State of the art Ag50-Sb Se50-Te alloys: Their high zT values, microstructures and related phase equilibria

Turning waste heat into electricity using thermoelectric materials supports the crucial goals of the sustainable development. Two ternary chalcogenide compounds, the AgSbTe_2 and AgSbSe_2, are viewed as prospective candidates for mid-temperature waste heat recovery (600–800 K). Alloying between the cubic AgSbTe_2 and AgSbSe_2 yields to the very high zT peak value of 1.4 in Ag_(25)Sb_(25)Se_(10)Te_(40) and Ag_(25)Sb_(25)Se_5Te_(45) at 680 K, which are nearly 40% and 250% higher than those of undoped AgSbTe_2 (zT ∼ 1) and AgSbSe_2 (zT ∼ 0.4). The relations between the phase stability, the carrier concentration and the electronic/thermal transport property are understood by conducting comprehensive study along the pseudo-binary AgSbSe_2–AgSbTe_2 system with varying values of x and y in Ag_(50-x)Sb_xSe_(50-y)Te_y (25 ⩽ x ⩽ 30, y ⩽ 50).