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Electrical power from heat: All-scale hierarchical thermoelectrics with and without earth-abundant materials.

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Electrical power from heat: All-scale hierarchical thermoelectrics with and without earth-abundant materials.

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Palestra plenária do XII Encontro da SBPMat (Campos do Jordão, setembro/outubro de 2013). Palestrante: Mercouri G Kanatzidis - Northwestern University e Argonne National Laboratory (EUA).

Palestra plenária do XII Encontro da SBPMat (Campos do Jordão, setembro/outubro de 2013). Palestrante: Mercouri G Kanatzidis - Northwestern University e Argonne National Laboratory (EUA).

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Electrical power from heat: All-scale hierarchical thermoelectrics with and without earth-abundant materials.

  1. 1. Electrical power from heat: Allscale hierarchical thermoelectrics with and without earth-abundant materials Mercouri Kanatzidis Northwestern University Sponsored by the Department of Energy
  2. 2. Rachel Korkosz Yeseul Lee Lidong Zhao Thomas Chasapis Kanishka Biswas
  3. 3. Collaborators                 Tim Hogan, MSU S. D. (Bhanu) Mahanti, MSU Ctirad Uher, Michigan Simon Billinge, Columbia Eldon Case, MSU Vinayak Dravid, NU Art Freeman, NU Jos Heremans, OSU Chris Wolverton, NU Ray Osborn, Argonne Stephane Rosenkranz, Argonne Ken Gray, Argonne David Seidman, NU John Mitchell, Argonne Duck Young Chung, Argonne Theodora Kyratsi, U Cyprus GROUP Vinayak Dravid, NU
  4. 4. Seebeck Effect Thermoelectricity - known in physics as the "Seebeck Effect" • In 1821, Thomas Seebeck, a German physicist, twisted two wires of different metals together and heated one end. • Discovered a small current flow and so demonstrated that heat could be converted to electricity. www.worldofenergy.com.au/07_timeline_w orld_1812_1827.html www.dkimages.com/discover/DKIMAGES/Discover/H ome/Science/Physics-and-Chemistry/Electricity-andMagnetism/General/General-18.html chem.ch.huji.ac.il/history/seebeck.html
  5. 5. Heat to Electrical Energy Directly Up to 20% conversion efficiency with right materials cold hot Thermopower S = ΔV/ΔT TE devices have no moving parts, no noise, reliable http://www.dts-generator.com/
  6. 6. Thermoelectric applications • Waste heat recovery • Automobiles • Over the road trucks • Marine • Utilities • Chemical plants • • • • Space power Remote Power Generation Solar energy Geothermal power generation • Direct nuclear to electrical
  7. 7. U.S. Energy Flow, 2009 http://www.eia.doe.gov/emeu/aer/ ~65% of energy becomes waste heat, ~10% conversion to useful forms can have huge impact on overall energy utilization
  8. 8. Figure of Merit and Conversion Efficiency electrical conductivity thermopower S ZT 0.6 900 K 700 K T total Total thermal conductivity 0.4 2 Power factor S 0.2 Tcold= 300K 0.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 ZT 14 2
  9. 9. What about thermal conductivity? • Diamond 1600 W/mK • Cu 400 W/mK • PbTe 2.2 W/mK • Wood 0.2 W/mK
  10. 10. Why finding a “good thermoelectric” (ZT > 1) is hard! Contra-indicated properties Power factor 1.2 Seebeck, S PF 0.9 conductivity, , electronic 0.6 ZT 0.3 0.0 18 19 20 log n 21 S 2 T “Power factor”
  11. 11. Leading thermoelectric materials • • • • • Bi2Te3-Sb2Te3 (ZT~1) (300K) PbTe: ZT~0.8 at 800 K (n-type) AgSbTe2-GeTe (TAGS): ZT~1.2, 700 K (p-type) Half-Heusler alloys (ZT~0.8, 900K) Skutterudites (M1, M2, M3)Fe4Sb12 (ZT~1.4, 900K, n-type) • Mg2(Si,Sn) (ZT~1, 1000 K) • Nanostructured PbTe, (ZT~2.2)
  12. 12. What kinds of materials make the best thermoelectrics? Isotropic structure T mx m y mz 3/ 2 Z max Anisotropic structure e r 1/ 2 For acoustic phonon scattering r=-1/2 latt m= effective mass =scattering time r= scattering parameter latt= lattice thermal conductivity T = temperature = band degeneracy Large comes with (a) high symmetry e.g. rhombohedral, cubic (b) off-center band extrema Complex electronic structure 19
  13. 13. Multiple valleys….are better 20
  14. 14. Best thermoelectric materials Developed new bulk thermoelectric materials with record ZTmax n-type: ZTmax ~1.6 at 700K p-type: ZTmax ~1.7 at 700K 2 Pb Ag 18 0.86 SbTe 20 LAST 1.5 0.95 0.30 Ni 0.05 Co 3.95 12 La Te 2 2 0.4 Mg Si Sn 2 0.6 0.4 3 0.5 4 1 800 1000 1200 Temperature (K) Bi Te 2 0.2 10 CeFe Sb 4 3 12 (AgSbTe ) 3 2 0.15 Ce 0.28 PbTe 0.5 (GeTe) 0.85 Fe Co Sb 1.5 2.5 12 Hsu et al, Science, 303, 818 (2004) Yb MnSb 14 400 600 11 800 1000 1200 Temperature (K) Major discovery: self-assembled nanodots in bulk materials responsible for record ZT’s 21 2 SiGe 0 600 6 Zn Sb PbTe 400 22 Ag Pb Sn Sb Te CoSb 3 0.5 0 0.6 20 3 ZT ZT Mg Si Sn p-type Materials p-type Pb SbTe 1.5 Sb 2 Bi Te Na PbTe-PbS(8%) Ba 1 2 n-type Materials n-type
  15. 15. Endotaxial nanostructures Endotaxy: Coherent lattice matched placement of one crystal inside another Key aspects: Interfaces Strain Band offsets Stability K. F. Hsu, etal Science 2004, 303, 818-821. P. F. P. Poudeu, etal Angew. Chem. Int. Ed. 2006, 45, 3835-3839. J. Androulakis, et al J. Am. Chem. Soc. 2007, 129 (31), 9780-9788. K. Biswas, etal Nature Chemistry 2011, 3, 160-166. K. Biswas, etal Nature, 2012, 419, 414-418. matrix
  16. 16. electronic band structure of PbTe Valence band is multiple a≈6.45 Å (300K) peaks m*Σ (~2m0) >> m*L(~0.2m0)
  17. 17. PbTe-x%SrTe Transmission Electron Microscopy
  18. 18. (c VB 200 +++ +++ 100 Valence bands of PbTe…. 0 300 400 500 600 PbTe 700 T (K) f 300 27 CB 24 200 2 150 100 21 18 15 6 300 400 500 600 700 800 900 T (K) ~0.30 eV Thermal excitation of holes to Σ band 12 9 50 E (eV) 250 S ( V/K) T = 500 K 2 .S ( W/cmK ) e PbTe SrTe VB L Σ 300 400 500 Heavy hole band Light hole band 600 700 800 900 T (K) Rising temperature
  19. 19. Through band alignment
  20. 20. Nano-scale, meso-scale Submicron grains nanostructures mesostructures
  21. 21. Thermal conductivity PbTe-x%SrTe 1.2 (W/mK) 3.2 2.8 lat 2.0 0.8 lat (W/mK) 2.4 Ingot 1.6 0.4 1.2 SPS 0.8 600 0.4 300 400 500 600 700 800 900 T (K) K. Biswas, Jiaqing He, I. D. Blum, C-I Wu, T. P. Hogan, D. N. Seidman, V. P. Dravid & M. G. Kanatzidis Nature 2012, 489, 414–418 700 800 T (K) 900
  22. 22. Thermal conductivity PbTe-x%SrTe (S/cm) 2000 4% SrTe, 2% Na: SPS 2% SrTe, 2% Na: SPS 0% SrTe, 2% Na: SPS 4% SrTe, 2% Na: Ingot 2% SrTe, 1% Na: Ingot[14] b 350 300 250 S ( V/K) a 2500 1500 1000 200 150 100 500 0 50 30 (W/mK) 20 10 0 300 400 500 600 700 800 900 T (K) d 4.4 total 2 2 S ( W/cmK ) c 0 300 400 500 600 700 800 900 T (K) 300 400 500 600 700 800 900 T (K) f 4.0 3.6 3.2 2.8 2.4 2.0 1.6 1.2 0.8 300 400 500 600 700 800 900 T (K)
  23. 23. All length scales: record high ZT Increasing efficiency 2.4 ZT ~ 1.1 2.0 ZT ~ 1.7 ZT ~ 2.2 Atomic scale 4% SrTe, 2% Na: SPS 2% SrTe, 1% Na: Ingot[14] 0% SrTe, 2% Na: Ingot Nano scale Meso scale ZT 1.6 1.2 All-scale hierarchical architecture 0.8 0.4 0.0 300 450 600 T, K 750 900 K. Biswas, Jiaqing He, I. D. Blum, C-I Wu, T. P. Hogan, D. N. Seidman, V. P. Dravid & M. G. Kanatzidis Nature 2012, 489, 414–418 1 cm
  24. 24. What is the proof that nanostructures reduce thermal conductivity?
  25. 25. Model PbTe – PbS system for nanostructured TEs Nucleation and Growth ºC 1100 (PbTe)0.92(PbS)0.08 1000 900 800 Solid Solution 700 Spinodal Decomposition 600 0 10 20 PbS Miscibility Gap 30 40 50 mol. % PbTe Nucleation & Growth 60 70 80 Chemical Spinodal 90 100 PbTe J. D. Gunton and M. Droz, Lecture Notes in Physics: Introduction to the Theory of Metastable and Unstable States, Vol. 183 (Springer-Verlag, Berlin, Heidelberg, New York, Tokyo, 1983) pp. 1-13. 35 Leute, V., Volkmer, N. Z. Phys. Chem. NF., 144 1985, 145
  26. 26. PbTe0.92S0.08 Significant reduction in κlat PbTe0.92S0.08 Solid solution Solid solution heat (PbTe)0.92(PbS)0.08 Nanostructured We can see the effect of nanoscale precipitation of PbS in situ on the lattice thermal conductivity. , W/mK lat 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 ~50% Reduction in κlat (PbTe)0.92(PbS)0.08 Run 1 Heating Run 1 Cooling Annealed Sample 300 400 500 600 700 Temperature, K S. Girard, Jiaqing He (PbTe)0.92(PbS)0.08 Nanostructured
  27. 27. Te free? PbS: the cheapest thermoelectric Nanostructuring PbS with second phases
  28. 28. PbS-Bi2S3 phase diagram Nucleation and growth Binary phase diagram of PbS-Bi2S3(Sb2S3) Garvin P. F., Neues Jahrb. Mineral., Abh., 118, 235(1973)
  29. 29. n-type PbS with second phases PbS with second phases without doping Second phases: Bi2S3, Sb2S3
  30. 30. n-type PbS with second phases -100 12 -2 -1 -200 -300 500 300 400 500 600 700 Temperature (K) -400 9 6 3 0 300 400 500 600 700 Temperature (K) Significantly reduce 300 400 500 600 700 Temperature (K) PbS with Sb2S3~ 0.78 @ 723 K 1.0 ~ 0.80 @ 723 K 0.8 0.6 ZT 0 15 PF ( Wcm K ) 1000 0 ) 1500 PbS PbS+1% PbCl2 PbS+1% Bi2S3+1% PbCl2 PbS+2% Bi2S3+1% PbCl2 PbS+3% Bi2S3+1% PbCl2 PbS+4% Bi2S3+1% PbCl2 PbS+5% Bi2S3+1% PbCl2 -1 2000 Seebeck independent on second phases S( VK 2500 PbS PbS+1% PbCl2 PbS+1% Sb2S3+1% PbCl2 PbS+2% Sb2S3+1% PbCl2 PbS+3% Sb2S3+1% PbCl2 PbS+4% Sb2S3+1% PbCl2 PbS+5% Sb2S3+1% PbCl2 0.4 0.2 0.0 300 400 500 600 700 Temperature (K)
  31. 31. TEM: nanostructured PbS PbS+1.0 at. % Bi2S3+1.0 at. % PbCl2 PbS + 1.0 at. % Sb2S3 + 1.0 at. % PbCl2
  32. 32. Nanostructures n-type PbS, ZT=1.1 ZT ~ 1.1 @ 923 K M: normal melting B: Bridgman Good repeatability ! S: SPS ZT ~ 1.06 @ 923 K BN coating
  33. 33. P-type Pb0.975Na0.025S-3%CaS/SrS Both total and lattice κ were reduced by SrS inclusions Pb0.975Na0.025S+3%SrS shows ZT about 1.2 at 923K, Pb0.975Na0.025S+3%CaS shows ZT about 1.1 at 923K, Zhao, L.-D. et. al., JACS. 133(2011)20476. & JACS. 134(2012)7902
  34. 34. TEM of Pb0.975Na0.025S -3%SrS Fine grain size, Sr containing precipitates, and no spot diffraction splitting for Pb0.975Na0.025S-3% SrS. crystallographic alignment between PbS and SrS, strain maps and lattice parameter difference at the interface between PbS and SrS.
  35. 35. GROUP Raising ZT of p-type PbS with endotaxial nanostructuring and valence-band offset engineering using CdS and ZnS
  36. 36. PbS is promising GROUP PbS is an ideal TE system because high performance in both n-type (ZT~1.1 at 923 K) and p-type (ZT~1.1 at 923 K) can be achieved. Zhao, L.-D. et. al., JACS. 133(2011)20476. & JACS. 134(2012)7902 n-type p-type Band gap energy levels of the metal sulfides, PbS, CdS, ZnS, CaS and SrS, all in the NaCl structure
  37. 37. µ (cm2/V-sec) mobility, μ at 920 K PbS CdS GROUP 40 cm2/V-sec ZnS CaS SrS 4% MS p-type, CdS containing sample shows higher μ
  38. 38. ZT for PbS system ~1.3 @923K (a) Eg PbS VB E’g minimal valence band offset ΔE CdS 0.13e V (b) e e PbS phonons CdS phonon-blocking/electron-transmitting Zhao L.D. et al. JACS, 2012 GROUP
  39. 39. GROUP
  40. 40. Panoscopic view of thermoelectrics Atoms/molecular motifs Angstrom and sub-nm scale Electronic Structure Crystal Structure Crystal lattice & point defects Classical Microstructure Sub-nm to Nano-scale Precipitates & nanoscale defects Thin films/multilayers Interfaces Residual stresses Hierarchical Length-scale Architecture: Implications for “Nanostructured” Thermoelectrics  Interactions along varied length-scales  Identification of individual microstructure elements in electronic and phonon transport Interfaces Micro-to macro-scale Macroscale Device Architecture Macro-, and device-scale Interfaces  Tailoring and design of “microstructure”
  41. 41. 2.2 2.2 PbTe-x%SrTe Panoscopic… NaPb20SbTe20 PbTe-PbS (nanostructured) PbTe-PbSe
  42. 42. Conclusions • A panoscopic view is required going forward • Band alignment engineering between nanostructures and matrix: ZT~2.2 at 900K • Superior properties in p-type PbTe-SrTe achieved through endotaxial placement of nanoprecipitates – Nanostructures do not reduce the power factor and function exclusively as phonon scatterers • Large power factor enhancements are needed for continued ZT increases • High performance in nanostructured PbS (ZT~1.2-1.3 at 900 K)

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