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Materials for Thermoelectric Applications

Materials for Thermoelectric Applications

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Materials for Thermoelectric Applications

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  1. Materials for Thermoelectric Applications Jorge O. Sofo Department of Physics, Department of Materials Science and Engineering, and Materials Research Institute Penn State

  2. Thermoelectricians at work

  3. Thermoelectricians at work

  4. k-q q k Conductivity 101 Drude et al.

  5. Conductivity 101 ky kx

  6. Transport distribution

  7. “The best thermoelectric,” G. D. Mahan and J. O. Sofo Proc. Nat. Acad. Sci. USA, 93, 7436 (1996)

  8. The “Best” Thermoelectric

  9. Exciting Conductivity • First Born Approximation • Acoustic phonons • Optical phonons (polar, non-polar) • Ionized impurities • Inter-valley scattering • … C. Ambrosch-Draxl and J. O. SofoLinear optical properties of solids within the full-potential linearized augmented planewave methodComp. Phys. Commun. 175, 1-14 (2006)

  10. Careful… • Doping: rigid band • Gap problem • Temperature dependence of the electronic structure. • Alloys. Single site approximations do not work. • Many k-points

  11. T. J. Scheidemantel, C. Ambrosch-Draxl, T. Thonhauser, J. V. Badding, and J. O. Sofo. “Transport Coefficients from First-principles Calculations.” Phys. Rev. B68, 125210 (2003) Bi2Te3

  12. Bismuth

  13. Why is Bi so good?

  14. Bi vs. Bi2Te3 Improved thermoelectric devices using bismuth alloys T. Thonhauser, T. J. Scheidemantel, J. O. Sofo, Appl. Phys. Lett. 85, 588 (2004)

  15. Is there any hope?

  16. A Program by Georg Madsen and David Singh Courtesy of Georg Madsen

  17. Courtesy of Georg Madsen

  18. Georg Madsen’s

  19. Opals • Different scattering for phonons and electrons. • Work done for Allied Signal Corp. • Not an alternative… • 

  20. Summary • Tool to explore new compounds, pressure, “negative” pressure. • Prediction of a new compound by G. Madsen. • Easy to expand adding new Scattering Mechanisms • Limited to applications on “non-correlated” semiconductors. • The search for the best material continues…