Fine grained polycrystalline samples were synthesized from the elements to contain < 5% of impurity phases, according to X-ray powder diffractometry. The superconductive transition was sharp with a mid-point TC = 38.5K. The magnetization in the vortex state was studied as a function of applied field H, temperature T and time t. From the equilibrium magnetization, the London penetration depth was obtained. The supercurrent density J(T,H,t) in the vortex state (derived from the irreversible magnetization) decreased approximately linearly with T, in contrast to the quasi-exponential fall-off in high-TC superconductors. The current was highly stable in time, with normalized decay rates S = - dln[J]/dln[t] well below those in high-TC materials. These results were compared with those of other superconductors.

High Temporal Stability of Supercurrents in MgB2 Materials. J.R.Thompson, M.Paranthaman, D.K.Christen, K.D.Sorge, H.J.Kim, J.G.Ossandon: Superconductor Science and Technology, 2001, 14, L17-20