The effects of sintering temperature on superconductivity of MgB2 prepared by hot pressing

Abstract

The [Formula: see text] superconductor bulks were prepared by hot-pressing under the pressure of 55 MPa at different temperatures of 650[Formula: see text]C, 700[Formula: see text]C, 800[Formula: see text]C, 900[Formula: see text]C, 1000[Formula: see text]C, respectively, and the hot-pressing effects on the superconducting properties of [Formula: see text] bulks were investigated. The density of bulk samples increased with the rise of sintering temperature and the density reached to the maximum value when the sintering temperature rose to 1000[Formula: see text]C. For the sample sintered at 1000[Formula: see text]C, the critical transition temperature ([Formula: see text] reached the highest value of 38.8 K despite the high content of [Formula: see text] (30.62 wt.%). However, the critical current density ([Formula: see text] did not increase with the increase in the density and [Formula: see text]. The sample sintered at 700[Formula: see text]C maintained the high superconducting volume and had a small grain size, thus providing the best magnetic flux pinning force and [Formula: see text]. An effective hot-pressing process to improve [Formula: see text] might be the way to prepare by further increasing the density of sintering samples at 700[Formula: see text]C.