
We developed a novel yet commercially viable strategy of synthesizing superior high-TC superconducting composites by dispersing fully exfoliated carbon nanotubes (CNTs) uniformly throughout the grain of CNT-MgB2 composites. First, we optimized the amount of the surfactant required to produce a highly stable and homogeneous colloidal suspension of CNTs. This amount was found to be 1/8th of the amount of CNTs. Second, we prepared a homogeneous CNT-B mixture by adding amorphous nano-boron (B) to the colloidal CNT suspension. Next, two different MgB2 synthesis routes were explored. In one case, we mixed an appropriate amount of Mg in the CNT-B mixture and carried out sintering. In the second case, the CNT-B mixture was heat treated at 500 °C, prior to mixing with Mg and sintering to form CNT-MgB2. Both kinds of samples were rigorously characterized to obtain an insight into their properties. The direct synthesis route shows a clear exfoliation and uniform dispersion of CNTs with a critical current density (JC) of 104 A/cm2 at 3.5 T and 20 K, which is useful for the application in magnetic resonance imaging MRI magnet operating with a cryogen free cooler. Our JC(H) result is 10 times higher than that of the pure sample. By contrast, the performance of the sample subjected to heat processing before sintering was severely compromised given the formation of MgO. Despite its simplicity, the direct synthesis route can be used for the cost-effective fabrication of CNT–MgB2 superconducting composites.
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6
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Pushing the limits for the highest critical currents in superconductors. Proc Natl Acad Sci U S A 2019; 116:10201-10203. [PMID: 31085652 PMCID: PMC6534980 DOI: 10.1073/pnas.1905568116] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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8
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Bhagurkar AG, Yamamoto A, Wang L, Xia M, Dennis AR, Durrell JH, Aljohani TA, Babu NH, Cardwell DA. High Trapped Fields in C-doped MgB 2 Bulk Superconductors Fabricated by Infiltration and Growth Process. Sci Rep 2018; 8:13320. [PMID: 30190578 PMCID: PMC6127330 DOI: 10.1038/s41598-018-31416-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 08/14/2018] [Indexed: 11/17/2022] Open
Abstract
The grain boundaries in superconducting MgB2 are known to form effective magnetic flux pinning sites and, consequently, bulk MgB2 containing a fine-grain microstructure fabricated from nanoscale Mg and B precursor powders exhibits good magnetic field-trapping performance below 20 K. We report here that the trapped field of MgB2 bulk superconductors fabricated by an infiltration and growth process to yield a dense, pore-free microstructure, can be enhanced significantly by carbon-doping, which increases intra-band scattering within the superconducting grains. A maximum trapped field of 4.15 T has been measured at 7.5 K at the centre of a five-sample stack of Mg(B1−xiCxi)2 bulk superconductors processed by infiltration and growth, which not only represents a ~40% increase in trapped field observed compared to undoped bulk MgB2, but also is the highest trapped field reported to date in MgB2 samples processed under ambient pressure. The trapped field is observed to decay at a rate of <2%/day at 10 K, which suggests that bulk MgB2 superconductors fabricated using the infiltration and growth technique can be used potentially to generate stable, high magnetic fields for a variety of engineering applications.
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Affiliation(s)
- A G Bhagurkar
- Brunel Centre for Advanced Solidification Technology, Brunel University London, Uxbridge, UB8 3PH, UK.
| | - A Yamamoto
- Department of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo, 184-8588, Japan
| | - L Wang
- Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai, 200240, China
| | - M Xia
- Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai, 200240, China
| | - A R Dennis
- Department of Engineering, University of Cambridge, Trumpington Street, CB2 1PZ, Cambridge, UK
| | - J H Durrell
- Department of Engineering, University of Cambridge, Trumpington Street, CB2 1PZ, Cambridge, UK
| | - T A Aljohani
- National Centre for Advanced Materials, King Abdulaziz City for Science and Technology, Riyadh, 11442, Saudi Arabia
| | - N H Babu
- Brunel Centre for Advanced Solidification Technology, Brunel University London, Uxbridge, UB8 3PH, UK
| | - D A Cardwell
- Department of Engineering, University of Cambridge, Trumpington Street, CB2 1PZ, Cambridge, UK
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9
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Harran I, Chen Y, Wang H, Ni Y. Pressure induced evolution of structures and properties of iron tetraboride. CrystEngComm 2018. [DOI: 10.1039/c8ce00584b] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Iron tetraboride (FeB4) is attracting increasing attention due to its attractive electronic and mechanical properties (e.g., superconductivity and superhard).
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Affiliation(s)
- Ismail Harran
- School of Physical Science and Technology
- Key Laboratory of Advanced Technologies of Materials
- Ministry of Education of China
- Southwest Jiaotong University
- Chengdu 610031
| | - Yuanzheng Chen
- School of Physical Science and Technology
- Key Laboratory of Advanced Technologies of Materials
- Ministry of Education of China
- Southwest Jiaotong University
- Chengdu 610031
| | - Hongyan Wang
- School of Physical Science and Technology
- Key Laboratory of Advanced Technologies of Materials
- Ministry of Education of China
- Southwest Jiaotong University
- Chengdu 610031
| | - Yuxiang Ni
- School of Physical Science and Technology
- Key Laboratory of Advanced Technologies of Materials
- Ministry of Education of China
- Southwest Jiaotong University
- Chengdu 610031
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10
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Bhaumik A, Sachan R, Gupta S, Narayan J. Discovery of High-Temperature Superconductivity (T c = 55 K) in B-Doped Q-Carbon. ACS NANO 2017; 11:11915-11922. [PMID: 29116751 DOI: 10.1021/acsnano.7b06888] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We have achieved a superconducting transition temperature (Tc) of 55 K in 27 at% B-doped Q-carbon. This value represents a significant improvement over previously reported Tc of 36 K in B-doped Q-carbon and is the highest Tc for conventional BCS (Bardeen-Cooper-Schrieffer) superconductivity in bulk carbon-based materials. The B-doped Q-carbon exhibits type-II superconducting characteristics with Hc2(0) ∼ 10.4 T, consistent with the BCS formalism. The B-doped Q-carbon is formed by nanosecond laser melting of B/C multilayered films in a super undercooled state and subsequent quenching. It is determined that ∼67% of the total boron exists with carbon in a sp3 hybridized state, which is responsible for the substantially enhanced Tc. Through the study of the vibrational modes, we deduce that higher density of states near the Fermi level and moderate to strong electron-phonon coupling lead to a high Tc of 55 K. With these results, we establish that heavy B doping in Q-carbon is the pathway for achieving high-temperature superconductivity.
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Affiliation(s)
- Anagh Bhaumik
- Department of Materials Science and Engineering, North Carolina State University, Centennial Campus , Raleigh, North Carolina 27695-7907, United States
| | - Ritesh Sachan
- Department of Materials Science and Engineering, North Carolina State University, Centennial Campus , Raleigh, North Carolina 27695-7907, United States
- Materials Science Division, Army Research Office , Research Triangle Park, Durham, North Carolina 27709, United States
| | - Siddharth Gupta
- Department of Materials Science and Engineering, North Carolina State University, Centennial Campus , Raleigh, North Carolina 27695-7907, United States
| | - Jagdish Narayan
- Department of Materials Science and Engineering, North Carolina State University, Centennial Campus , Raleigh, North Carolina 27695-7907, United States
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11
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Getmanskii IV, Minyaev RM, Steglenko DV, Koval VV, Zaitsev SA, Minkin VI. From Two- to Three-Dimensional Structures of a Supertetrahedral Boran Using Density Functional Calculations. Angew Chem Int Ed Engl 2017; 56:10118-10122. [PMID: 28402596 PMCID: PMC5574009 DOI: 10.1002/anie.201701225] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 03/11/2017] [Indexed: 11/07/2022]
Abstract
With help of the DFT calculations and imposing of periodic boundary conditions the geometrical and electronic structures were investigated of two- and three-dimensional boron systems designed on the basis of graphane and diamond lattices in which carbons were replaced with boron tetrahedrons. The consequent studies of two- and three-layer systems resulted in the construction of a three-dimensional supertetrahedral borane crystal structure. The two-dimensional supertetrahedral borane structures with less than seven layers are dynamically unstable. At the same time the three-dimensional superborane systems were found to be dynamically stable. Lack of the forbidden electronic zone for the studied boron systems testifies that these structures can behave as good conductors. The low density of the supertetrahedral borane crystal structures (0.9 g cm-3 ) is close to that of water, which offers the perspective for their application as aerospace and cosmic materials.
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Affiliation(s)
- Iliya V. Getmanskii
- Institute of Physical and Organic ChemistrySouthern Federal University194/2 Stachka AvenueRostov-on-Don344090Russian Federation
| | - Ruslan M. Minyaev
- Institute of Physical and Organic ChemistrySouthern Federal University194/2 Stachka AvenueRostov-on-Don344090Russian Federation
| | - Dmitrii V. Steglenko
- Institute of Physical and Organic ChemistrySouthern Federal University194/2 Stachka AvenueRostov-on-Don344090Russian Federation
| | - Vitaliy V. Koval
- Institute of Physical and Organic ChemistrySouthern Federal University194/2 Stachka AvenueRostov-on-Don344090Russian Federation
| | - Stanislav A. Zaitsev
- Institute of Physical and Organic ChemistrySouthern Federal University194/2 Stachka AvenueRostov-on-Don344090Russian Federation
| | - Vladimir I. Minkin
- Institute of Physical and Organic ChemistrySouthern Federal University194/2 Stachka AvenueRostov-on-Don344090Russian Federation
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12
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Bhaumik A, Sachan R, Narayan J. High-Temperature Superconductivity in Boron-Doped Q-Carbon. ACS NANO 2017; 11:5351-5357. [PMID: 28448115 DOI: 10.1021/acsnano.7b01294] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report high-temperature superconductivity in B-doped amorphous quenched carbon (Q-carbon). This phase is formed after nanosecond laser melting of B-doped amorphous carbon films in a super-undercooled state and followed by rapid quenching. Magnetic susceptibility measurements show the characteristics of type-II Bardeen-Cooper-Schrieffer superconductivity with a superconducting transition temperature (Tc) of 36.0 ± 0.5 K for 17.0 ± 1.0 atom % boron concentration. This value is significantly higher than the best experimentally reported Tc of 11 K for crystalline B-doped diamond. We argue that the quenching from metallic carbon liquid leads to a stronger electron-phonon coupling due to close packing of carbon atoms with higher density of states at the Fermi level. With these results, we propose that the non-equilibrium undercooling-assisted synthesis method can be used to fabricate highly doped materials that provide greatly enhanced superconducting properties.
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Affiliation(s)
- Anagh Bhaumik
- Department of Materials Science and Engineering, Centennial Campus, North Carolina State University , Raleigh, North Carolina 27695-7907, United States
| | - Ritesh Sachan
- Department of Materials Science and Engineering, Centennial Campus, North Carolina State University , Raleigh, North Carolina 27695-7907, United States
- Materials Science Division, Army Research Office , Research Triangle Park, North Carolina 27709, United States
| | - Jagdish Narayan
- Department of Materials Science and Engineering, Centennial Campus, North Carolina State University , Raleigh, North Carolina 27695-7907, United States
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13
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(Li1−xFex)OHFeSe Superconductors: Crystal Growth, Structure, and Electromagnetic Properties. CRYSTALS 2017. [DOI: 10.3390/cryst7060167] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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14
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Getmanskii IV, Minyaev RM, Steglenko DV, Koval VV, Zaitsev SA, Minkin VI. From Two- to Three-Dimensional Structures of a Supertetrahedral Boran Using Density Functional Calculations. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201701225] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Iliya V. Getmanskii
- Institute of Physical and Organic Chemistry; Southern Federal University; 194/2 Stachka Avenue Rostov-on-Don 344090 Russian Federation
| | - Ruslan M. Minyaev
- Institute of Physical and Organic Chemistry; Southern Federal University; 194/2 Stachka Avenue Rostov-on-Don 344090 Russian Federation
| | - Dmitrii V. Steglenko
- Institute of Physical and Organic Chemistry; Southern Federal University; 194/2 Stachka Avenue Rostov-on-Don 344090 Russian Federation
| | - Vitaliy V. Koval
- Institute of Physical and Organic Chemistry; Southern Federal University; 194/2 Stachka Avenue Rostov-on-Don 344090 Russian Federation
| | - Stanislav A. Zaitsev
- Institute of Physical and Organic Chemistry; Southern Federal University; 194/2 Stachka Avenue Rostov-on-Don 344090 Russian Federation
| | - Vladimir I. Minkin
- Institute of Physical and Organic Chemistry; Southern Federal University; 194/2 Stachka Avenue Rostov-on-Don 344090 Russian Federation
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15
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Zaari H, Naji S, El Hachimi A, Benyoussef A, Kenz AA. The investigations of electronic structure, optical and magnetic properties of MgB<inf>2</inf> nanosheets. 2014 INTERNATIONAL RENEWABLE AND SUSTAINABLE ENERGY CONFERENCE (IRSEC) 2014. [DOI: 10.1109/irsec.2014.7059868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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16
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Cheng XY, Chen XQ, Li DZ, Li YY. Computational materials discovery: the case of the W–B system. ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY 2014; 70:85-103. [DOI: 10.1107/s2053229613027551] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 10/01/2013] [Indexed: 11/11/2022]
Abstract
By means of variable-compositional evolutionary algorithms, in combination with first-principles calculations, the compositions, structures and mechanical properties of the W–B system have been theoretically investigated. As well as confirming the experimental observations (including their crystal structures) for the four known compounds W2B, WB, WB2and WB3, the new stable compound W8B7and two nearly stable compounds, W2B3and WB4, have also been predicted in the ground state. The elastic properties and estimated Vickers hardnesses of all these borides have been systematically derived. The results show that, among these borides,hP6-WB2exhibits the largest ultra-incompressibility along thecaxis, with the highestC33value (953 GPa, comparable with that of the most incompressible diamond).hP16-WB3exhibits the highest hardness of 36.9 GPa, in good agreement with the experimentally measured data from 28.1 to 43.3 GPa, close to the superhard threshold, andoC8-WB shows the highest bulk modulus of about 350 GPa. The new stable compound W8B7crystallizes in the monoclinicmP15 phase, with infinite zigzag B chains running parallel to the W-atom layers, resulting in a relatively high estimated hardness of 19.6 GPa. The anisotropic Young's modulusEand torsion shear modulusGthave been derived for bothoC8-WB andhP16-WB3. The current state of research and the historic inconsistency of the W–B system are briefly summarized, in particular clarifying the fact that the previous experimentally attributedhP20-WB4is in fact the defect-containinghP16-WB3.
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17
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Plapcianu C, Agostino A, Badica P, Aldica GV, Bonometti E, Ieluzzi G, Popa S, Truccato M, Cagliero S, Sakka Y, Vasylkiv O, Vidu R. Microwave Synthesis of Fullerene-Doped MgB2. Ind Eng Chem Res 2012. [DOI: 10.1021/ie3005429] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- C. Plapcianu
- CNISM and NIS Center of Excellence, Department of Physics, University of Torino, Via P. Giuria 1, I-10125 Torino,
Italy
- NIS Center of Excellence,
Department of Chemistry, University of Torino, Via P. Giuria 7, I-10125 Torino, Italy
- National Institute of Materials Physics, 105 bis Atomistilor strasse, P.O. Box MG-7, 077125 Magurele, Ilfov,
Romania
| | - A. Agostino
- NIS Center of Excellence,
Department of Chemistry, University of Torino, Via P. Giuria 7, I-10125 Torino, Italy
| | - P. Badica
- National Institute of Materials Physics, 105 bis Atomistilor strasse, P.O. Box MG-7, 077125 Magurele, Ilfov,
Romania
| | - G. V. Aldica
- CNISM and NIS Center of Excellence, Department of Physics, University of Torino, Via P. Giuria 1, I-10125 Torino,
Italy
- National Institute of Materials Physics, 105 bis Atomistilor strasse, P.O. Box MG-7, 077125 Magurele, Ilfov,
Romania
| | - E. Bonometti
- NIS Center of Excellence,
Department of Chemistry, University of Torino, Via P. Giuria 7, I-10125 Torino, Italy
| | - G. Ieluzzi
- NIS Center of Excellence,
Department of Chemistry, University of Torino, Via P. Giuria 7, I-10125 Torino, Italy
| | - S. Popa
- National Institute of Materials Physics, 105 bis Atomistilor strasse, P.O. Box MG-7, 077125 Magurele, Ilfov,
Romania
| | - M. Truccato
- CNISM and NIS Center of Excellence, Department of Physics, University of Torino, Via P. Giuria 1, I-10125 Torino,
Italy
| | - S. Cagliero
- CNISM and NIS Center of Excellence, Department of Physics, University of Torino, Via P. Giuria 1, I-10125 Torino,
Italy
- NIS Center of Excellence,
Department of Chemistry, University of Torino, Via P. Giuria 7, I-10125 Torino, Italy
| | - Y. Sakka
- National Institute for Materials Science, 1-2-1 Sengen, Tsukuba
305-0051, Japan
| | - O. Vasylkiv
- National Institute for Materials Science, 1-2-1 Sengen, Tsukuba
305-0051, Japan
| | - R. Vidu
- University of California, 3123 Bainer Hall, Davis,
California
95616, United States
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18
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Park DK, Hahn S, Bascuñán J, Iwasa Y. Active Protection of an MgB(2) Test Coil. IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY : A PUBLICATION OF THE IEEE SUPERCONDUCTIVITY COMMITTEE 2011; 21:2402-2405. [PMID: 22081754 PMCID: PMC3212042 DOI: 10.1109/tasc.2010.2095812] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
This paper presents results of a study, experimental and computational, of a detect-and-activate-the-heater protection technique applied to a magnesium diboride (MgB(2)) test coil operated in semi-persistent mode. The test coil with a winding ID of 25 cm and wound with ~500-m long reacted MgB(2) wire was operated at 4.2 K immersed in a bath of liquid helium. In this active technique, upon the initiation of a "hot spot" of a length ~10 cm, induced by a "quench heater," a "protection heater" (PH) of ~600-cm long planted within the test coil is activated. The normal zone created by the PH is large enough to absorb the test coil's entire initial stored energy and still keeps the peak temperature within the winding below ~260 K.
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Affiliation(s)
- Dong Keun Park
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - Seungyong Hahn
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - Juan Bascuñán
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - Yukikazu Iwasa
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
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19
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Wang Y, Zhuang C, Gao J, Shan X, Zhang J, Liao Z, Xu H, Yu D, Feng Q. MgB2 Superconducting Whiskers Synthesized by Using the Hybrid Physical−Chemical Vapor Deposition. J Am Chem Soc 2009; 131:2436-7. [DOI: 10.1021/ja8087828] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yazhou Wang
- State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, P. R. China
| | - Chenggang Zhuang
- State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, P. R. China
| | - Jingyun Gao
- State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, P. R. China
| | - Xudong Shan
- State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, P. R. China
| | - Jingmin Zhang
- State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, P. R. China
| | - Zhimin Liao
- State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, P. R. China
| | - Hongjun Xu
- State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, P. R. China
| | - Dapeng Yu
- State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, P. R. China
| | - Qingrong Feng
- State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, P. R. China
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20
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Yu Z, Ma Y, Wang D, Gao Z, Zhang X. Fabrication of the 19-filament Fe/Cu clad MgB2 wire via in situ powder-in-tube method. CHINESE SCIENCE BULLETIN-CHINESE 2007. [DOI: 10.1007/s11434-007-0383-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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21
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Nath M, Parkinson BA. Superconducting MgB2 Nanohelices Grown on Various Substrates. J Am Chem Soc 2007; 129:11302-3. [PMID: 17715920 DOI: 10.1021/ja072475x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Manashi Nath
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
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22
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Zlotnikov I, Gotman I, Gutmanas E. Processing of dense bulk MgB2 superconductor via pressure-assisted thermal explosion mode of SHS. Ann Ital Chir 2005. [DOI: 10.1016/j.jeurceramsoc.2004.09.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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23
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Supercondcuting properties in MgB2/Fe wires prepared by PIT method. CHINESE SCIENCE BULLETIN-CHINESE 2003. [DOI: 10.1007/bf03184173] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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24
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Eisterer M, Zehetmayer M, Weber HW. Current percolation and anisotropy in polycrystalline MgB(2). PHYSICAL REVIEW LETTERS 2003; 90:247002. [PMID: 12857216 DOI: 10.1103/physrevlett.90.247002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2002] [Indexed: 05/24/2023]
Abstract
The influence of anisotropy on the transport current in MgB(2) polycrystalline bulk samples and wires is discussed. A model for the critical current density is proposed, which is based on anisotropic London theory, grain boundary pinning, and percolation theory. The calculated currents agree convincingly with experimental data, and the fit parameters, especially the anisotropy, obtained from percolation theory agree with experiment or theoretical predictions.
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Affiliation(s)
- M Eisterer
- Atominstitut der Osterreichischen Universitäten, A-1020 Vienna, Austria.
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25
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Larbalestier D, Gurevich A, Feldmann DM, Polyanskii A. High-Tc superconducting materials for electric power applications. Nature 2001; 414:368-77. [PMID: 11713544 DOI: 10.1038/35104654] [Citation(s) in RCA: 1027] [Impact Index Per Article: 44.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Large-scale superconducting electric devices for power industry depend critically on wires with high critical current densities at temperatures where cryogenic losses are tolerable. This restricts choice to two high-temperature cuprate superconductors, (Bi,Pb)2Sr2Ca2Cu3Ox and YBa2Cu3Ox, and possibly to MgB2, recently discovered to superconduct at 39 K. Crystal structure and material anisotropy place fundamental restrictions on their properties, especially in polycrystalline form. So far, power applications have followed a largely empirical, twin-track approach of conductor development and construction of prototype devices. The feasibility of superconducting power cables, magnetic energy-storage devices, transformers, fault current limiters and motors, largely using (Bi,Pb)2Sr2Ca2Cu3Ox conductor, is proven. Widespread applications now depend significantly on cost-effective resolution of fundamental materials and fabrication issues, which control the production of low-cost, high-performance conductors of these remarkable compounds.
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Affiliation(s)
- D Larbalestier
- Applied Superconductivity Center, Department of Materials Science and Engineering, University of Wisconsin, Madison, Wisconsin 53706, USA.
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26
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Kim HJ, Kang WN, Choi EM, Kim MS, Kim KH, Lee SI. High current-carrying capability in c-axis-oriented superconducting MgB2 thin films. PHYSICAL REVIEW LETTERS 2001; 87:087002. [PMID: 11497972 DOI: 10.1103/physrevlett.87.087002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2001] [Indexed: 05/23/2023]
Abstract
In high-quality c-axis-oriented MgB2 thin films, we observed high critical current densities ( J(c)) of approximately 16 MA/cm(2) at 15 K under self-fields comparable to those of cuprate high-temperature superconductors. The extrapolated value of J(c) at 5 K was estimated to be approximately 40 MA/cm(2). For a magnetic field of 5 T, a J(c) of approximately 0.1 MA/cm(2) was detected at 15 K, suggesting that this compound would be a very promising candidate for practical applications at high temperature and lower power consumption. The vortex-glass phase is considered to be a possible explanation for the observed high current-carrying capability.
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Affiliation(s)
- H J Kim
- National Creative Research Initiative Center for Superconductivity, Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
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27
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de Lima OF, Ribeiro RA, Avila MA, Cardoso CA, Coelho AA. Anisotropic superconducting properties of aligned MgB(2) crystallites. PHYSICAL REVIEW LETTERS 2001; 86:5974-5977. [PMID: 11415407 DOI: 10.1103/physrevlett.86.5974] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2001] [Indexed: 05/23/2023]
Abstract
Samples of aligned MgB(2) crystallites have been prepared, allowing for the first time the direct identification of an upper critical field anisotropy H(ab)(c2)/H(c)(c2) = xi(ab)/xi(c) approximately 1.7, with xi(o,ab) approximately 70 A, xi(o,c) approximately 40 A, and a mass anisotropy ratio m(ab)/m(c) approximately 0.3. A ferromagnetic background signal was identified, possibly related to the raw materials purity.
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Affiliation(s)
- O F de Lima
- Instituto de Física Gleb Wataghin, UNICAMP, 13083-970, Campinas, SP, Brazil
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28
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Eom CB, Lee MK, Choi JH, Belenky LJ, Song X, Cooley LD, Naus MT, Patnaik S, Jiang J, Rikel M, Polyanskii A, Gurevich A, Cai XY, Bu SD, Babcock SE, Hellstrom EE, Larbalestier DC, Rogado N, Regan KA, Hayward MA, He T, Slusky JS, Inumaru K, Haas MK, Cava RJ. High critical current density and enhanced irreversibility field in superconducting MgB2 thin films. Nature 2001; 411:558-60. [PMID: 11385563 DOI: 10.1038/35079018] [Citation(s) in RCA: 442] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The discovery of superconductivity at 39 K in magnesium diboride offers the possibility of a new class of low-cost, high-performance superconducting materials for magnets and electronic applications. This compound has twice the transition temperature of Nb3Sn and four times that of Nb-Ti alloy, and the vital prerequisite of strongly linked current flow has already been demonstrated. One possible drawback, however, is that the magnetic field at which superconductivity is destroyed is modest. Furthermore, the field which limits the range of practical applications-the irreversibility field H*(T)-is approximately 7 T at liquid helium temperature (4.2 K), significantly lower than about 10 T for Nb-Ti (ref. 6) and approximately 20 T for Nb3Sn (ref. 7). Here we show that MgB2 thin films that are alloyed with oxygen can exhibit a much steeper temperature dependence of H*(T) than is observed in bulk materials, yielding an H* value at 4.2 K greater than 14 T. In addition, very high critical current densities at 4.2 K are achieved: 1 MA cm-2 at 1 T and 105 A cm-2 at 10 T. These results demonstrate that MgB2 has potential for high-field superconducting applications.
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Affiliation(s)
- C B Eom
- Department of Materials Science and Engineering, University of Wisconsin, Madison, Wisconsin 53706, USA.
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29
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30
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Jin S, Mavoori H, Bower C, van Dover RB. High critical currents in iron-clad superconducting MgB2 wires. Nature 2001; 411:563-5. [PMID: 11385565 DOI: 10.1038/35079030] [Citation(s) in RCA: 399] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Technically useful bulk superconductors must have high transport critical current densities, Jc, at operating temperatures. They also require a normal metal cladding to provide parallel electrical conduction, thermal stabilization, and mechanical protection of the generally brittle superconductor cores. The recent discovery of superconductivity at 39 K in magnesium diboride (MgB2) presents a new possibility for significant bulk applications, but many critical issues relevant for practical wires remain unresolved. In particular, MgB2 is mechanically hard and brittle and therefore not amenable to drawing into the desired fine-wire geometry. Even the synthesis of moderately dense, bulk MgB2 attaining 39 K superconductivity is a challenge because of the volatility and reactivity of magnesium. Here we report the successful fabrication of dense, metal-clad superconducting MgB2 wires, and demonstrate a transport Jc in excess of 85,000 A cm-2 at 4.2 K. Our iron-clad fabrication technique takes place at ambient pressure, yet produces dense MgB2 with little loss of stoichiometry. While searching for a suitable cladding material, we found that other materials dramatically reduced the critical current, showing that although MgB2 itself does not show the 'weak-link' effect characteristic of the high-Tc superconductors, contamination does result in weak-link-like behaviour.
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Affiliation(s)
- S Jin
- Agere Systems/Lucent Technologies, Murray Hill, New Jersey 07974, USA.
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31
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Bugoslavsky Y, Cohen LF, Perkins GK, Polichetti M, Tate TJ, Gwilliam R, Caplin AD. Enhancement of the high-magnetic-field critical current density of superconducting MgB2 by proton irradiation. Nature 2001; 411:561-3. [PMID: 11385564 DOI: 10.1038/35079024] [Citation(s) in RCA: 267] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Magnesium diboride, MgB2, has a relatively high superconducting transition temperature, placing it between the families of low- and high-temperature (copper oxide based) superconductors. Supercurrent flow in MgB2 is unhindered by grain boundaries, making it potentially attractive for technological applications in the temperature range 20-30 K. But in the bulk material, the critical current density (Jc) drops rapidly with increasing magnetic field strength. The magnitude and field dependence of the critical current are related to the presence of structural defects that can 'pin' the quantized magnetic vortices that permeate the material, and a lack of natural defects in MgB2 may be responsible for the rapid decline of Jc with increasing field strength. Here we show that modest levels of atomic disorder induced by proton irradiation enhance the pinning of vortices, thereby significantly increasing Jc at high field strengths. We anticipate that either chemical doping or mechanical processing should generate similar levels of disorder, and so achieve performance that is technologically attractive in an economically viable way.
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Affiliation(s)
- Y Bugoslavsky
- Centre for High Temperature Superconductivity, Blackett Laboratory, Imperial College, London SW7 2BZ, UK.
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32
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Kang WN, Kim HJ, Choi EM, Jung CU, Lee SI. MgB2 superconducting thin films with a transition temperature of 39 kelvin. Science 2001; 292:1521-3. [PMID: 11303089 DOI: 10.1126/science.1060822] [Citation(s) in RCA: 393] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We fabricated high-quality c axis-oriented epitaxial MgB2 thin films using a pulsed laser deposition technique. The thin films grown on (1 i 0 2) Al2O3 substrates have a transition temperature of 39 kelvin. The critical current density in zero field is approximately 6 x 10(6) amperes per cubic centimeter at 5 kelvin and approximately 3 x 10(5) amperes per cubic centimeter at 35 kelvin, which suggests that this compound has potential for electronic device applications, such as microwave devices and superconducting quantum interference devices. For the films deposited on Al2O3, x-ray diffraction patterns indicate a highly c axis-oriented crystal structure perpendicular to the substrate surface.
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Affiliation(s)
- W N Kang
- National Creative Research Initiative Center for Superconductivity, Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea.
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33
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Karapetrov G, Iavarone M, Kwok WK, Crabtree GW, Hinks DG. Scanning tunneling spectroscopy in MgB2. PHYSICAL REVIEW LETTERS 2001; 86:4374-4377. [PMID: 11328178 DOI: 10.1103/physrevlett.86.4374] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2001] [Indexed: 05/23/2023]
Abstract
We present scanning tunneling microscopy measurements of the surface of superconducting MgB2 with a critical temperature of 39 K. In zero magnetic field the conductance spectra can be analyzed in terms of the standard BCS theory with a smearing parameter gamma. The value of the superconducting gap is 5 meV at 4.2 K, with no experimentally significant variation across the surface of the sample. The temperature dependence of the gap follows the BCS form, fully consistent with phonon-mediated superconductivity in this novel superconductor. The application of a magnetic field induces strong pair breaking as seen in the conductance spectra in fields up to 6 T.
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Affiliation(s)
- G Karapetrov
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
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34
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Bugoslavsky Y, Perkins GK, Qi X, Cohen LF, Caplin AD. Vortex dynamics in superconducting MgB2 and prospects for applications. Nature 2001; 410:563-5. [PMID: 11279489 DOI: 10.1038/35069029] [Citation(s) in RCA: 185] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The recently discovered superconductor magnesium diboride, MgB2, has a transition temperature, Tc, approaching 40 K, placing it intermediate between the families of low- and high-temperature superconductors. In practical applications, superconductors are permeated by quantized vortices of magnetic flux. When a supercurrent flows, there is dissipation of energy unless these vortices are 'pinned' in some way, and so inhibited from moving under the influence of the Lorentz force. Such vortex motion ultimately determines the critical current density, Jc, which the superconductor can support. Vortex behaviour has proved to be more complicated in high-temperature superconductors than in low-temperature superconductors and, although this has stimulated extensive theoretical and experimental research, it has also impeded applications. Here we describe the vortex behaviour in MgB2, as reflected in Jc and in the vortex creep rate, S, the latter being a measure of how fast the 'persistent' supercurrents decay. Our results show that naturally occurring grain boundaries are highly transparent to supercurrents, a desirable property which contrasts with the behaviour of the high-temperature superconductors. On the other hand, we observe a steep, practically deleterious decline in Jc with increasing magnetic field, which is likely to reflect the high degree of crystalline perfection in our samples, and hence a low vortex pinning energy.
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Affiliation(s)
- Y Bugoslavsky
- Centre for High Temperature Superconductivity, Blackett Laboratory, Imperial College, London, UK.
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35
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Ball P. Superconductivity hots up. Nature 2001. [DOI: 10.1038/conference010315-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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