Improvement in the Performance of Bulk MgB2 Material through Optimization of Sintering Process

Enhancement of the critical current density (Jc) in MgB2 bulk material is very important for engineering applications. It has been found that the optimization of the sintering temperature leads to high Jc values in bulk MgB2 material. In our recent work, the highest trapped field value was recorded in the sample sintered at 775oC. The present investigation has focused on methods to improve further Jc values of the disk-shape bulk MgB2 superconductors by optimizing sintering conditions. MgB2 samples were subjected to a solid state reaction at 775, 780, 785, 795, 800 and 805oC for 3 h in pure Ar atmosphere. XRD analysis showed that all the samples were single phase MgB2. The magnetization measurements confirmed a sharp superconducting transition with onset Tc at around 38.7 K. Atomic force microscopy observation indicated that the number of nano meter size grains is more in samples processed 3 h at 805oC has compared to the samples sintered at 775oC. As a result, the highest Jc value of 245 kA/cm2 at 20 K was obtained for the sample sintered at 805oC for 3 h.