Reduced lattice thermal conductivity in nanograined Na-doped PbTe alloys by ball milling and semisolid powder processing

摘要

Achieving grains of less than 100 nm in bulk PbTe-based alloys is challenging, and yet can improve the thermoelectric performance of the alloys by reducing lattice thermal conductivity k_(lat), In this study, nanostructured Na_(0.02)Pb_(0.98)Te samples with grain sizes of 20-100 nm were fabricated by high energy ball milling and semisolid powder processing. Microstrucrures were investigated by scanning and transmission electron microscopies. The k_(lat) values of the samples showed significant reductions compared with those of reference samples with grains larger than 100 nm, mainly due to stronger phonon scattering at grain boundaries. The k_(lat) reached a minimum value of 0.74 W m~(-1) K~(-1) at 623 K.