Suppression of flux-creep in (Bi,Pb)-2212 superconductor by holmium doping

The effect of substitution of rare-earth holmium on microstructure, and electrical and magnetic properties of (Bi,Pb)-2212 superconductor has been investigated. XRD and EDAX analyses show that Ho atoms are successfully substituted into the (Bi,Pb)-2212 system and they induce significant changes in the microstructure, hole concentration, critical temperature, self- and in-field critical current density (JC) of the system. Flux pinning force (FP) calculated from the field dependent JC values shows that the irreversibility lines of Ho-doped (Bi,Pb)-2212 shift towards higher fields to different extents depending on the Ho stoichiometry. Also the sample with (holmium content) x=0.075 shows the maximum FP of 172.5±1×104 N m−3 and the peak position of FP shifts to higher fields (0.76 T) as against 2.9±1×104 N m−3 and 0.12 T at 64 K for the pure sample. Enhancements in the in-field JC, irreversibility field and FP due to holmium doping are of great scientific and technological significance.