Improved critical current properties observed in MgB₂ bulks synthesized by low-temperature solid-state reaction

MgB₂ bulks were synthesized by the solid-state reaction of Mg and B at 600 °C and their superconducting properties were compared with samples heated at 850 °C. The samples heated at 600 °C exhibited improved critical current properties up to high fields at 20 K. Poor crystallinity is found to contribute enhancement of H_c2, H_irr and J_c at high fields. On the other hand, the strongly grain connected network structure and smaller grain size are responsible for high J_c at low fields. Improved J_c up to 3.93 × 10⁵ A cm⁻² and a high μ₀H_irr of  T, as for undoped MgB₂ bulks, guarantees that low-temperature sintering is a promising way to fabricate MgB₂ conductors with high critical current performance.