Microstructure and critical current density in MgB2 bulk made of 4.5 wt% carbon-coated boron

29th International Symposium on Superconductivity

Higuchi, M.^1 ; Muralidhar, M.^1 ; Jirsa, M.^2 ; Murakami, M.^1

Superconducting Material Laboratory, Graduate School of Science and Engineering, Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo

135-8546, Japan^1

EInstitute of Physics CAS, Na Slovance 2, Praha 8

CZ-18221, Czech Republic^2

关键词: All positions;    Carbon-coated;    Carbon-encapsulated;    DC magnetization;    MgB2 superconductor;    SEM analysis;    Superconducting performance;    Superconducting transitions;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/871/1/012059/pdf
DOI  :  10.1088/1742-6596/871/1/012059

来源: IOP

【 摘 要 】

Superconducting performance and its uniformity was studied in the single-step sintered MgB2bulk prepared with 4.5 wt% of carbon in the carbon-encapsulated boron. The 20 mm in diameter MgB2pellet was cut into several pieces from bottom to top and the microstructure, superconducting transition temperature (Tconset), and critical current density at 20 K were studied. DC magnetization measurements showed a sharp superconducting transition with onset Tcat around 35.5 K in all positions. SEM analysis indicated a dispersion of grains between 200 and 300 nm in size, as the main pinning medium in this MgB2superconductors. The critical current density at 20 K was quite uniform, around 330 kA/cm2and 200 kA/cm2at self-field and 1 T, respectively, for all measured positions. The results indicate that the carbon-encapsulated boron is very promising for production of high quality bulk MgB2material for various industrial applications.