MAGNETIC-FIELD PENETRATION AND H-T PHASE-DIAGRAM OF Y-BA-CU-O SOL-GELSUPERCONDUCTORS BY SUSCEPTIBILITY AND MICROWAVE-ABSORPTION DATA

The a.c.susceptibility and microwave absorption as a function of appli ed magnetic field and of temperature were carried out for the sol-gel Y-Ba-Cu-O type high- temperature superconductors. The mixed states ass ociated with the intergrain weak superconducting links and the intragr ain regions were examined yielding the characteristic lines separating reversible and irreversible regions as well as the temperature depend encies of the lower critical fields inside the field- temperature H-T phase diagram. The data were analyzed in the frame of the giant flux c reep and the vortex glassy state models.