Enhancement of flux pinning and Anderson–Dew-Hughes pinning analysis in Bi1.6Pb0.5Sr2−x TbxCa1.1Cu2.1O8+δ superconductor

Abstract The effect of substitution of rare-earth (RE), Tb on the critical current density ( J C ), pinning potential ( U 0 ) and flux pinning properties of (Bi,Pb)-2212 superconductor was studied. The XRD and EDS analyses show that Tb-atoms are successfully substituted into the (Bi,Pb)-2212 system. The critical temperature ( T C ), self-and in-field J C of Tb-substituted samples are found to be highly enhanced for optimum doping levels. The sample with x = 0.075 shows the maximum flux pinning force ( F P ) of 275 × 10 4 N m −3 and the peak position of F P shifts to higher fields (0.84 T) as against 3.0 × 10 4 N m −3 and 0.12 T for the pure-sample. In addition, the values of self-field J C and U 0 , calculated using Anderson's function are maximum for this sample ( x = 0.075). The Dew-Hughes pinning analysis shows that the main pinning mechanism is due to the point-defects brought about by the substitution of Tb-atoms at the Sr-site. The enhancements in J C ( B ) characteristics, values of U 0 , irreversibility field ( B irr ) and F P are of great scientific and technological significance and are explained on the basis of hole optimization and formation of point-defects due to the substitution of Tb at Sr-site of (Bi,Pb)-2212 system.