Thermoelectric properties of Hf1−xZrxTe5 polycrystals with high density

Hf
_1-x
Zr
_x
Te
₅
, 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-x
Zr
_x
Te
₅
(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-x
Zr
_x
Te
₅
samples. The figure of merit of HfTe
₅
increases largely by substituting Zr. ZT of ZrTe
₅
and Hf
_0.5
Zr
_0.5
Te
₅
is ~0.1 at 300 K, which is 6 times larger than that of HfTe
₅
. The reduction iof the resistivity is responsible to this enhancement of ZT in both samples. In the present paper, thermoelectric properties of Hf
_1-x
Zr
_x
Te
₅
are discussed from the viewpoint of the sample preparation condition and the anisotropy in this system.