Thermoelectric Properties of Layered Pd Oxide R2PdO4 (R = La, Nd, Sm, and Gd)

We prepared polycrystalline samples of R 2 PdO 4 (R = La, Nd, Sm, and Gd) using a NaCl flux technique. The measured resistivity is of the order of 10 3 –10 4 Ω cm at room temperature, which is two orders of magnitude smaller than those reported so far. We also studied the substitution effects of Ce for Nd in Nd 1.9 Ce 0.1 PdO 4 , where the substituted Ce decreases resistivity and the magnitude of thermopower. Activation energy gap of 70–80 meV and an effective mass of 15 evaluated from the measured data are suitable for thermoelectric materials, but a mobility of 10 -6 cm 2 /(V·s) is much lower than typical mobilities of 1–10 cm 2 /(V·s) for other thermoelectric oxides.