Thermoelectric properties of n- and p- type Ag2Te*

The recent discovery of phonon-liquid electron-crystal (PLEC) concept has led to an intensive research in some superionic compounds as potential thermoelectrics. In their high-temperature superionic phase they show liquid-like behavior as the anions move within the lattice. Here we focus on Ag₂Te which becomes superionic above a temperature of about T_SI =425K[1]. The puzzling behavior of it's physical and thermoelectric properties was repoted previously[2,3] for unknown reasons.
Here we discuss the sample dependence of the sign of thermopower (S) above and below the super-ionic transition and the large variation in it's electric conductivity value near room temperature (RT).On the other hand, the thermopower near RT was found to not to vary so dramatically, which in turn suggests the role of factors other than the carrier concentration may play in optimizing the thermoelectric properties of Ag₂Te. Very low-thermal conductivity (< 1 Wm^-1K^-1) observed, which can be attributed to the presence of a layered texture.For our n- type Ag₂Te, we found best zT_max value of 0.88 at 410 K.

1.Materials Transactions, Vol. 53, No. 7 (2012) pp. 1216 to 1219.
2.CrystEngComm, 2019, 21,1718.
3.Nano Lett. 2014, 14, 5398−5404.