Rapid fabrication and thermoelectric properties of Sn1.03Te-based materials with porous configuration

In this work, porous Sn1.03Te-based samples with and without 1 vol% K2Ti6O13 whiskers were prepared by applying a one-step spark plasma sintering (SPS) process combined with a piecewise pressurization method. The underlying reaction of Sn and Te elements during the one-step SPS process was revealed. The manifestation of hierarchical structures, including nano-micro-pore configurations, nanoparticle assemblies, and nano-whiskers, was demonstrated during this process. These all-scale structures can scatter phonons collectively over a wide range of frequencies. In addition, a remarkable decline in lattice thermal conductivity of 34.1% was achieved for the Sn1.03Te sample containing 1 vol% K2Ti6O13 whiskers compared to the pristine Sn1.03Te sample at room temperature, which was prepared by melting quenching and SPS. A lower lattice thermal conductivity for Sn1.03Te-1 vol% K2Ti6O13 sample was obtained over a wide temperature range. The significantly decreased lattice thermal conductivity leads to a maximum figure of merit ZT value of 0.7 at 873 K. This approach for the rapid fabrication of porous structures can also be employed to develop various types of thermoelectric materials.