  We investigated the thermoelectric transport properties of EuNi2P2 and
EuIr2Si2 in order to evaluate the relevance of Kondo interaction and valence
fluctuations in these materials. While the thermal conductivities behave
conventionally, the thermopower curves exhibit large values with pronounced
maxima as typically observed in Ce- and Yb-based heavy-fermion materials.
However, neither the positions of these maxima nor the absolute thermopower
values at low temperature are in line with the heavy-fermion scenario and the
moderately enhanced effective charge carrier masses. Instead, we may relate the
thermopower in our materials to the temperature-dependent Eu valence by taking
into account changes in the chemical potential. Our analysis confirms that
valence fluctuations play an important role in EuNi2P2 and EuIr2Si2.
