Enhanced superconducting properties of bulk MgB2 prepared by in situ Powder-In-Sealed-Tube method

A systematic study on the superconducting properties of polycrystalline MgB2 synthesized by in situ Powder-In-Sealed-Tube technique is carried out at different temperatures (750-900 °C). Both XRD and SEM results show well-crystallized MgB2 grains in all the samples and grain size is found to be increasing with the sintering temperature. Sharp superconducting transitions are observed for all samples, irrespective of sintering temperatures, which implies the high degree phase purity and homogeneity of MgB2 formed, while JC(H) plot gives sample dependent critical current density. The samples heat treated at relatively low temperatures show enhanced flux pinning and hence improved JC(H) performance. The reduced grain size and hence increased density of grain boundary pinning centers of MgB2 bulks synthesized at low temperature are mainly responsible for the enhanced flux pinning and JC.