A Trapped Magnetic Field Over 5 T in Doped Bulk MgB2 Obtained by ex-situ Spark Plasma Sintering
Résumé
The advantage of the very low density of MgB2 bulk samples must be taken into consideration and, the generation of strong magnetic flux densities using MgB2 should be investigated. It was shown in [1] that the organometallic addition to MgB2 of Ge2C6H10O7 greatly enhances the pinning forces, leading to higher critical current density Jc and irreversibility field Hirr in the added sample compared to pristine MgB2, Fig. 1(a). All the samples were produced by ex-situ Spark Plasma Sintering. In this contribution, we have studied the trapped magnetic field in samples of 20 mm in diameter and 4 mm high, but also in a stack of 6 of these samples leading to a total height of 24 mm. Field Cooling experiments were carried out at temperatures from 12 K to 30 K. The trapped magnetic field inside the stack of 6 samples and at the center of the surface are reported, Fig. 1(b). According to the obtained values of trapped magnetic field greater than 5 T at 12 K, and 4 T at 20 K, to their very low density and to their ease of manufacturing, doped bulk MgB2 with Ge2C6H10O7 are really interesting for the intended applications.
Fig. 1: Irreversibility field Hirr of a pristine MgB2 and of a doped MgB2 (a), and the measured trapped magnetic field at the center of the surface of a stack of 6 samples of 20 mm diameter & 4 mm high (b).
References
1. D. Batalu, G. Aldica, S. Popa, L. Miu, M. Enculescu, R. F. Negrea, I. Pasuk, and P. Badica, High magnetic field enhancement of the critical current density by Ge, GeO2 and Ge2C6H10O7 additions to MgB2, Scripta Mater. 82 61 (2014).
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