Development of MgB₂-Based Bulk Supermagnets

Abstract

Abstract-A series of disk-shaped, bulk MgB 2 superconductors (sample diameter 20 mm, reaction temperatures ranging between 750 °C and 950 °C) was prepared in order to improve the performance for superconducting supermagnets. These samples were characterized by magnetic and electric measurements in fields up to 7 T and at various temperatures 10 K < T < 35 K. The irreversibility lines, the current densities, the resistance and the achievable trapped fields were determined. To analyze the data, a scaling of the flux pinning forces, F p = j c × B, was performed. The different scaling behavior of the samples prepared at low and high reaction temperatures is discussed considering the achieved microstructures.Index Terms-MgB 2 , supermagnets, trapped fields, flux pinning forces.

Optimization of sintering conditions in bulk MgB2 material for improvement of critical current density

“…The scaling works well for all samples irrespective of the sintering time, with a peak located at h 0~0 .23, which suggests that the dominant pinning centers are extended normal-conducting defects. Similar values are obtained in our earlier results as well as in the literature for small MgB 2 samples [41,42]. In Fig.…”

Modelling of Critical Current Density of Sintered Ag Added Bulk MgB2

“…The scaling works efficiently for all samples irrespective of Ag with a peak located at h 0 ≈ 0.21 which suggests that dominant pinning centers were extended with normal-conducting defects. Similar values were obtained in earlier reports presented in the literature for small MgB 2 samples [20,26,27]. For instance, the peak position around h max = 0.2 suggests that grain-boundary pinning were active for both set of samples.…”

Analysis of the microstructure of bulk MgB2 using TEM, EBSD and t‐EBSD

“…This is clearly in contrast to other sintered, polycrystalline MgB 2 samples as investigated in Koblischka et al . (). In the present sample, the dominant flux pinning is provided by the GBs, and the MgB 4 and MgO particles do not play a role as expected from the EBSD maps.…”