THERMOPOWER OF HIGH-T(C) MATERIALS AND ELECTRON-PHONON-IMPURITY INTERFERENCE

We show that the thermopower of alloys with nonisovalent substitution is described by renormalization due to electron-phonon-impurity interf erence. The thermopower of high-T(c) oxides as well as ordinary metall ic alloys is analyzed. For Bi- and Tl-based oxides the observed temper ature dependence with a maximum at 100-150 K and subsequent decrease w ith a sip change results from hole scattering on excess O2- ions. The more complicated situation in Y-Ba-Cu-O is also discussed to explain t he strong concentration dependence and different signs of the thermopo wer along the a and b axes. The electron-phonon coupling constant eval uated from experimental data has a reasonable value: 1-2.5.