A series of disk-shaped, bulk MgB2 superconductors (sample diameter 20 mm, reaction temperatures ranging between 750 °C and 950 °C) was prepared 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, Fp = jc × B, was performed. The different scaling behavior of the samples prepared at low- and high-reaction temperatures is discussed, considering the achieved microstructures.
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