Prospects for Improving the Intrinsic and Extrinsic Properties of Magnesium Diboride Superconducting Strands

Abstract

The magnetic and transport properties of magnesium diboride films represent performance goals yet to be attained by powder-processed bulk samples and conductors. Such performance limits are still out of the reach of even the best magnesium diboride magnet wire. In discussing the present status and prospects for improving the performance of powder-based wire we focus attention on (1) the intrinsic (intragrain) superconducting properties of magnesium diboride, Hc2 and flux pinning, (2) factors that control the efficiency with which current is transported from grain-to-grain in the conductor, an extrinsic (intergrain) property. With regard to Item-(1), the role of dopants in Hc2 enhancement is discussed and examples presented. On the other hand their roles in increasing Jc, both via Hc2 enhancement as well as direct fluxoid/pining-center interaction, are discussed and a comprehensive survey of Hc2 dopants and flux-pinning additives is presented. Current transport through the powder-processed wire (an extrinsic property) is partially blocked by the inherent granularity of the material itself and the chemical or other properties of the intergrain surfaces. These and other such results indicate that in many cases less than 15% of the conductor's cross sectional area is able to carry transport current. It is pointed out that densification in association with the elimination of grain-boundary blocking phases would yield five-to ten-fold increases in Jc in relevant regimes, enabling the performance of magnesium diboride in selected applications to compete with that of Nb-Sn.

References in corpus (47)

• Superconductivity of metallic boron in MgB_2
• Beyond Eliashberg superconductivity in MgB2: anharmonicity, two-phonon scattering, and multiple gaps
• Strongly linked current flow in polycrystalline forms of the new superconductor MgB2
• Boron Isotope Effect in Superconducting MgB${}_2$
• Superconductivity of MgB2: Covalent Bonds Driven Metallic
• Enhancement of the critical current density and flux pinning of MgB2 superconductor by nanoparticle SiC doping
• Enhancement of the upper critical field by nonmagnetic impurities in dirty two-gap superconductors
• Electron-phonon interaction in the normal and superconducting states of MgB2
• Thin Film Magnesium Boride Superconductor with Very High Critical Current Density and Enhanced Irreversibility Field
• Phonon dispersion and electron-phonon coupling in MgB_2 and AlB_2
• First-Principles Calculation of the Superconducting Transition in MgB2 within the Anisotropic Eliashberg Formalism
• Specific heat in the superconducting and normal state (2-300 K, 0-16 Teslas), and magnetic susceptibility of the 38-K superconductor MgB2: evidence for a multicomponent gap
• Two-gap superconductivity in MgB${}_2$: clean or dirty?
• Multiband model for tunneling in MgB2 junctions
• Very high upper critical fields in MgB2 produced by selective tuning of impurity scattering
• High-field superconductivity in alloyed MgB2 thin films
• Limits of the upper critical field in dirty two-gap superconductors
• Carbon doping of superconducting magnesium diboride
• Nanoscale-SiC doping for enhancing Jc and Hc2 in the Superconducting MgB2
• Effect of nano-carbon particle doping on the flux pinning properties of MgB2 superconductor
• Strong Electron-Phonon Coupling in Superconducting MgB${}_2$: A Specific Heat Study
• Improved critical current densities in B4C doped MgB2 based wires
• The different development of the anisotropic upper critical field in MgB2 by aluminum and carbon doping
• Strong Pinning Enhancement in MgB2 Using Very Small Dy2O3 Additions
• Doping Effect of Nano-Diamond on Superconductivity and Flux Pinning in MgB2
• Critical Current Density and Resistivity of MgB2 Films
• A New Approach for the Fabrication of MgB2 Superconducting Tape with Large In-field Transport Critical Current Density
• Carbon-substitution dependent multiple superconducting gap of MgB${}_2$: a "sub-meV" resolution photoemission study
• Improved Irreversibility Behaviour and Critical Current Density in MgB2-Diamond Nanocomposites
• Effect of two bands on critical fields in MgB2 thin films with various resistivity values
• Effect of Nano Scale Fe Doping on Superconducting Properties of MgB2
• Growth of superconducting MgB2 thin films via postannealing techniques
• Improvement of critical current density in Fe-sheathed MgB2 tapes by ZrSi2, ZrB2 and WSi2 doping
• Irreversibility Field and Flux Pinning in MgB2 with and Without SiC Additions
• Enhancement of in-field Jc in MgB2/Fe wire using single and multi-walled nanotubes
• Pressure dependence of the upper critical field of MgB2 and of YNi2B2C
• High critical current density and improved flux pinning in bulk MgB2 synthesized by Ag addition
• Influence of carbon substitution on the heat transport in single crystalline MgB2
• Increases in the Irreversibility Field and the Upper Critical Field of Bulk MgB2 by ZrB2 Addition
• Disorder induced collapse of the electron phonon coupling in MgB${}_2$ observed by Raman Spectroscopy
• Upper Critical Fields up to 60T in Dirty Magnesium Diboride Thin Films
• On Heavy Carbon Doping of MgB${}_2$
• Effect of La Doping on Microstructure and Critical Current Density of MgB2
• Titanium additions to MgB2 conductors
• Correlated vortex pinning in Si-nanoparticle doped MgB2
• Improved critical current densities in MgB2 tapes with ZrB2 doping
• Off-axis MgB2 films using an in situ annealing pulsed laser deposition method

Cited by in corpus (15)

• Strong enhancement of Jc in binary and alloyed in-situ MgB2 wires by a new approach: Cold high pressure densification
• The critical current density of advanced internal-Mg-diffusion-processed MgB2 wires
• Critical Current Density and n-values of MgB2 Strands over a Wide Range of Temperatures and Fields
• Drawing induced texture and the evolution of superconductive properties with heat treatment time in powder-in-tube in-situ processed MgB2 strands
• Strongly connected ex-situ MgB2 polycrystalline bulks fabricated by solid-state self-sintering
• Grain boundary characteristics of Fe-based superconductors
• Towards the Realization of Higher Connectivity in MgB2 Conductors: In-situ or Sintered Ex-situ?
• Enhanced higher temperature (20-30 K) transport properties and irreversibility field in nano-Dy2O3 doped advanced internal Mg infiltration processed MgB2 composites
• Study of the MgB2 grain size role in ex-situ multifilamentary wires with thin filaments
• Doping Effect and Flux Pinning Mechanism of Nano-SiC Additions in MgB2 Strands
• Anisotropic Connectivity and its Influence on Critical Current Densities, Irreversibility Fields, and Flux Creep in In-Situ-Processed MgB2 Strands
• Tailored joint fabrication process derived ultra-low resistance MgB2 superconducting joint
• Development of Doped MgB2 Wires and Tapes for Practical Applications
• Influence of Strand Design, Boron Type, and Carbon Doping Method on the Transport Properties of Powder-in-Tube MgB2-XCX Strands
• Thermal conductivity and stability of commercial MgB${}_2$ conductors