Effect of a hot-press method on the critical current density of MgB 2 bulk samples

Abstract

A hot-press method was used for MgB 2 bulk samples, and the densification samples were prepared by the varying applied pressure. The critical current density J c of the sample was measured and the pressure and temperature dependences of J c were systematically investigated. The density of the bulk samples have improved by applying pressure in the direction of thickness of the sample while heating, and the density increased with the rise in the hot press pressure. In the sample processed at 400 kg/cm 2 and 730 °C, J c was around 9.7 × 10 5 A/cm 2 at 20 K, 2 T, which is at least three times the value of sample without hot pressing. The results suggest that densification of the sample by hot pressing contributes to the J c improvement in the MgB 2 bulk.