Lead substitutions for promoted critical current density Jc and mechanical properties of Mg1-xPbxB2 regime

Lead was used as softener dopant element to replace on magnesium sites in Mg1-xPbxB2 regime (where x = 0.0, 0.05, 0.1 and 0.2 mole). Samples were prepared via high temperature solid-state reaction technique depending upon diffusion mechanism of Mg/ Pb-vapour ions through boron-matrix. The maximum solubility limit of lead n was found to be similar to 0.2 mole, which emphasises that substitution on MgB2 system is stilling too limited and needs many precautions to be successful. The crystalline lattice constants were evaluated and exhibit noticeable length elongation in case of c-axis as x increases while a, b-axes were nearly constant. Furthermore, effect of Pb-doping was investigated carefully on microstructure and superconducting properties of MgB2 system. SE-microscopic analysis indicated that lead ions diffuse regularly through surface and bulk in case of (x = 0.05 and 0.1 mole) and grain size was estimated and found in between 0.43 and 1.6 mu m. Critical current densities (J(c)'s values) recorded an reasonable increase as Pb-content increase (from x = 0 to 0.1 mole) while recorded a slight decrease for sample with maximum lead content (x = 0.2 mole). The mechanical tensile strength of the samples was clearly improved linearly as Pb-content increase recording maximum tensile 31.7 MPa for sample with x = 0.2 mole. (C) 2006 Elsevier Ltd. All rights reserved.