Reproducible high thermoelectric figure of merit in Ag2Se

Ag2Se is a potentially useful material with interesting magnetoresistive and thermoelectric properties. In several recent studies, the thermoelectric figure of merit (zT) of Ag2Se has been shown to approach 1 near 380 K (i.e., about 25 K below its superionic transition temperature). However, what plagues the use of Ag2Se in real life applications is its sample dependence and very poor reproducibility. In a recent work, it is clearly established that the root cause of this is Ag migration during high-temperature sintering or melting. Here, we show that high-density Ag2Se samples with high and reproducible zT (0.92 at 370 K) can be prepared by simple all-room-temperature techniques. The ease of sample preparation and high zT along with excellent reproducibility make Ag2Se a promising material for near-room-temperature applications.