Enhanced thermoelectric performance and novel nanopores in AgSbTe2 prepared by melt spinning

We report a melt-spinning spark-plasma-sintering synthesis process of the polycrystalline p-type material composed of AgSbTe2 coarse grains and evenly formed 5–10 nm pores that occur primarily on the surface of matrix grains. The formation mechanism of nanopores and their influences on the thermoelectric properties have been studied and correlated. Microstructure analysis shows that the as-prepared sample can be regarded as a nanocomposite of matrix and in situ generated nanopores evenly coated on matrix grains. For the single-phase component and the possible energy-filter effect caused by the nanopores, the electrical transport properties are improved. Moreover, the thermal conductivity is significantly reduced by strong phonon scattering effect resulted from the nanopores. The thermoelectric performance of the as prepared sample enhances greatly and a ZT of 1.65 at 570 K is achieved, increasing∼200% compared with the sample prepared by traditional melt and slow-cooling method.