Nanoporous PbSe–SiO₂ Thermoelectric Composites

Abstract

Nanoporous architecture has long been predicted theoretically for its proficiency in suppressing thermal conduction, but less concerned as a practical approach for better thermoelectric materials hitherto probably due to its technical challenges. This article demonstrates a study on nanoporous PbSe–SiO2 composites fabricated by a facile method of mechanical alloying assisted by subsequent wet‐milling and then spark plasma sintering. Owing to the formation of random nanopores and additional interface scattering, the lattice thermal conductivity is limited to a value as low as 0.56 W m−1 K−1 at above 600 K, almost the same low level achieved by introducing nanoscale precipitates. Besides, the room‐temperature electrical transport is found to be dominated by the grain‐boundary potential barrier scattering, whose effect fades away with increasing temperatures. Consequently, a maximum ZT of 1.15 at 823 K is achieved in the PbSe + 0.7 vol% SiO2 composition with >20% increase in average ZT, indicating the great potential of nanoporous structuring toward high thermoelectric conversion efficiency.

New synthesis route of highly porous InxCo4Sb12 with strongly reduced thermal conductivity

“…Reduction in hydrogen was also used as part of a CoSb 3 chemical alloying fabrication process by Khan et al [36] and chemical co-precipitation by Kim et al [37]; however, the porosities of the obtained materials were relatively low (\ 10%). Other thermoelectric materials with slightly higher porosity (* 14%) were recently reported [38,39], and in both cases, significant enhancement of the ZT parameter was observed due to the presence of pores.…”

High Thermoelectric Performance in PbSe–NaSbSe2 Alloys from Valence Band Convergence and Low Thermal Conductivity

“…Intriguingly, although the valence band structure of PbSe is more favorable than that of the conduction band for achieving high power factor ( S 2 σ), both p‐ and n‐type alloys have been reported to exhibit comparable maximum figures of merit near 1.6. Furthermore, the ZT s of the n‐type materials actually exceed those of the p‐type at most temperatures, yielding superior average ZT s of 1 over 300–900 K compared to values of only ≈0.5 for the p‐type compounds. This is the opposite of what is observed in PbTe systems.…”

Slowing down the heat in thermoelectrics

“…Porous structures are unique 3D body defects originating from the holes and bubbles incorporated into solid materials, which can also effectively reduce κ lat by scattering phonons and introducing thermal resistance on their surfaces 22,222,223 . In thermoelectric materials, nanoscale porous structures are often designed by modifying the synthesis process 222–225 . In the PbSe system, high‐density nanopores were introduced by adding extra SiO 2 nanoparticles via the ball‐milling method (Figure 12(A,B)) 224 .…”

“…In thermoelectric materials, nanoscale porous structures are often designed by modifying the synthesis process 222–225 . In the PbSe system, high‐density nanopores were introduced by adding extra SiO 2 nanoparticles via the ball‐milling method (Figure 12(A,B)) 224 . Randomly distributed nanopores with a large porosity of ~14% were obtained in PbSe‐0.9 vol% SiO 2 224 .…”