Bulk samples were formed by hot isostatic pressing of commercial powder at 100MPa and 950C. The resultant material was 100% dense, with a sharp superconducting transition at 37.5K. Microstructural studies have indicated the presence of small amounts of second phases within the material, namely MgO- and B-rich compositions, probably MgB4. Magnetization measurements performed at 20K revealed values of JC = 1.3 x 106A/cm2 at zero-field and 9.3 x 105A/cm2 at 1T. Magneto-optical studies revealed direct evidence for the superconducting homogeneity and strong intergranular current flow in the material.

Microstructure and Superconducting Properties of Hot Isostatically Pressed MgB2. T.C.Shields, K.Kawano, D.Holdom, J.S.Abell: Superconductor Science and Technology, 2002, 15, 202-5