Lattice Dislocations Enhancing Thermoelectric PbTe in Addition to Band Convergence.
basic_science · Level V
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- Record sourced from PubMed, PMID 28397364.
- Also identified by DOI 10.1002/adma.201606768.
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Abstract
Phonon scattering by nanostructures and point defects has become the primary strategy for minimizing the lattice thermal conductivity (κ<sub>L</sub> ) in thermoelectric materials. However, these scatterers are only effective at the extremes of the phonon spectrum. Recently, it has been demonstrated that dislocations are effective at scattering the remaining mid-frequency phonons as well. In this work, by varying the concentration of Na in Pb<sub>0.97</sub> Eu<sub>0.03</sub> Te, it has been determined that the dominant microstructural features are point defects, lattice dislocations, and nanostructure interfaces. This study reveals that dense lattice dislocations (≈4 × 10<sup>12</sup> cm<sup>-2</sup> ) are particularly effective at reducing κ<sub>L</sub> . When the dislocation concentration is maximized, one of the lowest κ<sub>L</sub> values reported for PbTe is achieved. Furthermore, due to the band convergence of the alloyed 3% mol. EuTe the electronic performance is enhanced, and a high thermoelectric figure of merit, zT, of ≈2.2 is achieved. This work not only demonstrates the effectiveness of dense lattice dislocations as a means of lowering κ<sub>L</sub> , but also the importance of engineering both thermal and electronic transport simultaneously when designing high-performance thermoelectrics.