Superconductivity and Phase Transition of Zirconium under High Pressure up to 50 GPa

The superconducting transition temperature, T c , of group-IV transition metal zirconium has been studied as a function of pressure up to 50 GPa in relation to the pressure-induced structural phase transition. Corresponding to a phase transition from hexagonal to bcc structure, a discontinuous increase of the T c is observed at 30 GPa. For the bcc phase, a high T c of 11 K has been developed. The result suggests that an electronic configuration similar to that of the bcc Nb is induced in the bcc phase as a result of an increase in valence d -electron numbers by the s - d electronic transformation. The observation of the high T c is decisive experimental evidence for a pressure-induced transformation from group-IV transition metal to group-V transition metal.