High-Performance Tellurium-Free Thermoelectrics: All-Scale Hierarchical Structuring of p-Type PbSe-MSe Systems (M = Ca, Sr, Ba)
Hogan, Timothy P.
Dravid, Vinayak P.
Kanatzidis, Mercouri G.
UMass Chan AffiliationsDepartment of Quantitative Health Sciences
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AbstractWe present a systematic study of the characterization and thermoelectric properties of nanostructured Na-doped PbSe embedded with 1-4% MSe (M = Ca, Sr, Ba) phases as endotaxial inclusions. The samples were powder-processed by the spark plasma sintering technique, which introduces mesoscale-structured grains. The hierarchical architectures on the atomic scale (Na and M solid solution), nanoscale (MSe nanoprecipitates), and mesoscale (grains) were confirmed by transmission electron microscopy. These structures produce a great reduction in the lattice thermal conductivity relative to pristine PbSe without appreciably affecting the power factor. The lattice thermal conductivity can be reduced by up to approximately 29% when the second phase is added. The highest ZT value achieved was approximately 1.3 at 923 K for both 2% SrSe-and 3% BaSe-containing samples, while the sample containing 4% CaSe showed a ZT value of approximately 1.2 at 923 K. The optimal samples have hole carrier concentration of 1-2 x 1020 cm-3. We attribute the high ZT values to the combination of broad-based phonon scattering on multiple length scales and favorable charge transport through coherent interfaces between the PbSe matrix and MSe.
SourceJ Am Chem Soc. 2013 Mar 22. Link to article on publisher's site
Permanent Link to this Itemhttp://hdl.handle.net/20.500.14038/46611
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