A REVIEW OF HIGH TEMPERATURE SUPERCONDUCTING PROPERTY OF PDH SYSTEM

The discovery of superconductivity in palladium-hydrogen ( PdH ) and its isotopes ( D , T ) at low temperature, brought about extensive study of this system. These studies have shown that the critical transition temperature is a function of the H concentration x in the PdH x system with T c =9 K for x =1. In the last decade we defined a room temperature and room pressure technique to load H and maintain stable the stoichiometry in Pd lattice at levels higher than unit. Several magnetic and electric transport measurements have been performed showing transition temperature in the range of [18 K < T c < 273 K ]. Moreover in a typical critical current measurement configuration, current density greater than 6*10 4 Acm -2 ⊐ has been measured at liquid nitrogen temperature. The 263.5K superconducting transition after a week of sample storage at room pressure and temperature, decreased down to 261.5K and after 2 years it became 160.5K, demonstrating a fairly good stability of the sample. Evidences of the flux exclusion (ZFC measurements) and the flux expulsion (FC measurements) have been found at very high transition temperature ( Tc =235 K ) for the PdH system.