Fabrication and thermoelectric properties of Pb (Zn0.85Al0.15) Te-Te (y = 0, 0.04, 0.06, 0.08, and 0.11) nanocomposites

A series of Pb1-y(Zn0.85Al0.15)yTe-Te nanocomposites (y = 0, 0.04, 0.06, 0.08, and 0.11) was fabricated by hydrothermal synthesis of PbTe and Zn0.85Al0.15Te nanoparticles separately, followed by intimate mixing, pressing, and sintering in evacuated-and-encapsulated Pyrex ampoules at 380 °C for 12 h. Thermoelectric properties were characterized from 120-600 K. With increasing Zn content, the peak thermopower shifts to higher temperatures, Hall carrier concentration increases, and the lattice thermal conductivity decreases. As compared to the pristine PbTe, thermoelectric properties of Pb1-y(Zn0.85Al0.15)yTe-Te nanocomposites have improved considerably. The y = 0.11 sample exhibits the highest zT ~1 comparable to the state-of-the-art p-type PbTe-based materials. The enhanced zT is ascribed to reduced thermal conductivity, elevated electrical conductivity and thermopower. This unique new method of material synthesis and doping is very promising to obtain high-performance thermoelectric materials in addition to tuning their nanostructures.