MgB with addition of SbO obtained by spark plasma sintering technique.

Superconducting bulks of MgB with addition of SbO and Sb with different stoichiometric compositions ((MgB) + (SbO), x = 0.0025, 0.005, 0.015, and (MgB) + (Sb), y = 0.01) were obtained by the Spark Plasma Sintering (SPS) technique. All added samples have high density, above 95% and critical temperature, T, of 38.1-38.6 K. This result and XRD data suggest that Sb does not enter the lattice of MgB. Impurity phases are MgSb, MgO, and MgB. The optimum addition is SbO for x = 0.005. This sample shows the critical current density, J(5 K, 0 T) = 4 × 10 A/cm and J(5 K, 7 T) = 6 × 10 A/cm, while the irreversibility field, H (5 K, 100 A/cm) = 8.23 T. Indicated values of J and H are higher than for the pristine sample. The mechanism of J and H increase in the SbO added samples is complex and composed of opposite effects most probably involving morphology elements, the presence of nano metric MgB and the indirect influence of oxygen or oxygen and Sb. Crystallite size of MgB is decreasing when Sb-based additions are introduced and the effect is stronger for the Sb-metal addition. The sample with Sb-metal addition does not improve J and H when compared with pristine sample. [ABSTRACT FROM AUTHOR]