Thermoelectric properties of Ce-based Kondo semimetals and semiconductors

We report a systematic study of thermoelectric properties of a series of Ce-based compounds with the ε-TiNiSi-type structure; metallic CePtSn, semimetallic CeNiSn and CeRhSb, and semiconducting CeRhAs. In this sequence, both the Kondo temperature and hybridization-gap width increase, whereas the phonon thermal conductivity at high temperatures decreases. Opening of the pseudogap in CeRhSb and CeRhAs enlarges the thermopower, and leads to the maxima of the thermoelectric figure of merit, 1.7×10 −3 /K at 12 K and 1.0×10 −3/K at 115 K, respectively.