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Engineering Properties of Superconducting Materials (Second Volume)

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Quantum Materials".

Deadline for manuscript submissions: closed (20 November 2022) | Viewed by 9346

Special Issue Editor

Electrical Engineering Department, Cambridge University, Cambridge, UK
Interests: high field magnets; flux pumping; AC losses; power applications of superconductivity (SFCLS, SMES, turbines, motors, cables)

Special Issue Information

Dear Colleagues,

The search for clean energy sources has been a fundamental key in materials research. The development of superconducting materials attracts significant scientific and technological resources toward achieving low costs, as well as suitable and profitable power generation, storage, distribution, and transmission. In addition, superconducting electronics can provide devices and circuits with properties not obtainable by any other known technology; i.e., very low loss, zero frequency-dispersion signal transmission lines, very high Q-value resonators and filters, and quantum limited electromagnetic sensors.

All of these advances require high-quality superconducting materials, and in recent years, great strides have been made to improve the properties of existing materials, as well as the continuing discovery of new systems and materials, such as the Pnictides.

In 1911, Heike Kamerlingh Onnes discovered superconductivity in mercury by cooling it down to a frosty 4.2 K (–268.95 °C). Since then, it has been the Holy Grail of material scientists to achieve this transition—from a normal to a superconducting state—at room temperature (above 273.15 K or 0 °C). The hope of finding a room-temperature superconductor (RTS) bloomed after physicists discovered high-temperature superconductivity (HTS) in the 1980s and 1990s in a class of ceramic materials called cuprates. These are characterized by the presence of interleaving copper-oxide layers. Their transition temperature—also known as critical temperature (Tc)—was significantly higher than those of conventional metallic superconductors discovered decades earlier.

From 1911 and until the discovery of superconductivity in Lanthanum Barium Cuprate in 1986, there was a steady rate of discovery of new materials including Nb3Sn and NbTi (important in NMR, MRI and high field magnets). However, the discovery that really opened the R&D floodgates was of superconductivity in an yttrium–barium–copper–oxide (YBCO) system, in which Tc was 93 K. Soon, scientists were investigating a wide variety of such systems, including bismuth- and mercury-based compounds. More recently, a range of materials which are distinct from the cuprates, such as MgB2 and iron-based superconductors, have been discovered.

There is a continuous drive toward higher and higher transition temperatures, and to date, the highest superconducting Tc achieved and confirmed is 203 K in 2015. However, this was not in a high-Tc cuprate system but in hydrogen–sulfide (H2S) subjected to very high pressure: about 1.5 million atmospheres. The highest Tc achieved in a cuprate material was in 1993 at 138 K, in a mercury–barium–calcium–copper–oxide system at atmospheric pressure. The Tc increased to 164 K when the pressure was increased to ~296,000 atmospheres.

From an engineering point of view, although higher transition temperatures are desirable, of greater interest is the development of the engineering properties of the materials. Consequently, this Special Issue aims to focus on the development of superconductors, in a materials relationship framework, and specifically to collate their engineering properties. Topics of interest include but are not limited to the following topics:

  • Coated conductors, especially critical current versus field and temperature;
  • Iron-based superconductors;
  • Superconductivity in unconventional materials (e.g., graphene);
  • Flux pinning mechanisms;
  • AC losses;
  • Normal zone propagation velocity;
  • Materials and process for high-throughput fabrication.

Dr. Tim Coombs
Guest Editor

Manuscript Submission Information

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Keywords

  • superconductors
  • engineering
  • power
  • critical current
  • critical temperature

Published Papers (5 papers)

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Research

16 pages, 2702 KiB  
Article
Inhomogeneous Superconductivity Onset in FeSe Studied by Transport Properties
by Pavel D. Grigoriev, Vladislav D. Kochev, Andrey P. Orlov, Aleksei V. Frolov and Alexander A. Sinchenko
Materials 2023, 16(5), 1840; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16051840 - 23 Feb 2023
Cited by 2 | Viewed by 1155
Abstract
Heterogeneous superconductivity onset is a common phenomenon in high-Tc superconductors of both the cuprate and iron-based families. It is manifested by a fairly wide transition from the metallic to zero-resistance states. Usually, in these strongly anisotropic materials, superconductivity (SC) first appears as [...] Read more.
Heterogeneous superconductivity onset is a common phenomenon in high-Tc superconductors of both the cuprate and iron-based families. It is manifested by a fairly wide transition from the metallic to zero-resistance states. Usually, in these strongly anisotropic materials, superconductivity (SC) first appears as isolated domains. This leads to anisotropic excess conductivity above Tc, and the transport measurements provide valuable information about the SC domain structure deep within the sample. In bulk samples, this anisotropic SC onset gives an approximate average shape of SC grains, while in thin samples, it also indicates the average size of SC grains. In this work, both interlayer and intralayer resistivity were measured as a function of temperature in FeSe samples of various thicknesses. To measure the interlayer resistivity, FeSe mesa structures oriented across the layers were fabricated using FIB. As the sample thickness decreases, a significant increase in superconducting transition temperature Tc is observed: Tc raises from 8 K in bulk material to 12 K in microbridges of thickness ∼40 nm. We applied analytical and numerical calculations to analyze these and earlier data and find the aspect ratio and size of the SC domains in FeSe consistent with our resistivity and diamagnetic response measurements. We propose a simple and fairly accurate method for estimating the aspect ratio of SC domains from Tc anisotropy in samples of various small thicknesses. The relationship between nematic and superconducting domains in FeSe is discussed. We also generalize the analytical formulas for conductivity in heterogeneous anisotropic superconductors to the case of elongated SC domains of two perpendicular orientations with equal volume fractions, corresponding to the nematic domain structure in various Fe-based superconductors. Full article
(This article belongs to the Special Issue Engineering Properties of Superconducting Materials (Second Volume))
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9 pages, 4904 KiB  
Article
Theoretical Study of Dynamical and Electronic Properties of Noncentrosymmetric Superconductor NbReSi
by Surajit Basak and Andrzej Ptok
Materials 2023, 16(1), 78; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16010078 - 21 Dec 2022
Cited by 2 | Viewed by 1559
Abstract
The noncentrosymmetric NbReSi superconductor with Tc6.5 K is characterized by the relatively large upper critical magnetic field. Its multigap features were observed experimentally. Recent studies suggested the realization of P6¯2m or Ima2 symmetry. We discuss the dynamical [...] Read more.
The noncentrosymmetric NbReSi superconductor with Tc6.5 K is characterized by the relatively large upper critical magnetic field. Its multigap features were observed experimentally. Recent studies suggested the realization of P6¯2m or Ima2 symmetry. We discuss the dynamical properties of both symmetries (e.g., phonon spectra). In this paper, using the ab initio techniques, we clarify this ambiguity, and conclude that the Ima2 symmetry is unstable, and P6¯2m should be realized. The P6¯2m symmetry is also stable in the presence of external hydrostatic pressure. We show that NbReSi with the P6¯2m symmetry should host phonon surface states for (100) and (110) surfaces. Additionally, we discuss the main electronic properties of the system with the stable symmetry. Full article
(This article belongs to the Special Issue Engineering Properties of Superconducting Materials (Second Volume))
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11 pages, 2578 KiB  
Article
Sintering Nano-Silver Paste by Resistive Joule Heating Process for 2G HTS Tape Joints
by Chia-Ming Yang, Yu-Chuan Chang, Chi-Lei Chang and In-Gann Chen
Materials 2022, 15(4), 1571; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15041571 - 19 Feb 2022
Cited by 3 | Viewed by 2049
Abstract
Developing a joining technology for 2G HTS tapes without significantly reducing their superconducting property is crucial for numerous applications (MRI, motor/generator, power transmission, etc.). In this study, low sintering temperature (~230 °C) nano-silver paste was used as solder to join two 2G HTS [...] Read more.
Developing a joining technology for 2G HTS tapes without significantly reducing their superconducting property is crucial for numerous applications (MRI, motor/generator, power transmission, etc.). In this study, low sintering temperature (~230 °C) nano-silver paste was used as solder to join two 2G HTS tapes. In addition, two heating methods, i.e., furnace heating (heat flux outside-in) and resistive Joule heating (heat flux inside-out), were studied. This study indicates that the heat flux from internal by resistive Joule heating method shows less deteriorating impact to the 2G RE-Ba-Cu-O tape (RE: rare earth element) during the sintering process with the best specific resistance of 0.074 μΩ∙cm2 and Ic retention percentage of 99% (i.e., Ic reduced from 100 A before joining to 99 A after joining). This study indicates that nano-silver paste together with resistive Joule heating can possibly be used as soldering materials to join 2G HTS tapes. Full article
(This article belongs to the Special Issue Engineering Properties of Superconducting Materials (Second Volume))
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21 pages, 3383 KiB  
Article
Critical State Theory for the Magnetic Coupling between Soft Ferromagnetic Materials and Type-II Superconductors
by Muhammad U. Fareed and Harold S. Ruiz
Materials 2021, 14(20), 6204; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14206204 - 19 Oct 2021
Cited by 2 | Viewed by 1992
Abstract
Improving our understanding of the physical coupling between type-II superconductors (SC) and soft ferromagnetic materials (SFM) is the root for progressing to the application of SC-SFM metastructures in scenarios such as magnetic cloaking, magnetic shielding, and power transmission systems. However, in the latter, [...] Read more.
Improving our understanding of the physical coupling between type-II superconductors (SC) and soft ferromagnetic materials (SFM) is the root for progressing to the application of SC-SFM metastructures in scenarios such as magnetic cloaking, magnetic shielding, and power transmission systems. However, in the latter, some intriguing and yet unexplained phenomena occurred, such as a noticeable rise in the SC energy losses, and a local but not isotropic deformation of its magnetic flux density. These phenomena, which are in apparent contradiction with the most fundamental theory of electromagnetism for superconductivity, that is, the critical state theory (CST), have remained unexplained for about 20 years, given the acceptance of the controversial and yet paradigmatic existence of the so-called overcritical current densities. Therefore, aiming to resolve these long-standing problems, we extended the CST by incorporating a semi-analytical model for cylindrical monocore SC-SFM heterostructures, setting the standards for its validation with a variational approach of multipole functionals for the magnetic coupling between Sc and SFM materials. It is accompanied by a comprehensive numerical study for SFM sheaths of arbitrary dimensions and magnetic relative permeabilities μr, ranging from μr=5 (NiZn ferrites) to μr = 350,000 (pure Iron), showing how the AC-losses of the SC-SFM metastructure radically changes as a function of the SC and the SFM radius for μr100. Our numerical technique and simulations also revealed a good qualitative agreement with the magneto optical imaging observations that were questioning the CST validness, proving therefore that the reported phenomena for self-field SC-SFM heterostructures can be understood without including the ansatz of overcritical currents. Full article
(This article belongs to the Special Issue Engineering Properties of Superconducting Materials (Second Volume))
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14 pages, 1671 KiB  
Article
Modeling Superconducting Critical Temperature of 122-Iron-Based Pnictide Intermetallic Superconductor Using a Hybrid Intelligent Computational Method
by Oluwatobi Akomolafe, Taoreed O. Owolabi, Mohd Amiruddin Abd Rahman, Mohd Mustafa Awang Kechik, Mohd Najib Mohd Yasin and Miloud Souiyah
Materials 2021, 14(16), 4604; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14164604 - 16 Aug 2021
Cited by 12 | Viewed by 1706
Abstract
Structural transformation and magnetic ordering interplays for emergence as well as suppression of superconductivity in 122-iron-based superconducting materials. Electron and hole doping play a vital role in structural transition and magnetism suppression and ultimately enhance the room pressure superconducting critical temperature of the [...] Read more.
Structural transformation and magnetic ordering interplays for emergence as well as suppression of superconductivity in 122-iron-based superconducting materials. Electron and hole doping play a vital role in structural transition and magnetism suppression and ultimately enhance the room pressure superconducting critical temperature of the compound. This work models the superconducting critical temperature of 122-iron-based superconductor using tetragonal to orthorhombic lattice (LAT) structural transformation during low-temperature cooling and ionic radii of the dopants as descriptors through hybridization of support vector regression (SVR) intelligent algorithm with particle swarm (PS) parameter optimization method. The developed PS-SVR-RAD model, which utilizes ionic radii (RAD) and the concentrations of dopants as descriptors, shows better performance over the developed PS-SVR-LAT model that employs lattice parameters emanated from structural transformation as descriptors. Using the root mean square error (RMSE), coefficient of correlation (CC) and mean absolute error as performance measuring criteria, the developed PS-SVR-RAD model performs better than the PS-SVR-LAT model with performance improvement of 15.28, 7.62 and 72.12%, on the basis of RMSE, CC and Mean Absolute Error (MAE), respectively. Among the merits of the developed PS-SVR-RAD model over the PS-SVR-LAT model is the possibility of electrons and holes doping from four different dopants, better performance and ease of model development at relatively low cost since the descriptors are easily fetched ionic radii. The developed intelligent models in this work would definitely facilitate quick and precise determination of critical transition temperature of 122-iron-based superconductor for desired applications at low cost with experimental stress circumvention. Full article
(This article belongs to the Special Issue Engineering Properties of Superconducting Materials (Second Volume))
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