Influence of Mg particle size on the reactivity and superconducting properties of in situ MgB2

The effects of starting Mg particle size on the reactivity of Mg with B, and on remnant Mg in in situ MgB₂, and their influence on the superconducting system are studied. Samples were prepared by a powder-in-sealed tube (PIST) method, heat treated at 850 °C for 2 h in air and were characterized using XRD, SEM and magnetization measurements. As the particle size of Mg powder increases, residual Mg increases significantly. The MgB₂ prepared using smaller sized Mg powder does not have any residual Mg and show the best infield critical current density (J_C (H)).