THERMAL-CONDUCTIVITY OF A BSCCO(2223) C-ORIENTED TAPE - A DISCUSSION ON THE ORIGIN OF THE PEAK

Thermal conductivity and electrical resistivity measurements have been performed on a highly c-oriented (BiPb)(2)Sr2Ca2Cu2O10 tape in the ra nge from 20 to 220 K. We analyse the experimental data in order to inv estigate the origin of the thermal conductivity maximum below T-c. Thr ee different cases are considered: (1) the electron contribution to th e thermal conductivity K-e, decreases as described by the Bardeen-Rick ayzen-Tewordt model, while the phonon contribution. K-ph, is responsib le for the peak (phonon approach); (2) K-e, described by means of the Kadanoff-Martin formalism, shows a peak while K-ph is a smooth decreas ing function of decreasing temperature (electron approach); (3) both c ontributions present a peak (phonon + electron approach). The models w e use involve some fundamental parameters, such as the amplitude of th e energy gap, the Debye temperature, the mean dimension of the grains and the residual electron-impurity scattering rate. The best fit is ob tained by the phonon + electron approach, but the phonon approach yiel ds a more correct value for the energy gap. Finally, within the employ ed framework, we can exclude that only the electron peak by itself mig ht account for our experimental data.