Using the transient thermoelectric effect (TTE), we have measured the thermoelectric power SðTÞ and the heat
conductivity kðTÞ of La1xSrxMnO3 ceramic surface layers with nominal compositions x ¼ 0:075; 0.1, 0.15, 0.2 and 0.3
in the temperature range 50–340 K. Except for a shift in the characteristic temperatures, the surface layer SðTÞ is still
similar to the bulk thermopower while the heat conductivity kðTÞ is markedly different, even changing the slope at
intermediate temperatures. As S is less structure sensitive than k; we relate these differences to an increased number
density of defects near the surface. In particular, a stoichiometry gradient close to the surface and oxygen vacancy
related (two level tunneling-) modes are indicated. In addition, new S and k data are presented for lower doping, i.e.
x ¼ 0:075 and 0.1. r 2001 Elsevier Science B.V. All rights reserved.