Research Areas

High valley degeneracy is just one of the peculiar features of PbTe based materials that makes them the most efficient thermoelectric materials for waste heat recovery. Alloying can finely tune the band structure to enhance thermoelectric performance as well as control doping and reduce thermal conductivity.

• Press Coverage: ScienceMag - PhysicsWorld - AmericanScientist - ArsTechnica
• “Lead Telluride Alloy Thermoelectrics” MaterialsToday 14, 526 (2011)
• "Convergence of electronic bands for high performance bulk thermoelectrics" Nature 473, 66 (2011)
• "High thermoelectric figure of merit in heavy hole dominated PbTe" Energy and Environmental Science vol, in press (2011)
• "Heavily doped p-type PbSe with high thermoelectric performance: an alternative of PbTe" Advanced Materials vol, in press (2011)
• "Reevaluation of PbTe1-xIx as high performance n-type thermoelectric material" Energy and Environmental Science vol, in press (2011)
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The rich solid-state chemistry of Zintl phases enables a directed search and optimization of new complex thermoelectric materials. The complex crystal structures of Zintl Phases lead to low phonon velocity and therefore low thermal conductivity while the chemistry of Zintl phases facilitates strategies for tuning the electronic transport.

• "Complex Thermoelectric Materials" Nature Materials 7, 105-114 (2008)
• "Zintl Chemistry for Designing High Efficiency Thermoelectric Materials" Chemistry of Materials, 22, p624 (2010)
• "Ca₃AlSb₃: an inexpensive, non-toxic thermoelectric material for waste heat recovery" Energy and Environmental Science 4, 510 (2011)
• "Electronic structure and transport in thermoelectric compounds AZn2Sb2 (A = Sr, Ca, Yb, Eu)" Dalton Trans. 39, p1046 (2010)
• "Characterization and analysis of thermoelectric transport in n-type BaGaGe" Physical Review B 80, 125205 (2009)
• "Composition and the thermoelectric performance of Zn4Sb3" Journal of Materials Chemistry (2010)
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Some thermoelectric materials contain fast-diffusing, even 'super-ionic' atoms within a crystalline sublattice of another type of atom. This extraordinary 'liquid-like' behaviour results in an intrinsically low lattice thermal conductivity which enables high zT in an otherwise simple semiconductor.

• “Liquid-like Copper Ion Thermoelectric Materials” Nature Materials, online (2012)
• "Disordered Zinc in Zn4Sb3 with Phonon Glass, Electron Crystal Thermoelectric Properties" Nature Materials, Vol 3, p 458-463 (2004)
  more Cu2Se... , more Zn4Sb3...

Thermoelectric Nanomaterials

Interfaces at the nanometer scale can be used to scatter long mean-free-path phonons to reduce the phonon or lattice thermal conductivity and increase zT.

• "Interfaces in Bulk Thermoelectric Materials" Current Opinion in Colloid & Interface Science 14, 226 (2009)
• "High Thermoelectric Performance in PbTe due to Large Nanoscale Ag2Te Precipitates and La Doping" Advanced Functional Materials (2010)
• "Formation of Sb2Te3 Widmanstätten precipitates in thermoelectric PbTe" Acta Materialia 57 p. 666 (2009)
• "Self-Assembled Nanometer Lamellae of Thermoelectric PbTe and Sb2Te3 with Epitaxy-like Interfaces" Chemistry of Materials 19(4) pp 763 - 767 (2007)
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