2011/08/31 by G Z Li, Y Yang, Y. Yang +6
Materials Science · Physics and Astronomy · #Condensed matter physics #Critical current #Current (fluid) #Iron-based superconductors research #Materials science #Physics #Physics of Superconductivity and Magnetism #Range (aeronautics) #Superconductivity #Superconductivity in MgB2 and Alloys #Thermodynamics #cond-mat.supr-con
paper · pdf · doi:10.1088/0953-2048/25/2/025001
published as Supercond. Sci. Technol. 25 (2012) 025001 · 34 pages, 7 figures
arxiv created 2011/11/24 · openalex publication_date 2011/12/22 · arxiv updated 2015/05/29 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Transport measurements of critical current density, J ct , in monocore powder-in-tube MgB 2 strands have been carried out at temperatures, T , of from 4.2 to 40 K, and in transverse fields, B , of up to 14 T. Processing methods used were conventional continuous tube forming/filling (CTFF) and internal magnesium diffusion (IMD). Strands with several powder compositions were measured, including binary (undoped) MgB 2 , 2% carbon doped MgB 2 , and 3% carbon doped MgB 2 . Magnetization loops ( M – B ) were also measured, and magnetic critical current density, J cm , values extracted from them. The transport, J ct ( B ) and magnetic, J cm ( B ), critical current densities were compared. Also studied was the influence of doping on the resistively measured irreversibility field, B irr , and upper critical field, B c2 . Critical current densities, J ct , and n -values were extracted from transport measurements and were found to be universally related (for all B and T ) according to in which m = 0.52 ± 0.11. Likewise n was found to be related to B according to n ∝ B − p with a T -dependent p in the range of about 0.08–0.21. Further analysis of the field ( B ) and temperature ( T ) dependences of n -value resulted in an expression that enabled n ( B , T ), for all B and T , to be estimated for a given strand based on the results of transport J ct ( B ) measurements made at one arbitrarily chosen temperature.