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

PbTe was firstly fabricated by ball milling and semisolid powder processing (SPP).Grains less than 100 nm were achieved in PbTe alloys.The nanoscale grains reduced the lattice thermal conductivity of the SPP samples.The lattice thermal conductivity of SPP sample was lower than those of counterparts.

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 κlat. In this study, nanostructured Na0.02Pb0.98Te samples with grain sizes of 20–100 nm were fabricated by high energy ball milling and semisolid powder processing. Microstructures were investigated by scanning and transmission electron microscopies. The κlat 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 κlat reached a minimum value of 0.74 W m−1 K−1 at 623 K.