Thermoelectric Properties of Single-Crystal CeRhSn with Valence Fluctuations

概要

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The thermoelectric power $S$, electrical resistivity $\rho$ and thermal conductivity $\kappa$ have been measured for single crystals of CeRhSn and LaRhSn with the hexagonal ZrNiAl-type structure. For CeRhSn, a broad maximum of 60 μV/K appears in $S(T)$ along both the $a$- and $c$-axes at 160 K, being typical of a valence-fluctuating Ce compound. The $\rho_{a}(T)$ exhibits a high maximum of 350 μ$\Omega$cm at 70 K, whereas $\rho_{c}(T)$ decreases monotonically on cooling from 300 to 1.3 K. Although the measured $\kappa(T)$ for CeRhSn is smaller than that for LaRhSn, the phonon contribution $\kappa_{\text{ph}}$ for the former is approximately twofold that for the latter. The relation $\kappa_{\text{ph}}$(LaRhSn) $<$ $\kappa_{\text{ph}}$(CeRhSn) $<$ $\kappa_{\text{ph}}$(LaRhIn) suggests that the phonon scattering induced by atomic disorder is most significant in LaRhSn. The thermoelectric figure of merit $Z$ for CeRhSn has the maxima of $3\times 10^{-4}$ K-1 at 160 K and $7\times 10^{-4}$ K-1 at 130 K along the $a$- and $c$-axes, respectively.
2003-10-15