Variation of MgB₂ growth mode and enhancement of critical current density by instantaneously 800 °C-triggered low-temperature sintering

Instantaneous high temperature improved the low-temperature sintering efficiency of the un-doped MgB₂ superconductor, and the MgB₂ was rapidly synthesized at 600 °C for only 2 h. In addition to the refinement of MgO impurity particles, the sudden high temperature induced defects within the MgB₂ grains, e.g. twinning crystal, and the J_c performance is therefore significantly enhanced, about 2.2 × 10³ A·cm^− 2 at 4 T for bulk sample. Differed from the two-dimensional nucleation growth mode of the MgB₂ grains in the high-temperature sintered un-doped sample, the low-temperature sintered MgB₂ grains accord with the dislocation growth mechanism, relying on the thermal-stress-triggered twinning crystal.