Thermoelectric properties of Hf1−xZrxTe5 polycrystals with high density

Hf_1-xZr_xTe₅, which is expected to have high thermoelectric performance at low temperature, is investigated on polycrystals with high density. in order to examine the possibility of large enhancement of the figure of merit at low temperature, polycrystalline samples of Hf_1-xZr_xTe₅ (x=0.0, 0.5 and 1.0) are systhesized by hot-press sintering to make high density above ~90%. Resultant polycrystals show anisotropy in the resistivity between parallel (//) and perpendicular (perp) sample is approximately twice smaller than that for // one and this behavior can come from the anisotropic resistivity in the single crystal of this system. Similar anisotropic behaviors are observed for all Hf_1-xZr_xTe₅ samples. The figure of merit of HfTe₅ increases largely by substituting Zr. ZT of ZrTe₅and Hf_0.5Zr_0.5Te₅ is ~0.1 at 300 K, which is 6 times larger than that of HfTe₅. The reduction iof the resistivity is responsible to this enhancement of ZT in both samples. In the present paper, thermoelectric properties of Hf_1-xZr_xTe₅ are discussed from the viewpoint of the sample preparation condition and the anisotropy in this system.