Effects of high-pressure high-temperature sintering on the microstructures of Pb0.55Te0.45

The n-type nonstoichiometric Pb_0.55Te_0.45 materials were prepared by melting and quenching combined with a subsequent high pressure high temperature (HPHT) sintering. After adequately annealed at 623 K in the argon atmosphere, the microstructures and thermal transferring performance of the prepared samples have been systematically investigated. The results show that the grains of samples were apparently refined, as well as a large quantity of twisty layered structure and numerous particles with a size of ~200nm distributing in the grain boundary can be observed. These refined microstructures significantly block the transports of phonons, and result in a remarkable reduction of the lattice thermal conductivity compared with the corresponding melting ingots.