Fabrication of MgB₂ Bulk Magnets with High Critical Currents

Abstract:

We report on the fabrication and characterization of disk-shaped bulk MgB₂ superconductors with high performance as superconducting bulk magnets. Several samples of diameters 20 mm, 30 mm and 40 mm were fabricated using a solid state reaction in pure Ar atmosphere at 775°C for 3h. The magnetization measurements confirmed that all the samples exhibited a sharp superconducting transition with T_c (onset) at around 38.5 K. The samples showed respective critical current density (J_c) values of 176 kA cm^-2 and 55 kA cm^-2 at 20 K in self field and 1T. The J_c values increased further to 250 kA cm^-2 and 100 kA cm^-2 with decreasing temperature down to 10 K. MgB₂ samples 20 mm and 30 mm in diameter and 7 mm in thickness exhibited trapped field values of 1.15 T and 1.3 T at 25 K, respectively. Microstructural observations with scanning electron microscopy (SEM) revealed that the samples are highly porous. And hence, continuing development of large-sized bulk MgB₂ with higher density will lead to promising industrial applications.

• Periodical: Advances in Science and Technology (Volume 95)
• Pages: 196-201
• DOI: https://doi.org/10.4028/www.scientific.net/AST.95.196
• Online since: October 2014
• Authors: Miryala Muralidhar*, Kazuo Inoue, Michael R. Koblischka, Masato Murakami
• Keywords: Critical Current Density (J_c), MgB₂, Microstructure Analysis, Trapped Field Magnets

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