Superconducting Properties of MgB₂ Prepared by HighPressure and Ambient Pressure

The new superconductor MgB₂ has been prepared by two ways: high pressure and ambient pressure synthesis. Their superconducting properties were measured and compared. It is found that the sample prepared by high pressure is much denser than that prepared under ambient pressure. Accordingly the high pressure sample has a very narrow transition width and a much higher bulk critical current density.