LFMA and irreversibility line studies on Vanadium doped Bi(2223) superconducting system

Abstract

Suresh Babu et al [7] have reported the stabilization of Bi high T c (105 K) phase by vanadium oxide doped Bi(2223) superconducting system. Stabilization of Bi high T c phase in the absence of Pb makes this system interesting. In this paper we report low field microwave absorption (LFMA) studies of Bi 2−xV x Sr 2 Ca 2 Cu 3 O y (x=0 and 0.4 superconducting samples. Temperature dependent LFMA signal amplitude of x=0 sample showed definite peaks at 97 K and 70 K which may correspond to the 2223 and 2212 phases. In the case of x=0.4 sample, it showed a single peak at 90 K corresponding to 2223 phase. The thermodynamical critical magnetic field H Cl ∗ and average Josephson loop diameter was estimated for these samples from the LFMA signals. In addition we have also determined the irreversibility line from ZFC and FC susceptibility measurements. The irreversibility line followed the universal law H ∗= H o(1- T ∗/ T c) a . n and H o were foud to be 2.8 and 4075 Oe respectively.