High-pressure in situ studies were performed, at up to 1.0GPa, of a superconductor which had been synthesized at high pressure. The as-prepared sample was of high quality as regard to its having a sharp TC at 39K. The in situ high-pressure measurements were carried out by using a Be–Cu piston–cylinder-type instrument with a mixed oil as the pressure-transmitting medium. This provided a quasi-hydrostatic pressure environment at low temperatures. The superconducting transitions were measured by using the electrical conductance method. It was found that TC increased with pressure in the initial pressure range, leading to a parabolic-like TC–P evolution.

The Increase in TC for MgB2 Superconductor under High Pressure. Z.X.Liu, C.Q.Jin, J.Y.You, S.C.Li, J.L.Zhu, R.C.Yu, F.Y.Li, S.K.Su: Journal of Physics - Condensed Matter, 2002, 14, 11301-4