We have carried out extensive characterization and measurements on a high purity Y IBa2Cu408+d ( 124) sample. Metallographic investigations, X-ray diffraction and microprobe analysis have been performed and reveal a single phase with traces of CuO. Resistivity measurements give a resistivity ratio R (300 K) /R( 100 K) of -_ 6.1, and a critical temperature r,, of 82.5 K. The AC susceptibility shows a sharp transition at about the same temperature.
The Meissner effect, with a 55% fraction (at 4.2 K with H= 20.3 Oe) confirms the bulk nature of the superconductivity.
The specific heat difference C( 0, T) -C( H, T) has been estimated from magnetization measurements in the vicinity of r, for&f= 8 T and compared to the direct calorimetric measurement. Both methods indicate that the specific heat jump amounts to approximately I5 mJ/K'mol. Fluctuation contributions are found up to several degrees above T,.
Inter-and intra-grain critical currents were determined at 4.2 K by AC inductive measurements and by measuring the irreversibility of the magnetization curve at a constant temperature (Bean's method). The results shows that there is no significant difference between the critical currents of the 124 phase and those of the 123 phase (Y ,Ba#Lt,O,).