FLUCTUATION-INDUCED CONDUCTIVITY OF POLYCRYSTALLINE Y1-XCAXBA2CU3O7-DELTA SUPERCONDUCTORS

We report the fluctuation-induced conductivity of Ca doped Y1Ba2Ca3O7- delta samples. The analysis has been done with partial substitution of Ca(II) in place of Y(III). The Ca contents are 0.02, 0.05, 0.1 and 0. 2. In each case excess conductivity has been analysed and we tried to make a fit with the Aslamazov-Larkin and Lawrence-Doniach equations. I t is observed that our data fit well with the 3D AL equation and a cro ss-over from 2D to 3D has been found in our samples, For the first tim e we have employed this transition to estimate the Josephson coupling strength in the multiperiodic layered defect superconductor. This inte rlayer coupling strength J that controls the transition decreases with increase in Ca content, The variation of the Josephson coupling stren gth and T-c with x have been discussed. The Ginzburg-Landau coherence lengths xi(c)(0) for all cases have also been calculated and plotted.