The influence of substitution and doping on the thermoelectric properties of CePd3

Intermediate valent CePd₃ exhibits one of the highest Seebeck coefficients (up to 120 muV/K at a broad maximum around 150 K) among Ce based intermetallics. Such strongly enhanced S(T) values are referred to an intense Kondo interaction responsible for a characteristic temperature T_K of about 240 K. Substitutions of Pd in CePd₃ by Rh increase the Ce valence towards the non-magnetic 4+ state, while a substitution with Ag shifts the valence towards 3+. Doping interstitial lattice-sites with B also reduces the valency. We have synthesized samples with following compositions Ce(Pd_1-xRh_x)₃B_0.05 and Ce(Pd_0.94-xRh_xAg_0.06)₃ to examine the possibility to compensate the loss of thermopower due to Ag substitution or B doping by Rh substitution and whether ZT can be improved by a further increase of the phonon scattering part of the thermal conductivity. The electrical resistivity rho(T), thermal conductivity lambda(T) and S(T) were measured allowing to calculate ZT. A further investigation of the measured data in the scope of empirical and theoretical models is presented.