Pb substitution effect on the normal and superconductivity states transport of polycrystalline MgB2

A series of samples of Mg1-xPbxB2 were synthesized by the conventional solid state reaction method. Its temperature dependence of resistivity was studied from the zero resistivity temperature Tc up to 300 K. In order to more understand the main reason of the decreases of Tc, we analyse the resistivity versus temperature data in the normal state using Bloch-Grueneisen formula. The Debye temperature, θD, has been extracted from the fits. θD is seen to decrease with the lead substitution from 1280 K to 835 K. Using θD and Tc, the electron-phonon interaction parameter λ, has been given by McMillan equation. The values of λ increase from 0.70 to 0.84 respectively for x=0% and x=1% sample. The decrease in Tc is argued mainly by the decrease in the density of states at the Fermi level N(EF) with Pb concentration than the decrease in θD. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)