Effect of 3d element substitution for Cu on the ac and dc magnetic properties of bulk (Bi, Pb):2223 superconductor

Abstract

The effect of the partial substitution of Cu by x = 0.02 Fe and x = 0.02 Ni in the (Bi, Pb):2223 superconductor was investigated by ac and dc susceptibility measurements. The linear dependence of intergranular temperature Tp on ac field amplitude agrees with the Müller critical state model. The intergrain pinning force density J varies influenced by the nature of 3d ions. Measurements of static susceptibility as a function of temperature in Fe and Ni x = 0.02 samples were analysed using a Curie-Weiss law with a temperature independent background. The effective magnetic moment obtained corresponds to a high spin state for both Fe3+ and Ni3+ ions, which substituted for Cu in the (Bi, Pb):2223 superconductor.